Longitudinal relationships among depressive symptoms, cortisol, and brain atrophy in the neocortex and the hippocampus.

OBJECTIVE: Depression is associated with accelerated aging and age-related diseases. However, mechanisms underlying this relationship remain unclear. The aim of this study was to longitudinally assess the link between depressive symptoms, brain atrophy, and cortisol levels. METHOD: Participants from the Betula prospective cohort study (mean age = 59 years, SD = 13.4 years) underwent clinical, neuropsychological and brain 3T MRI assessments at baseline and a 4-year follow-up. Cortisol levels were measured at baseline in four saliva samples. Cortical and hippocampal atrophy rates were estimated and compared between participants with and without depressive symptoms (n = 81) and correlated with cortisol levels (n = 49). RESULTS: Atrophy in the left superior frontal gyrus and right lingual gyrus developed in parallel with depressive symptoms, and in the left temporal pole, superior temporal cortex, and supramarginal cortex after the onset of depressive symptom. Depression-related atrophy was significantly associated with elevated cortisol levels. Elevated cortisol levels were also associated with widespread prefrontal, parietal, lateral, and medial temporal atrophy. CONCLUSION: Depressive symptoms and elevated cortisol levels are associated with atrophy of the prefrontal and limbic areas of the brain.

Medial temporal lobe atrophy ratings in a large 75-year-old population-based cohort: gender-corrected and education-corrected normative data.

OBJECTIVES: To find cut-off values for different medial temporal lobe atrophy (MTA) measures (right, left, average, and highest), accounting for gender and education, investigate the association with cognitive performance, and to compare with decline of cognitive function over 5 years in a large population-based cohort. METHODS: Three hundred and ninety 75-year-old individuals were examined with magnetic resonance imaging of the brain and cognitive testing. The Scheltens's scale was used to assess visually MTA scores (0-4) in all subjects. Cognitive tests were repeated in 278 of them after 5 years. Normal MTA cut-off values were calculated based on the 10th percentile. RESULTS: Most 75-year-old individuals had MTA score ≤2. Men had significantly higher MTA scores than women. Scores for left and average MTA were significantly higher in highly educated individuals. Abnormal MTA was associated with worse results in cognitive test and individuals with abnormal right MTA had faster cognitive decline. CONCLUSION: At age 75, gender and education are confounders for MTA grading. A score of ≥2 is abnormal for low-educated women and a score of ≥2.5 is abnormal for men and high-educated women. Subjects with abnormal right MTA, but normal MMSE scores had developed worse MMSE scores 5 years later. KEY POINTS: • Gender and education are confounders for MTA grading. • We suggest cut-off values for 75-year-olds, taking gender and education into account. • Males have higher MTA scores than women. • Higher MTA scores are associated with worse cognitive performance.

Plasma protein biomarkers of Alzheimer's disease endophenotypes in asymptomatic older twins: early cognitive decline and regional brain volumes.

There is great interest in blood-based markers of Alzheimer's disease (AD), especially in its pre-symptomatic stages. Therefore, we aimed to identify plasma proteins whose levels associate with potential markers of pre-symptomatic AD. We also aimed to characterise confounding by genetics and the effect of genetics on blood proteins in general. Panel-based proteomics was performed using SOMAscan on plasma samples from TwinsUK subjects who are asymptomatic for AD, measuring the level of 1129 proteins. Protein levels were compared with 10-year change in CANTAB-paired associates learning (PAL; n = 195), and regional brain volumes (n = 34). Replication of proteins associated with regional brain volumes was performed in 254 individuals from the AddNeuroMed cohort. Across all the proteins measured, genetic factors were found to explain ~26% of the variability in blood protein levels on average. The plasma level of the mitogen-activated protein kinase (MAPK) MAPKAPK5 protein was found to positively associate with the 10-year change in CANTAB-PAL in both the individual and twin difference context. The plasma level of protein MAP2K4 was found to suggestively associate negatively (Q < 0.1) with the volume of the left entorhinal cortex. Future studies will be needed to assess the specificity of MAPKAPK5 and MAP2K4 to eventual conversion to AD.

Practical cut-offs for visual rating scales of medial temporal, frontal and posterior atrophy in Alzheimer's disease and mild cognitive impairment.

BACKGROUND: Atrophy in the medial temporal lobe, frontal lobe and posterior cortex can be measured with visual rating scales such as the medial temporal atrophy (MTA), global cortical atrophy - frontal subscale (GCA-F) and posterior atrophy (PA) scales, respectively. However, practical cut-offs are urgently needed, especially now that different presentations of Alzheimer's disease (AD) are included in the revised diagnostic criteria. AIMS: The aim of this study was to generate a list of practical cut-offs for the MTA, GCA-F and PA scales, for both diagnosis of AD and determining prognosis in mild cognitive impairment (MCI), and to evaluate the influence of key demographic and clinical factors on these cut-offs. METHODS: AddNeuroMed and ADNI cohorts were combined giving a total of 1147 participants (322 patients with AD, 480 patients with MCI and 345 control subjects). The MTA, GCA-F and PA scales were applied and a broad range of cut-offs was evaluated. RESULTS: The MTA scale showed better diagnostic and predictive performances than the GCA-F and PA scales. Age, apolipoprotein E (ApoE) ε4 status and age at disease onset influenced all three scales. For the age ranges 45-64, 65-74, 75-84 and 85-94 years, the following cut-offs should be used. MTA: ≥1.5, ≥1.5, ≥2 and ≥2.5; GCA-F, ≥1, ≥1, ≥1 and ≥1; and PA, ≥1, ≥1, ≥1 and ≥1, respectively, with an adjustment for early-onset ApoE ε4 noncarrier AD patients (MTA: ≥2, ≥2, ≥3 and ≥3; and GCA-F: ≥1, ≥1, ≥2 and ≥2, respectively). CONCLUSIONS: If successfully validated in clinical settings, the list of practical cut-offs proposed here might be useful in clinical practice. Their use might also (i) promote research on atrophy subtypes, (ii) increase the understanding of different presentations of AD, (iii) improve diagnosis and prognosis and (iv) aid population selection and enrichment for clinical trials.

White matter changes in familial Alzheimer's disease.

BACKGROUND: Familial Alzheimer's disease (FAD) resulting from gene mutations in PSEN1, PSEN2 and APP is associated with changes in the brain. OBJECTIVE: The aim of this study was to investigate changes in grey matter (GM), white matter (WM) and the cerebrospinal fluid (CSF) in FAD. SUBJECTS: Ten mutation carriers (MCs) with three different mutations in PSEN1 and APP and 20 noncarriers (NCs) were included in the study. Three MCs were symptomatic and seven were presymptomatic (pre-MCs). METHODS: Whole-brain GM volume as well as fractional anisotropy (FA) and mean diffusivity (MD) using voxel-based morphometry and tract-based spatial statistics analyses, respectively, were compared between MCs and NCs. FA and MD maps were obtained from diffusion tensor imaging. RESULTS: A significant increase in MD was found in the left inferior longitudinal fasciculus, cingulum and bilateral superior longitudinal fasciculus in pre-MCs compared with NCs. After inclusion of the three symptomatic MCs in the analysis, the regions became wider. The mean MD of these regions showed significant negative correlation with the CSF level of Aß42, and positive correlations with P-tau181p and T-tau. No differences were observed in GM volume and FA between the groups. CONCLUSIONS: The results of this study suggest that FAD gene mutations affect WM diffusivity before changes in GM volume can be detected. The WM changes observed were related to changes in the CSF, with similar patterns previously observed in sporadic Alzheimer's disease.

The influence of negative life events on hippocampal and amygdala volumes in old age: a life-course perspective.

BACKGROUND: Psychosocial stress has been related to changes in the nervous system, with both adaptive and maladaptive consequences. The aim of this study was to examine the relationship of negative events experienced throughout the entire lifespan and hippocampal and amygdala volumes in older adults. METHOD: In 466 non-demented old adults (age range 60-96 years, 58% female), hippocampal and amygdala volumes were segmented using Freesurfer. Negative life events and the age at which these events occurred were assessed by means of a structured questionnaire. Using generalized linear models, hippocampal and amygdala volumes were estimated with life events as independent variables. The statistical analyses were adjusted for age, gender, intracranial volume, lifestyle factors, cardiovascular risk factors, depressive symptoms, and cognitive functioning. RESULTS: Total number of negative life events and of late-life events, but not of early-life, early-adulthood, or middle-adulthood events, was related to larger amygdala volume. There were interactions of early-life events with age and gender. Participants who reported two or more early-life events had significantly smaller amygdala and hippocampal volumes with increasing age. Furthermore, smaller hippocampal volume was found in men who reported two or more early-life events, but not in women. CONCLUSIONS: These results suggest that the effect of negative life events on the brain depends on the time when the events occurred, with the strongest effects observed during the critical time periods of early and late life.

Random Forest ensembles for detection and prediction of Alzheimer's disease with a good between-cohort robustness.

Computer-aided diagnosis of Alzheimer's disease (AD) is a rapidly developing field of neuroimaging with strong potential to be used in practice. In this context, assessment of models' robustness to noise and imaging protocol differences together with post-processing and tuning strategies are key tasks to be addressed in order to move towards successful clinical applications. In this study, we investigated the efficacy of Random Forest classifiers trained using different structural MRI measures, with and without neuroanatomical constraints in the detection and prediction of AD in terms of accuracy and between-cohort robustness. From The ADNI database, 185 AD, and 225 healthy controls (HC) were randomly split into training and testing datasets. 165 subjects with mild cognitive impairment (MCI) were distributed according to the month of conversion to dementia (4-year follow-up). Structural 1.5-T MRI-scans were processed using Freesurfer segmentation and cortical reconstruction. Using the resulting output, AD/HC classifiers were trained. Training included model tuning and performance assessment using out-of-bag estimation. Subsequently the classifiers were validated on the AD/HC test set and for the ability to predict MCI-to-AD conversion. Models' between-cohort robustness was additionally assessed using the AddNeuroMed dataset acquired with harmonized clinical and imaging protocols. In the ADNI set, the best AD/HC sensitivity/specificity (88.6%/92.0% - test set) was achieved by combining cortical thickness and volumetric measures. The Random Forest model resulted in significantly higher accuracy compared to the reference classifier (linear Support Vector Machine). The models trained using parcelled and high-dimensional (HD) input demonstrated equivalent performance, but the former was more effective in terms of computation/memory and time costs. The sensitivity/specificity for detecting MCI-to-AD conversion (but not AD/HC classification performance) was further improved from 79.5%/75%-83.3%/81.3% by a combination of morphometric measurements with ApoE-genotype and demographics (age, sex, education). When applied to the independent AddNeuroMed cohort, the best ADNI models produced equivalent performance without substantial accuracy drop, suggesting good robustness sufficient for future clinical implementation.

The association between biomarkers in cerebrospinal fluid and structural changes in the brain in patients with Alzheimer's disease.

BACKGROUND: Biochemical changes in the cerebrospinal fluid (CSF) could reflect pathophysiological processes in Alzheimer's disease (AD). However, it is still not clear how these processes correlate with grey matter (GM) volume and microstructural changes in the brain. OBJECTIVE: To assess the relationship between CSF biomarkers and structural brain changes in AD. DESIGN AND SETTING: Cross-sectional study in a memory clinic-based sample. SUBJECTS: A total of 78 subjects were included in the study: 22 with subjective cognitive impairment (SCI), 35 with mild cognitive impairment (MCI) and 21 with AD. MAIN OUTCOME MEASURES: Voxel-wise correlations between CSF biomarkers, including ß-amyloid42 (Aß42), tau phosphorylated at position threonine 181 and total tau protein, and GM volume, self-diffusion fractional anisotropy (FA) and mean diffusivity (MD) maps using voxel-based morphometry and tract-based spatial statistical analyses. FA and MD maps were obtained using diffusion tensor imaging. RESULTS: In the whole sample (patients with SCI, MCI and AD), there was positive correlation between GM volume and Aß42 concentration, and negative correlation with total tau protein. Higher FA was only related to higher concentration of Aß42. MD showed significant negative correlation with Aß42 and positive correlation with T-tau levels. The majority of brain regions with significant correlation with CSF biomarkers overlapped with the default mode network and extended to the adjacent white matter. CONCLUSIONS: Early AD pathological changes can be detected with voxel-based morphometric analysis and diffusion tensor imaging measurements. Furthermore, there was an association between CSF AD biomarkers and structural brain changes in areas related to the default mode network.

Influence of age, disease onset and ApoE4 on visual medial temporal lobe atrophy cut-offs.

BACKGROUND: Visual assessment of medial temporal lobe atrophy (MTA; range 0-4, from no atrophy to increasing atrophy of the choroid fissure, temporal horns and hippocampus) is a sensitive radiological marker of Alzheimer's disease (AD). One of the critical elements for visual MTA assessment is the cut-off score that determines deviation from normality. METHODS: In this study, we assessed the sensitivity and specificity of different MTA cut-off scores to classify control subjects, individuals with mild cognitive impairment (MCI) and AD patients from two large independent cohorts, AddNeuroMed and Alzheimer's Disease Neuroimaging Initiative. Of note, we evaluated the effects of clinical, demographic and genetic variables on the classification performance according to the different cut-offs. RESULTS: A cut-off of ≥1.5 based on the mean MTA scores of both hemispheres showed higher sensitivity in classifying patients with AD (84.5%) and MCI subjects (75.8%) who converted to dementia compared to an age-dependent cut-off. The age-dependent cut-off showed higher specificity or ability to correctly identify control subjects (83.2%) and those with MCI who remained stable (65.5%). Increasing age, early-onset disease and absence of the ApoE ε4 allele had a stronger influence on classifications using the ≥1.5 cut-off. Above 75 years of age, an alternative cut-off of ≥2.0 should be applied to achieve a classification accuracy for both patients with AD and control subjects that is clinically useful. CONCLUSION: Clinical, demographic and genetic variables can influence the classification of MTA cut-off scores, leading to misdiagnosis in some cases. These variables, in addition to the differential sensitivity and specificity of each cut-off, should be carefully considered when performing visual MTA assessment.

Classification and prediction of clinical diagnosis of Alzheimer's disease based on MRI and plasma measures of α-/γ-tocotrienols and γ-tocopherol.

BACKGROUND: The aim of this study was to evaluate the accuracy of combined structural magnetic resonance imaging (MRI) measures and plasma levels of vitamin E forms, including all eight natural vitamin E congeners (four tocopherols and four tocotrienols) and markers of vitamin E oxidative/nitrosative damage, in differentiating individuals with Alzheimer's disease (AD) and mild cognitive impairment (MCI) from cognitively intact control (CTL) subjects. METHODS: Overall, 81 patients with AD, 86 with MCI and 86 CTL individuals were enrolled from the longitudinal multicentre AddNeuroMed study. MRI and plasma vitamin E data were acquired at baseline. MRI scans were analysed using Freesurfer, an automated segmentation scheme which generates regional volume and cortical thickness measures. Orthogonal partial least squares to latent structures (OPLS), a multivariate data analysis technique, was used to analyse MRI and vitamin E measures in relation to AD and MCI diagnosis. RESULTS: The joint evaluation of MRI and plasma vitamin E measures enhanced the accuracy of differentiating individuals with AD and MCI from CTL subjects: 98.2% (sensitivity 98.8%, specificity 97.7%) for AD versus CTL, and 90.7% (sensitivity 91.8%, specificity 89.5%) for MCI versus CTL. This combination of measures also identified 85% of individuals with MCI who converted to clinical AD at follow-up after 1 year. CONCLUSIONS: Plasma levels of tocopherols and tocotrienols together with automated MRI measures can help to differentiate AD and MCI patients from CTL subjects, and to prospectively predict MCI conversion into AD. Our results suggest the potential role of nutritional biomarkers detected in plasma-tocopherols and tocotrienols-as indirect indicators of AD pathology, and the utility of a multimodality approach.

An MRI-based index to measure the severity of Alzheimer's disease-like structural pattern in subjects with mild cognitive impairment.

BACKGROUND: Structural magnetic resonance imaging (MRI) is sensitive to neurodegeneration and can be used to estimate the risk of converting to Alzheimer's disease (AD) in individuals with mild cognitive impairment (MCI). Brain changes in AD and prodromal AD involve a pattern of widespread atrophy. The use of multivariate analysis algorithms could enable the development of diagnostic tools based on structural MRI data. In this study, we investigated the possibility of combining multiple MRI features in the form of a severity index. METHODS: We used baseline MRI scans from two large multicentre cohorts (AddNeuroMed and ADNI). On the basis of volumetric and cortical thickness measures at baseline with AD cases and healthy control (CTL) subjects as training sets, we generated an MRI-based severity index using the method of orthogonal projection to latent structures (OPLS). The severity index tends to be close to 1 for AD patients and 0 for CTL subjects. Values above 0.5 indicate a more AD-like pattern. The index was then estimated for subjects with MCI, and the accuracy of classification was investigated. RESULTS: Based on the data at follow-up, 173 subjects converted to AD, of whom 112 (64.7%) were classified as AD-like and 61 (35.3%) as CTL-like. CONCLUSION: We found that joint evaluation of multiple brain regions provided accurate discrimination between progressive and stable MCI, with better performance than hippocampal volume alone, or a limited set of features. A major challenge is still to determine optimal cut-off points for such parameters and to compare their relative reliability.

Multivariate classification of patients with Alzheimer's and dementia with Lewy bodies using high-dimensional cortical thickness measurements: an MRI surface-based morphometric study.

CONTEXT: Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) are the most common neurodegenerative dementia types. It is important to differentiate between them because of the differences in prognosis and treatment approaches. OBJECTIVE: Investigate if sparse partial least squares (SPLS) classification of cortical thickness measurements could differentiate between AD and DLB. METHODS: Two independent cohorts without MR-protocol alignment in Norway and Slovenia with 97 AD and DLB subjects were enrolled. Cortical thickness measurements acquired with Freesurfer were used in subsequent SPLS classification runs. The cohorts were analyzed separately and afterwards combined. The models were trained with leave-one-out cross validation and test datasets where used when available. To study the impact of MR-protocol alignment, the classifiers were additionally tested on sets drawn exclusively from the independent cohorts. RESULTS: The obtained sensitivity/specificity/AUC values were 94.4/88.89/0.978 and 88.2/94.1/0.969 in the Norwegian and Slovenian cohorts, respectively. Both cohorts showed AD-associated pattern of thinning in mid-anterior temporal, occipital and subgenual cingulate cortex, whereas the pattern supportive for DLB included thinning in dorsal cingulate, posterior temporal and lateral orbitofrontal regions. When combining the cohorts, sensitivity/specificity/AUC were 82.1/85.7/0.948 for the training and 77.8/75/0.731 for the testing datasets with the same pattern-of-difference. The models tested on datasets drawn exclusively from the independent cohorts did not produce adequate accuracy. CONCLUSION: SPLS classification of cortical thickness is a good method for differentiating between AD and DLB, relatively stable even for mixed data, but not when tested on completely independent data drawn from different cohorts (without MR-protocol alignment).

CERAD Neuropsychological Total Scores Reflect Cortical Thinning in Prodromal Alzheimer's Disease.

BACKGROUND: Sensitive cognitive global scores are beneficial in screening and monitoring for prodromal Alzheimer's disease (AD). Early cortical changes provide a novel opportunity for validating established cognitive total scores against the biological disease markers. METHODS: We examined how two different total scores of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) battery and the Mini-Mental State Examination (MMSE) are associated with cortical thickness (CTH) in mild cognitive impairment (MCI) and prodromal AD. Cognitive and magnetic resonance imaging (MRI) data of 22 progressive MCI, 78 stable MCI, and 98 control subjects, and MRI data of 103 AD patients of the prospective multicenter study were analyzed. RESULTS: CERAD total scores correlated with mean CTH more strongly (r = 0.34-0.38, p < 0.001) than did MMSE (r = 0.19, p = 0.01). Of those vertex clusters that showed thinning in progressive MCI, 60-75% related to the CERAD total scores and 3% to the MMSE. CONCLUSION: CERAD total scores are sensitive to the CTH signature of prodromal AD, which supports their biological validity in detecting early disease-related cognitive changes.

A comparison between volumetric data generated by voxel-based morphometry and manual parcellation of multimodal regions of the frontal lobe.

BACKGROUND AND PURPOSE: Volumetric measurements on structural MR images are an established method to investigate pathology-related volume changes in cortex. Manual volumetric methods have sometimes been referred to as the reference standard for quality control of automatic volumetric methods. While some automatic methods, like VBM, may rely on a template, manual methods use sulci as indirect landmarks for the subdivision of cortex. The purpose of this study was to compare volumetric data generated by MM and VBM on 4 multimodal regions in the frontal lobe. MATERIALS AND METHODS: We investigated 4 multimodal frontocortical regions by MM and VBM in patients with frontotemporal lobar degeneration and Alzheimer disease and controls. RESULTS: MM and VBM results were highly correlated for dorsolateral prefrontal cortex, orbitofrontal cortex, and hippocampus, but not for the dorsal and rostral anterior cingulate. VBM results were more consistent with results from previous studies on cingulate in frontotemporal lobar degeneration. Our results may potentially be explained by 2 factors. First, the volume of small cortical regions may be more affected by anatomic variability than large regions in the MM. Second, it has been shown that the location of multimodal cytoarchitectonic areas, such as the cingulate cortex, may be difficult to predict by the appearance of sulci and gyri. CONCLUSIONS: While both VBM and the MM may do equally poorly in predicting cytoarchitecture, the MM may add additional unrelated variance caused by anatomic variability. Thus, paradoxically, the higher anatomic precision of the MM may potentially cause a weaker relation to cytoarchitecture.

Suppressive effects of a quinoxaline-analogue (Rob 803) on pathogenic immune mechanisms in collagen-induced arthritis.

The anti-arthritic effects of the synthetic compound 9-chloro-2,3 dimethyl-6-(N,N-dimetylamino-2-oxoethyl)-6H-indolo[2,3-b] quinoxaline (Rob 803) was evaluated by treating Dark Agouti rats with collagen-induced arthritis using three different protocols. Daily subcutaneous treatment with 40 mg/kg/day of Rob 803 from the day of immunization and 14 days forward suppressed arthritis severity significantly and delayed the onset of clinical arthritis. In contrast, similar treatment initiated when individual rats had developed clinical disease (at a score of 2 points) did not suppress disease. Oral treatment with 35 mg/kg/day of Rob 803 from the day of immunization and 21 days forward resulted in a trend towards disease suppression. In vitro analysis of rats treated subcutaneously with Rob 803 revealed an inhibition of T cell proliferation but no effect on the generation of an anti-CII immunoglobulin G response. Further in vitro analysis demonstrated that Rob 803 also inhibited the generation of nitric oxide in macrophages, although at higher concentrations than needed for inhibitory effects on T cell proliferation. Thus we report that early subcutaneous administration of the synthetic substance Rob 803 has anti-rheumatic effects that are probably mediated by affecting the proliferative capacity of lymph node T cells. Rob 803 should be considered as a new candidate substance for anti-rheumatic treatment.

Acid-base analysis of individuals following two weight loss diets.

OBJECTIVE: To examine the effects of low-carbohydrate, ketogenic (LCKD) and low-fat (LFD) diets on acid-base status. DESIGN: Prospective analysis of volunteers from two clinical trials. PARTICIPANTS: Subset of 39 volunteers from a randomized trial comparing the effects of an LCKD with an LFD, and a single-arm trial of an LCKD. SETTING: Outpatient research clinic. INTERVENTION: LCKD (initially <20 g of carbohydrate daily) or LFD (<30% of energy from fat, 500-1000 kcal energy reduction) instruction. MEASUREMENTS: Arterial blood gas analysis, serum chemistries (electrolytes, urea nitrogen/creatinine, glucose, ketone bodies, lactate), anion gap, and urine ketone bodies measured at weeks 0, 2, 8, and 24. RESULTS: Participants had a mean (+/-standard deviation) age of 43.5+/-9.3 years; 28 (72%) were female, 29 (74%) were Caucasian. Using linear mixed-model analysis to examine blood test changes from baseline to 24 weeks, the LFD group experienced a decrease in arterial blood pH from a mean of 7.43 at week 0 to 7.40 at week 24 (P=0.03), and the LCKD group experienced a decrease from 7.42 at week 0 to 7.40 at week 24 (P=0.01). The lowest pH measurements observed were 7.34 in the LFD group and 7.37 in the LCKD group. Although serum bicarbonate appeared to decrease from baseline at weeks 2 and 8 in the LCKD group, the change at 24 weeks was not statistically significant in either diet group, and only four of 131 (two of 92 from the LCKD group) measurements were less than 22 mmol/l. The proportion of participants with elevated urine and serum ketone body levels rose in the LCKD group only, was highest at week 2, and decreased over the subsequent time points. CONCLUSION: In individuals following an LCKD or an LFD, blood pH decreased mildly and the LCKD group experienced a small, transient decrease in serum bicarbonate in conjunction with mild ketosis. This suggests that an LCKD induced a mild compensated metabolic acidosis, but no individual showed evidence of significant metabolic derangement.

Arthritogenicity of collagen type II is increased by chlorination.

During inflammation, activated neutrophils, monocytes and macrophages produce and release myeloperoxidase (MPO). MPO converts hydrogen peroxide to hypochlorous acid, a highly reactive and oxidizing agent. Proteins subjected to hypochlorous acid become chlorinated. We analysed how chlorination of the cartilage antigen collagen type II (CII) affects its immunogenic and arthritogenic properties by studying immune responses to chlorinated CII in comparison to immune responses to CII and by studying the development of arthritis in rats immunized with CII-Cl. CII-Cl immunization of LEW.1AV1 rats caused a 100% incidence of arthritis with a mean maximum score of 9.2 (maximal score possible 16). The same dose of non-chlorinated CII did not induce arthritis at all. Rats immunized with CII-Cl developed high anti-CII-Cl IgG titres and also developed IgG antibodies recognizing the non-chlorinated form of CII. Analysis of cytokine mRNA expression in lymph nodes 10 days after immunzation revealed an increased expression of interferon (IFN)-gamma mRNA and interleukin (IL)-1beta mRNA in CII-Cl-immunized rats compared to CII-immunized rats. Thus, chlorination of CII increased its immunogenicity as well as its arthritogenicity. As neutrophils, monocytes and macrophages are abundant cells in arthritic joints of patients with rheumatoid arthritis, chlorination might be a mechanism by which immunoreactivity to CII is induced and by which chronic joint inflammation is supported.

Diet therapy for narcolepsy.

The effects of a low-carbohydrate, ketogenic diet (LCKD) on sleepiness and other narcolepsy symptoms were studied. Nine patients with narcolepsy were asked to adhere to the Atkins' diet plan, and their symptoms were assessed using the Narcolepsy Symptom Status Questionnaire (NSSQ). The NSSQ-Total score decreased by 18% from 161.9 to 133.5 (p = 0.0019) over 8 weeks. Patients with narcolepsy experienced modest improvements in daytime sleepiness on an LCKD.

Alteration of an autoantigen by chlorination, a process occurring during inflammation, can overcome adaptive immune tolerance.

Autoimmune diseases are characterized by chronic inflammation in target organs and immunoreactivity towards one or multiple autoantigens. Several potential mechanisms of tolerance breaking have been postulated, one being inflammation-associated events. We have investigated whether chlorination of an autoantigen can lead to disruption of self-tolerance. Chlorination of antigens might occur during inflammation via the granulocyte-specific, myeloperoxidase-catalysed conversion of hydrogen peroxide to hypochlorous acid (HOCl). HOCl, being a strong oxidant, reacts with proteins both within cellular phagosomes and in the immediate extracellular environment. By immunizing Lew.1AV1 rats with chlorinated or unmodified rat serum albumin (RSA), we could detect tolerance-breaking effects of chlorination. RSA is a systemic autoantigen in rat not inducing antibody production upon immunization in its unmodified form. Rats immunized with chlorinated RSA (RSA-Cl) developed high titres of immunoglobulin G (IgG) specific for RSA-Cl which cross-reacted with native RSA. T cells reactive with both RSA-Cl and RSA were detected by [(3)H]-thymidine incorporation. We hence speculated that immunological tolerance established for unmodified proteins, during certain circumstances such as inflammation, might be broken by induced protein chlorination. T cells specific for the chlorinated protein can confer help to B cells recognizing both the chlorinated and the native form of the protein, leading to the formation of high-affinity autoreactive antibodies and possibly autoimmune disease.