Showing papers in "Journal of Alzheimer's Disease in 2004"

Curcumin interaction with copper and iron suggests one possible mechanism of action in Alzheimer's disease animal models.

Abstract: Curcumin is a polyphenolic diketone from turmeric. Because of its anti-oxidant and anti-inflammatory effects, it was tested in animal models of Alzheimer's disease, reducing levels of amyloid and oxidized proteins and preventing cognitive deficits. An alternative mechanism of these effects is metal chelation, which may reduce amyloid aggregation or oxidative neurotoxicity. Metals can induce Abeta aggregation and toxicity, and are concentrated in AD brain. Chelators desferrioxamine and clioquinol have exhibited anti-AD effects. Using spectrophotometry, we quantified curcumin affinity for copper, zinc, and iron ions. Zn2+ showed little binding, but each Cu2+ or Fe2+ ion appeared to bind at least two curcumin molecules. The interaction of curcumin with copper reached half-maximum at approximately 3-12 microM copper and exhibited positive cooperativity, with Kd1 approximately 10-60 microM and Kd2 approximately 1.3 microM (for binding of the first and second curcumin molecules, respectively). Curcumin-iron interaction reached half-maximum at approximately 2.5-5 microM iron and exhibited negative cooperativity, with Kd1 approximately 0.5-1.6 microM and Kd2 approximately 50-100 microM. Curcumin and its metabolites can attain these levels in vivo, suggesting physiological relevance. Since curcumin more readily binds the redox-active metals iron and copper than redox-inactive zinc, curcumin might exert a net protective effect against Abeta toxicity or might suppress inflammatory damage by preventing metal induction of NF-kappaB.

Aluminium, iron, zinc and copper influence the in vitro formation of amyloid fibrils of Abeta42 in a manner which may have consequences for metal chelation therapy in Alzheimer's disease.

Abstract: Metals are found associated with beta-pleated sheets of Abeta42 in vivo and may be involved in their formation. Metal chelation has been proposed as a therapy for Alzheimer's disease on the basis that it may safely dissolve precipitated Abeta peptides. We have followed fibrillisation of Abeta42 in the presence of an additional metal ion (Al(III), Fe(III), Zn(II), Cu(II)) over a period of 32 weeks and we have investigated the dissolution of these aged peptide aggregates in the presence of both desferrioxamine (DFO) and ethylenediaminetetraacetic acid (EDTA). Abeta42 either alone or in the presence of Al(III) or Fe(III) formed beta-pleated sheets of plaque-like amyloids which were dissolved upon incubation with either chelator. Zn(II) inhibited whilst Cu(II) prevented the formation of beta-pleated sheets of Abeta42and neither of these influences were affected by incubation of the aged peptide aggregates with either DFO or EDTA. Freshly prepared solutions of Abeta42 either alone or in the presence of added Al(III) or Fe(III) did not form beta-pleated amyloid in the presence of DFO when incubated for up to 8 weeks. EDTA did not prevent beta-pleated amyloid formation in the same treatments and promoted beta-pleated amyloid formation in the presence of either Zn(II) or Cu(II). The presence of significant concentrations of Al(III) and Fe(III) as contaminants of 'Abeta42 only' preparations suggested that both of these metals were involved in either triggering the formation or stabilising the structure of beta-pleated amyloid. If the formation of such amyloid is critical to the aetiology of AD then the chelation of Al(III) and Fe(III) may prove to be a protective mechanism whilst the chelation of Cu(II) and Zn(II) without also chelating Al(III) and Fe(III) might actually exacerbate the condition.

Lipid peroxidation and oxidative imbalance: early functional events in Alzheimer's disease.

Abstract: Alzheimer's disease (AD) is a growing public health problem worldwide. Clinically, AD is a progressive neurodegenerative disorder characterized by a global cognitive decline. Accumulating evidence indicates that reactive oxygen species-mediated reactions, particularly of neuronal lipids, are extensive in those AD brain areas directly involved in the disease processes. Traditional views claim that oxidative-mediated tissue injury in the AD brain is the result of neurodegeneration. In recent years, numerous investigations have pointed to the functional importance of oxidative imbalance as a crucial event in mediating AD pathogenesis. The availability of specific and sensitive markers to monitor in vivo oxidative stress, in combination with studies performed in living patients with clinical diagnosis of AD are helping us to elucidate these issues. The evidence we have accumulated so far clearly indicates that oxidative imbalance and subsequent oxidative stress are early events during the evolution of the disease, and secondary to specific mechanism(s) present in AD but not in other neurodegenerative diseases. These new concepts implicate that this phenomenon may play a more important role in AD pathogenesis than previously anticipated, and that any therapeutic intervention targeting oxidative stress should be initiated at the earliest possible stage of the disease.

Demonstration of a role for α-synuclein as a functional microtubule-associated protein

Abstract: α-Synuclein is a major constituent of pathological intracellular inclusion bodies, a common feature of several neu- rodegenerative diseases. Two missense mutations in the α-synuclein gene have been identified in confirmed autosomal-dominant familial Parkinson's disease, which segregate with the illness. However, the physiological function of α-synuclein remains unknown. After biochemical investigations we have revealed tubulin to be an α-synuclein associated/binding protein. Here, we show that α-synuclein induces polymerization of purified tubulin into microtubules. Mutant forms of α-synuclein lose this potential. The binding site of α-synuclein to tubulin is identified, and co-localization of α-synuclein with microtubules is shown in cultured cells. To our knowledge, this is the first demonstration of microtubule-polymerizing activity of α-synuclein. Now we can see a striking resemblance between α-synuclein and tau: both have the same physiological function and pathological features, making abnormal structures in diseased brains known as synucleinopathies and tauopathies. The discovery of a physiological role for α-synuclein may provide a new dimension in researches into the mechanisms of α-synuclein-associated neurodegenerative diseases.

Oxidative stress and neuroinflammation in Alzheimer's disease and amyotrophic lateral sclerosis: common links and potential therapeutic targets

Abstract: Many neurological diseases, including Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS), are now recognized to share atypical inflammatory reactions as a major pathological feature. Neuroinflammation can both be a cause, and a consequence, of chronic oxidative stress. Cytokine-stimulated microglia generate copious amounts of reactive oxygen and reactive nitrogen species, creating a stress upon ambient neurons. Conversely, oxidants can stimulate pro-inflammatory gene transcription in glia, leading to various inflammatory reactions. This review compares literature regarding neuroinflammation in AD and ALS, with special emphasis on roles played by tumor necrosis factor alpha (TNFalpha) and aberrant arachidonic acid metabolism in the genesis of chronic oxidative conditions. Based on our observations made in the G93A-SOD1 mouse model of ALS, and a body of Alzheimer's disease findings, we hypothesize a prominent pathological role for the TNFalpha-signaling axis and neuroinflammation in the pathogenesis of both diseases. A discussion is made regarding the relevance of neuroinflammation to potential therapeutic implications for both ALS and AD.

Colostrinin (a naturally occurring, proline-rich, polypeptide mixture) in the treatment of Alzheimer's disease.

Abstract: This study was designed to confirm or negate findings from earlier trials demonstrating that Colostrinin, a novel compound derived from ewes' colostrum, has potential in the treatment of mild or moderate Alzheimer's Disease (AD). 105 patients were recruited from six psychiatric centres in Poland. The trial consisted of a 15 week double-blind phase comparing Colostrinin with placebo, followed by a second 15 week open labelled phase when all patients received Colostrinin. The dosage of Colostrinin was 100 microg on alternate days for three weeks followed by two weeks drug-free. This cycle was repeated three times for each phase. The primary outcome measures used were Alzheimer's Disease Assessment Scale-cognitive portion (ADAS-cog) and Clinical Global Impression of Change (CGIC). Secondary outcome measures were Instrumental Activities of Daily Living (IADL); Mini-Mental State Examination (MMSE); ADAS-non cognitive test (ADAS-non cog); and overall Patient Response. The main outcome measures were assessed at week 15 when active was compared with placebo but all parameters were evaluated at baseline, week 15 and week 30. Two separate statistical analyses were undertaken, a Full Sample Analysis (FSA) in which all missing values were replaced with the worst result observed and a Valid for Efficacy (VFE) analysis in which those patients who had serious protocol violations were excluded. This resulted in 14 patients being excluded from the VFE-analysis. The FSA analysis at week 15 showed a stabilizing effect of Colostrinin on cognitive function in ADAS-cog (p = 0.02) and on daily function in IADL (p = 0.02). The overall patient response was also in favour of the active (p = 0.03). Patients graded as mild on entry also showed a superior response of ADAS-cog compared with more advanced cases (p = 0.01). Evidence from this study indicates an early beneficial effect on cognitive symptoms and daily function. Colostrinin has potential value in the treatment AD.

Overexpression of ubiquilin decreases ubiquitination and degradation of presenilin proteins.

Abstract: Mutations in presenilin proteins (PS1 and PS2) are associated with most cases of early-onset Alzheimer's disease. Several proteins appear to regulate accumulation of PS proteins in cells. One such protein is ubiquilin-1, which increases levels of coexpressed PS2 protein in a dose-dependent manner. We now report that overexpression of ubiquilin-2, which is 80% identical to ubiquilin-1, also increases the levels of coexpressed PS1 and PS2 proteins in cells. To investigate the mechanism by which ubiquilin proteins increase levels of PS proteins, we examined how overexpression of ubiquilin-1, which possesses all of the key signature motifs present in ubiquilin proteins, affects PS2 gene transcription and PS2 protein turnover and ubiquitination. HeLa cells overexpressing both PS2 and ubiquilin-1 had PS2 mRNA levels lower than HeLa cells overexpressing PS2 alone, indicating that ubiquilin-1 overexpression, in fact, decreases PS2 transcription. Cells overexpressing ubiquilin-1 and PS2 displayed decreased turnover of high molecular weight (HMwt) forms of PS2 but not of full-length PS2 proteins. The reduced turnover of HMwt PS2 proteins appears to be mediated by the binding of the ubiquitin-associated domain (UBA) of ubiquilin to ubiquitin chains conjugated onto PS2 proteins. Immunoprecipitation studies indicated that ubiquilin-1 overexpression decreases ubiquitination of coexpressed PS2 proteins, suggesting that binding of ubiquilin might block ubiquitin chain elongation. Consistent with this model, we found that the UBA domain of ubiquilin-1 binds poly-ubiquitin chains in vitro. In addition, we show that ubiquilin proteins colocalize with ubiquitin-immunoreactive structures in cells and that ubiquilin proteins are present within the inner core of aggresomes, which are structures associated with accumulation of misfolded proteins in cells. Our results suggest that ubiquilin proteins play an important role in regulating PS protein levels in cells.

Alzheimer disease: evidence for a central pathogenic role of iron-mediated reactive oxygen species.

Abstract: Free radical formation, abnormalities in iron and copper distribution, and metal-catalyzed oxidation have all been noted in Alzheimer disease and are thought to play an important role in disease pathogenesis. Metal-catalyzed hydroxyl radical formation results in damage to every category of macromolecule found in the vulnerable neuronal populations in Alzheimer disease. In fact, redox activity resides within the cytosol of vulnerable neurons. Since oxidative damage represents one of the earliest pathological changes in Alzheimer disease, it is likely that aberrant redox activity is among the earliest changes in the transition to the disease state. In this review, we consider the wealth of evidence implicating a central role for metals in Alzheimer disease.

Development of a safe oral Abeta vaccine using recombinant adeno-associated virus vector for Alzheimer's disease

Abstract: A new oral vaccine for Alzheimer's disease was developed using recombinant adeno-associated virus vector carrying Abeta cDNA (AAV/Abeta). Oral administration of the vaccine without adjuvant induced the expression and secretion of Abeta1-43 or Abeta1-21 in the epithelial cell layer of the intestine in amyloid precursor protein transgenic mice. Serum antibody levels were elevated for more than six months, while T cell proliferative responses to Abeta was not detected. Brain Abeta burden was significantly decreased compared to the control without inflammatory changes. This oral AAV/Abeta vaccine seems to be promising for prevention and treatment of Alzheimer's disease.

The potential role of tau protein O-glycosylation in Alzheimer's disease.

Abstract: Single O-linked N-acetylglucosamine (O-GlcNAc) sugar residues can compete with phosphate groups to occupy specific sites on certain nuclear and cytosolic proteins Here we show that inhibiting cellular kinase activities resulted in changes in protein O-glycosylation levels in heat-stable cytoskeletal protein fractions derived from primary neuronal cells As increased phosphorylation of the microtubule-associated protein tau is one of the pathological hallmarks of Alzheimer's disease and glycosylation may play an influential role in this process We observed a significant decrease in the protein O-GlcNAc glycosylation of a tau-enriched cytoskeletal fraction generated from AD post-mortem brain samples as compared with control, suggesting an inverse relationship between the two post-translational modifications Finally, cells transfected with the cDNA coding for O-GlcNAc transferase (OGT) displayed altered tau phosphorylation patterns as compared with control cells, suggesting that changes in tau glycosylation may influence its phosphorylation state The specificity of the changes in the phosphorylation of individual amino acid residues provides evidence for a targeted O-glycosylation of tau

Rodent Abeta(1-42) exhibits oxidative stress properties similar to those of human Abeta(1-42): Implications for proposed mechanisms of toxicity.

Abstract: Alzheimer's disease is a neurodegenerative disorder associated with aging and cognitive decline Amyloid beta peptide (1-42) [Abeta(1-42)] is a primary constituent of senile plaques - a hallmark of Alzheimer's disease - and has been implicated in the pathogenesis of the disease Previous studies have shown that methionine residue 35 of beta(1-42) may play a critical role in Abeta(1-42)-mediated oxidative stress and neurotoxicity Several additional mechanisms of neurotoxicity have been proposed, including the role of Cu(II) binding and reduction to produce hydrogen peroxide and the role of peptide aggregation It has been reported that rodent Abeta is less likely to form larger beta-sheet structures, and consequently, large aggregates As a consequence of the lack of deposition of the peptide in rodent brain, rodent Abeta has been proposed to be non-toxic Additionally, the sequence of the rodent variety of Abeta(1-42) contains three amino acid substitutions compared to the human sequence These substitutions include the shift of arginine 5, trysosine 10, and histidine 13 to glycine, phenylalanine, and arginine, respectively This shift in sequence within the Cu(II) binding region of the peptide results in a decrease in the ability of the rodent Abeta peptide to reduce Cu(II) to Cu(I) compared to the human Abeta peptide As a result of the effect of the amino acid variations on the ability of the rodent peptide to reduce Cu(II) to Cu(I) compared to the human peptide, the rodent beta has been proposed to lack oxidative stress properties In this study, the oxidative stress and neurotoxic properties of rodent beta(1-42) [Abeta(1-42)Rat] were evaluated and compared to those of human Abeta(1-42) Both human Abeta(1-42) and beta(1-42)Rat were found to have a significant effect on neuronal DNA fragmentation, loss of neuritic networks, and cell viability beta(1-42) Rat was found to cause a significant increase in both protein oxidation and lipid peroxidation, similar to Abeta(1-42), both of which were inhibited by the lipid-soluble, chain breaking antioxidant vitamin E, suggesting that reactive oxygen species play a role in the Abeta-mediated toxicity Taken together, these results suggest that Cu(II) reduction may not play a critical role inbeta(1-42)Rat-induced oxidative stress, and that the oxidative stress exhibited by this peptide may be a consequence of the presence of methionine 35, similar to the findings associated with the native human beta(1-42) peptide

Oestrogen replacement therapy may improve memory functioning in the absence of APOE e4

Abstract: There is currently intense controversy regarding the use of hormone replacement therapy (HRT) in postmenopausal women, in relation to its therapeutic efficacy in Alzheimer's disease (AD). It has been suggested that the benefits of HRT may be modified by apolipoprotein E (APOE) genotype (the major genetic risk factor for AD). Here we report the findings of the first study designed to systematically explore the interaction of (a) oestrogen replacement therapy (ERT) and (b) possession of an e4 allele of APOE on specific elements of episodic learning and memory that are commonly used indices of age-related cognitive decline. This data represents a cross-sectional analysis of the interaction of ERT and APOE genotype on learning and memory in a cohort of 181 healthy postmenopausal women [ERT users (n = 101, mean age 65.40 ± 6.34); ERT non-users (n = 80, mean age 67.03 ± 6.80)] residing in Perth, Western Australia. The highest level of learning (trials 2-5; P < 0.05) and memory (e.g. total number of items recalled; P < 0.05) performance was observed in women taking ERT who were not carriers of the APOE e4 allele. APOEe4 carriers receiving ERT performed no better on episodic memory testing than APOE e4 carriers who were not receiving ERT. These cognitive differences related to genetic profile, were noted on both recall and recognition (P = 0.005) tests of memory. The findings have significance for evaluating whether and when ERT may be clinically indicated. Specifically, ERT may benefit the cognitive functioning of women not carrying the APOE e4 allele.

Suppression of longitudinal increase in CSF F2-isoprostanes in Alzheimer's disease.

Abstract: We report the first longitudinal analysis of cerebrospinal fluid (CSF) F2-isoprostanes (IsoPs), quantitative in vivo biomarkers of lipid peroxidation, in patients with mild Alzheimer's disease (AD) CSF F2-IsoPs (i) were significantly increased in patients followed over one year, (ii) correlated with some clinical indices of dementia following correction for variation in ventricular enlargement, and (iii) were significantly lower in patients who used both alpha-tocopherol and vitamin C

Rat transgenic models with a phenotype of intracellular Aβ accumulation in hippocampus and cortex

Abstract: In this communication we report the characterization of several transgenic rat lines expressing human AbetaPP carrying the Swedish and Indiana mutations (coded UKUR28), the human presenilin 1 transgene with the 'Finn' mutation (coded UKUR19) and double transgenic rats expressing both transgenes (coded UKUR25). In these Tg rats, the AbetaPP and PS1 transgene expression was largely restricted to the hippocampus and neocortex. The PS1 transgenic rats did not produce visible changes in Abeta immunoreactivity. The AbetaPP transgenic rats (both the single Tg UKUR28, and double Tg UKUR25) generated a phenotype of intra-neuronalbeta accumulation without plaque formation and with no increased immunoreactivity for AbetaPP amino and carboxyl-terminal epitopes. This phenotype was apparent as early as 6 months of age in the transgenic rat lines carrying the human AbetaPP transgene. No senile plaques of aggregated Abeta were observed in any of the transgenic lines generated, up to 24 months of age. The hAbetaPP single homozygous Tg line (UKUR28) showed an increase in ERK2, without changes in glycogen synthase kinase 3 (GSK3) activity. A preliminary protein analysis of the hippocampus of the double transgenic rat (UKUR25) by mass spectrometry showed differences in the protein profile between this transgenic line and controls.

Oxidative stress in mild cognitive impairment and Alzheimer disease: a continuum.

Abstract: Although several studies show the importance of oxidative stress in the pathogenesis of Alzheimer's disease (AD), there are few evidences on the role of free radicals in Mild Cognitive Impairment (MCI). Our results showing a marked decrease of the main components of the antioxidant defense system of the organism support the hypothesis that in MCI there is a condition of oxidative stress. This work also gives an overview on the existing evidence of the early occurrence of oxidative processes in the development of dementing disorders of the Alzheimer type. Since MCI represents a condition of increased risk for AD, use of antioxidants in MCI could be of importance for prevention.

Advanced glycation endproduct precursor alters intracellular amyloid- β/AβPP carboxy-terminal fragment aggregation and cytotoxicity

Abstract: Carbonyl stress from products of lipid peroxidation, such as 4-hydroxynonenal (HNE), and products of sugars in diabetes mellitus, such as methylglyoxal (MG) and glyoxal (G), may contribute to neurodegeneration in Alzheimer's disease (AD). We tested the hypothesis that these carbonyls alter the proposed central pathogenic mechanism of AD, intracellular amyloid-beta (A beta)-mediated cytotoxicity, using a human neuroblastoma cell line that conditionally expresses carboxy-terminal fragments (CTFs) of the amyloid precursor protein. HNE was a potent cytotoxin, whereas G was mildly cytotoxic; cytotoxicity from each was independent of A beta/CTF expression and not altered by alpha-tocopherol. In contrast, MG cytotoxicity was enhanced by the induced expression of A beta/CTFs and suppressed by alpha-tocopherol. alpha-tocopherol cytoprotection was accompanied by decreased A beta/CTF aggregation. G also promoted beta/CTF aggregation but by mechanisms unaffected by alpha-tocopherol treatment. Our findings showed that A beta/CTF aggregation and cytotoxicity may be profoundly altered by aldehydes associated with diabetes and that in the case of MG, this process is suppressed by alpha-tocopherol. Moreover, our results suggest that while intracellular aggregation of A beta/CTFs may be necessary for the development of toxicity attributable to their expression in this model, the presence of high-molecular weight aggregated A beta/CTFs does not invariably lead to cytotoxicity.

Peripheral markers of oxidative stress and excitotoxicity in neurodegenerative disorders: tools for diagnosis and therapy?

Abstract: Oxidative stress has been implicated as a common pathogenetic mechanism in neurodegenerative disorders Central nervous system is particularly exposed to free radical injury, given its high metal content, which can catalyze the formation of oxygen free radicals, and the relatively low content of antioxidant defenses Indeed, several studies show markers of oxidative damage - lipid peroxidation, protein oxidation, DNA oxidation and glycoxidation markers - in brain areas affected by neurodegenerative disorders Oxidative stress damage is intimately linked to glutamate neurotoxicity - known as "excitotoxicity" An excessive concentration of extracellular glutamate over-activates ionotropic glutamate receptors, resulting in intracellular calcium overload and a cascade of events leading to neural cell death In this study we reviewed pathogenetic mechanisms that link oxidative stress and excitotoxicity in three neurodegenerative disorders (Alzheimer's disease, amyotrophic lateral sclerosis and Parkinson's disease) and described peripheral markers of these mechanisms, that may be analyzed in patients as possible diagnostic and therapeutic tools

Perspectives on the Amyloid-β Cascade Hypothesis

Abstract: For the better part of the past two decades, studies on the molecular, biochemical and cellular mechanisms of Alzheimer disease have focused on amyloid-beta protein, the major proteinaceous component of senile plaques. In fact, the Amyloid Cascade Hypothesis has come to dominate the field both in terms of proposed disease mechanism as well as potential for therapeutic intervention. In this review, we look at the Amyloid Cascade Hypothesis from the perspective of pathology, cell biology, and genetics. In all cases, alternate interpretations of old data as well as new evidence indicates that amyloid-beta, far from being the harbinger of disease, actually occurs secondary to more fundamental pathological changes and may even play a protective role in the diseased brain. These findings bring into serious doubt the validity of the Amyloid Cascade Hypothesis as the central cause of Alzheimer disease and, consequently, the potential usefulness of therapeutic targets against amyloid-beta.

Incubation of nerve endings with a physiological concentration of Aβ1-42 activates CaV2.2(N-Type)-voltage operated calcium channels and acutely increases glutamate and noradrenaline release

Abstract: We wish to understand the normal function of amyloid-beta peptides (Abeta) and to see if they destabilize neuronal calcium homeostasis [Mattson et al, J Neurosci 12 (1992), 376-389] We observed that a physiological concentration (10 nM) of Abeta1-42 increased both glutamate and noradrenaline exocytosis from rat cortical nerve endings at least in part by activation of N-type Ca2+ channels Abeta oligomers rather than monomers or fibrils probably are the most active form Three alternatively-proposed effects of Abeta (reactive oxygen species formation, membrane perforation, and disruption of Ca2+ stores) also were tested by incubating nerve endings with a relatively high (by this study's standards) concentration of Abeta1-42(100 nM) None of the three proposed effects were detected during these incubations These results support the hypothesis that persistent elevations of Abeta, which normally operates as a modulator of N-type voltage gated calcium channels, could increase internal nerve ending Ca2+ and excitatory neurotransmitter release to produce the early neurotoxic effects that eventually lead to Alzheimer's disease

Frontotemporal mild cognitive impairment

Abstract: Mild Cognitive Impairment appears to be a heterogeneous clinical entity comprising patients in the initial phases of distinct neurological disorders. Since frontotemporal dementia (FTD) is a relatively common neurodegenerative disease with an insidious onset, it might be possible to detect the patients in the initial phases of the disorder, before being demented. In the present work we proposed a set of criteria to identify patients with mild cognitive impairment of the frontotemporal type (FT-MCI), applied these criteria retrospectively to a large patient database, and evaluated the progression of the patients. Seven subjects fulfilling the proposed criteria for frontotemporal MCI were identified. They had symptoms of apathy, disinhibition, irritability and aggressiveness, untidiness, difficulties in decision making, obsessions and lack of concern for the others, for 1.5 +/- 0.8 years before the diagnosis of FT-MCI. Brain CT or MRI scan displayed fronto-temporal atrophy in five. Neuropsychological examination revealed deficits in tests dependent upon the frontal lobe, namely attention, verbal, motor and graphomotor initiatives and conceptual thinking. The patients kept their professional and daily activities, and were not demented. It was possible to have the follow-up of all patients. All but one patient diagnosed FT-MCI developed dementia of the frontotemporal type within 1.8 +/- 1.0 years. Application of the proposed criteria for FT-MCI, at least in this clinical neurological setting, can identify a group of patients with a high probability of further cognitive decline to dementia of the frontotemporal type.

Ageing and oxidative stress: a role for dolichol in the antioxidant machinery of cell membranes?

Abstract: Dolichol is a polyprenol compound broadly distributed in membranes, biosynthetized by the general isoprenoid pathway from acetate via mevalonate and farnesyl pyrophosphate. Dolichol lays inside the membrane between the two leaflets of the lipid bilayer very close to the tail of phospholipid fatty acids. No definite catabolic pathways for this molecule have yet been identified. Evidence is produced that dolichol levels increase dramatically with increasing age; that anti-ageing caloric restriction retards this age-associated change; that dolichol may act as a radical scavenger of peroxidized lipids belonging to the cell membranes. In view of the polyunsaturated fatty acids (PUFA), dolichol and Vitamin E location and stechiometry, it is proposed that molecules might interact each-other to form a highly matched free-radical-transfer chain, whose malfunctioning might be involved in statin toxicity and neurodegenerative diseases.

Fruit extracts antagonize Abeta- or DA-induced deficits in Ca2+ flux in M1-transfected COS-7 cells.

Abstract: Evidence suggests that there is a selective sensitivity to oxidative stress (OSS) among muscarinic receptor (MAChR) subtypes with M1, M2 and M4 showing > OSS than M3 or M5 subtypes in transfected COS-7 cells. This may be important in determining the regional specificity in neuronal aging and Alzheimer disease (AD). We assessed the effectiveness of blueberry (BB) and other high antioxidant (HA) fruit extracts (boysenberry, BY; cranberry, CB; black currant, BC; strawberry, SB; dried plums, DP; and grape, GR) on the toxic effects of Abeta 25-35 (100 microM, 24 hrs) and DA (1 mM, 4 hrs) on calcium buffering (Recovery) following oxotremorine (750 microM) -induced depolarization in M1AChR-transfected COS-7 cells, and on cell viability following DA (4 hrs) exposure. The extracts showed differential levels of Recovery protection in comparisons to the non-supplemented controls that was dependent upon whether DA or Abeta was used as the pretreatment. Interestingly, assessments of DA-induced decrements in viability revealed that all of the extracts had some protective effects. These findings suggest that the putative toxic effects of Abeta or DA might be reduced by HA fruit extracts.

Reversible dementia: a case of cryptococcal meningitis masquerading as Alzheimer's disease.

Abstract: A 70-year-old man presented to us in 1994 with a three-year history of worsening dementia. With the exceptions of a Mini-Mental State exam score of 20 and an inability to tandem walk, his physical and neurological examinations were normal. His past medical history revealed that in 1992 he had been evaluated at another institution for memory impairment and bifrontal headaches. A spinal tap had been done in 1992 showing elevated protein, reduced glucose, and a pleocytosis; his CSF fungal culture and cryptococcal antigen test were negative. He subsequently was lost to follow-up, and although his headaches had resolved, his mental status had continued to worsen. In 1994 his CSF cryptococcal antigen was positive, and his CSF fungal culture grew C. neoformans. He gradually improved with treatment for cryptococcal meningitis (CM). With the exception of mild memory impairment, in 2003 he and his family thought that his mental status had returned to normal. This case emphasizes that: 1) CM should always be kept in the differential diagnosis of dementia; 2) CM may be extremely insidious and difficult to diagnose; and 3) if one is to rule out unequivocally all possible reversible causes of dementia, one should perform a spinal tap.

Estrogen increases brain expression of the mRNA encoding transthyretin, an amyloid β scavenger protein

Abstract: Estrogen replacement therapy in postmenopausal women is associated with a reduced risk of Alzheimer's Disease (AD). The multiple mechanisms by which estrogen protects against AD are still unknown. To conduct a broad screen for estrogen-regulated AD-related genes in the brain, we used cDNA array assays of brain mRNA samples from ovariectomized (ovx) adult female mice treated with either 17beta-estradiol or vehicle at 1 or 5 weeks post-ovx. The gene encoding transthyretin (TTR), which has been reported to scavenge amyloid beta peptides and reduce amyloid plaque formation, is increased by estradiol treatment at both 1 and 5 weeks post-ovx. Northern blot analyses and RNase protection assays performed on whole brain samples obtained from estradiol- or vehicle-treated mice confirmed the cDNA array assays showing a significant increase in TTR mRNA with estradiol treatment. Qualitative in situ hybridization or immunocytochemistry performed on brain sections demonstrated that TTR mRNA is expressed only in choroid plexus and leptomeninges, and that both estrogen receptor proteins, alpha and beta, are present in choroid plexus cells. These novel findings suggest that estrogen may reduce the risk of AD by acting on choroid plexus cells to increase TTR gene expression, leading to enhanced sequestration and reduced aggregation of amyloid beta peptides.

Transferrin C2 variant does confer a risk for Alzheimer's disease in caucasians.

Abstract: Several gene mutations are associated with an increased risk of Alzheimer's disease. Previous studies reported higher transferrin C2 allele frequencies in Alzheimer's disease compared with normal controls. However, potential interactions between transferrin C2 and APOE (epsilon 4), have not been extensively investigated and have been the subject of controversial reports from several laboratories. We have carried out a case-control study on the association between Alzheimer's disease and transferrin C2 and APOE epsilon 4 alleles. epsilon 4 allele was associated with a four fold increase in the risk of disease, and transferrin C2 allele was significantly associated with Alzheimer's disease only in epsilon 4 negative subjects. These results suggest that apoE and transferrin may be part of a complex mechanism in the pathogenesis of Alzheimer's disease.

Apple juice prevents oxidative stress induced by amyloid-beta in culture

Abstract: Increased oxidative stress contributes to the decline in cognitive performance during normal aging and in neurodegenerative conditions such as Alzheimer's disease. Dietary supplementation with fruits and vegetables that are high in antioxidant potential have in some cases compensated for oxidative stress. Herein, we examined whether apple juice could alleviate the neurotoxic consequences of exposure of cultured neuronal cells to amyloid-beta (Abeta), since at least a portion of the neurotoxicity of Abeta is due to oxidative stress. Apple juice concentrate (AJC; 70 degree brix) was diluted into culture medium of SH-SY-5Y human neuroblastoma cells that had been differentiated for 7 days with 5 microM retinoic acid concurrent with the addition of 20 microM Abeta. AJC prevented the increased generation of reactive oxygen species (ROS) normally induced by Abeta treatment under these conditions. AJC also prevented Abeta-induced calcium influx and apoptosis, each of which results in part due to increased ROS. These findings suggest that the antioxidant potential of apple products can prevent Abeta-induced oxidative damage.

Increase of white matter string vessels in Alzheimer's disease.

Abstract: String vessels are collagenous structures connected to capillaries. They have no endothelial cells or lumen. We assessed collagen IV-labeled string vessels in the white matter (WM) of subjects with Alzheimer's disease (AD) (n = 12) and non-AD controls (n = 11) using 100 microm celloidin sections. Ten standard fields were digitally captured and the number and length of normal vessels and string vessels were quantified by computerized image analysis. The WM of the AD-diagnosed individuals contained more strings per mm2 (3.95 +/- 0.49) than comparable WM from controls (1.36 +/- 0.39) (p = 0.0005) and had increased total string vessel length in mm/mm2 (AD = 0.29 +/- 0.04; control = 0.10 +/- 0.03; p = 0.0015). There was a 25% increase (not statistically significant) in vessel density in mm/mm2 in AD subjects (AD = 11.88 +/- 0.87; control = 9.53 +/- 0.78; p = 0.06), presumably due to brain atrophy in the white matter. Although vessel length was slightly increased in AD subjects, they still had more than double the string length per total vessel length (AD = 2.88 +/- 0.38) compared to controls (1.36 +/- 0.27) (p = 0.0057). This increase in string vessels in the white matter of AD subjects suggests a decrease in vascular supply in this disease.

Thyrotropin releasing hormone inhibits tau phosphorylation by dual signaling pathways in hippocampal neurons

Abstract: Depletion of thyrotropin releasing hormone (TRH) gene expression resulted in augmented tau and glycosynthetase kinase-3beta (GSK-3beta), in contrast, TRH administration resulted in decreases of 75% in GSK-3beta and 90% in Tau phosphorylation in cultured rat hippocampal neurons. To further study TRH regulation of tau phosphorylation, immunoblotting was used to explore G-protein coupled TRH receptor activation of the phosphokinase C (PKC) and phosphokinase A (PKA) signaling pathways. TRH was found to rapidly activate PKA (2.5 fold in 10 min) while it suppressed PKC (levels decreased by 85% vs. control) in hippocampal neurons. This process was also discovered to be a cell type-specific response, as TRH activated PKC in only hypothalamic neurons. Further investigation revealed that the Src inhibitor Protein Phosphatase 2 (PP2, 50 uM) could block TRH inhibition of PKC, GSK-3beta, and tau phosphorylation with no effects on PKA. In addition, the PKC inhibitor GF109203 Bis (10 uM) was also able to suppress TRH inhibition of GSK-3beta, leading to increased GSK-3 beta activity. Independent of these effects, inhibition of PKA by H89 (10 uM) significantly blocked TRH inhibition of GSK-3 beta. These data suggests that both PKA and PKC are independently crucial to TRH's effects on GSK-3 beta, and support the roles of two distinct pathways involving suppression of PKC via the Src kinase and activation of PKA in mediating TRH effects on GSK-3 beta and tau. These dual signaling pathways between TRH and tau may provide mechanisms for the precise regulation of tau phosphorylation and dephosphorylation in neurons.

Interaction of Alzheimer's disease amyloid β peptide fragment 25-35 with tau protein, and with a tau peptide containing the microtubule binding domain

Abstract: The interaction of amyloid beta (Abeta) 25-35 with tau protein and with the peptide 1/2R (KVTSKCGSLGNIHHKPGGG), has been investigated by chromatography, electron microscopy, and surface plasmon resonance (SPR). Abeta 25-35 comprises the minimum region of Abeta peptide that is able to aggregate into fibrils, and 1/2R contains residues 307-325 from the tau region involved in microtubule binding. The results of chromatography showed that Abeta 25-35 induces the aggregation of tau protein and of tau peptide 1/2R. Likewise, the results of electron microscopy showed that Abeta 25-35 increases the tau peptide polymerization observed in the presence of polyanions like heparin. A decrease in Abeta 25-35 aggregation induced by tau peptide was also observed by both techniques. No direct interaction between tau protein immobilized on the sensor surface and Abeta 25-35 could be detected by SPR. However, incubation of tau protein at room temperature produced the loss of capability of this protein for interacting with the active biosensor surface. The presence of Abeta 25-35 during the incubation of tau protein makes more efficient this loss of interacting capability with the sensor surface. These results clearly indicate that Abeta 25-35, the peptide region to which the cytotoxic properties of Abeta can be assigned, interacts with the peptide region of tau protein involved in microtubule binding. This interaction produces the aggregation of tau peptide and the concomitant disassembling of Abeta 25-35, offering thus an explanation to the lack of co-localization of neurofibrillary tangles and senile plaques in Alzheimer's disease, and suggesting the possibility that tau protein may have a protective action by preventing Abeta from adopting the cytotoxic, aggregated form.

Oxidative stress and risk factors for Alzheimer's disease: clues to prevention and therapy.

Abstract: The protective role of antioxidants against the development of several diseases and conditions recognized as risk factors for Alzheimer's disease (AD) is discussed in the present work. A variety of health behaviors, including an adequate supply of antioxidant micronutrients with the diet might help preventing AD directly, or indirectly through the mitigation of pathologic conditions associated with AD, such as vascular disease and diabetes.