concanavalin-a and Alzheimer-Disease

A number of biomarkers (e.g. Abeta, tau) has been identified in Alzheimer's disease CSF. However, none fulfils the criteria of sensitivity and specificity (> 80%) needed for the development of an accurate diagnostic test. The lack of a suitable marker has prompted the search for new CSF biomarkers. In this study, the glycosylation of CSF proteins was examined using lectin blotting. Lumbar CSF was collected ante mortem from 22 non-Alzheimer's disease and 12 probable Alzheimer's disease cases and ventricular CSF collected post mortem from 7 non-Alzheimer's disease and 16 Alzheimer's disease cases confirmed by pathologic examination. When CSF glycoproteins were stained with wheat germ agglutinin (WGA), the staining intensity was found to be significantly lower in the Alzheimer's disease group. No difference in staining was found using other lectins (Canavalia ensiformis agglutinin, Ricinus communis agglutinin, Lens culinaris agglutinin). The measurement of WGA-reactive glycoproteins in CSF may be a useful biomarker for diagnosis of Alzheimer's disease.

Topics: Aged; Alzheimer Disease; Biomarkers; Coloring Agents; Concanavalin A; Female; Glycosylation; Humans; Lectins; Male; Molecular Weight; Plant Lectins; Wheat Germ Agglutinins

Alzheimer's disease (AD) seriously threatens patients' lives and causes severe burden to the families. Early prevention and treatment can alleviate the development of the disease; therefore it is important to find new effective and non-traumatic biomarkers for early diagnosis. In this study, peripheral blood samples were collected from 24 AD patients and the same number of age- and gender-matched control subjects. Lectin reactive glycosylation levels including beta-D-galactosyl ricinus communis agglutinin 120 (RCA), peanut agglutinin (PNA), concanavalin agglutinin (Con A), alpha-L-fucosyl ulex europeus agglutinin (UEA), dolichos biflorus agglutinin (DBA), and galanthus nivalis (GNL), in the red blood cells of peripheral blood were examined by western blotting. We found that lectin levels were altered with aging and gender; some lectin levels were different between AD patients and the control subjects. Only Con A levels were significantly decreased in AD patients compared to age-matched control subjects. These results suggest that Con A levels in peripheral blood may be a potent diagnostic marker for AD.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Biomarkers; Case-Control Studies; Concanavalin A; Female; Humans; Lectins; Male; Plant Lectins

Alzheimer's disease (AD) is the most common type of dementia, comprising 60-80% of all reported cases, and currently affects 5.2 million Americans. AD is characterized pathologically by the accumulation of senile plaques (SPs), neurofibrillary tangles (NFTs), and synapse loss. The early stages of memory loss associated with AD have been studied in a condition known as amnestic mild cognitive impairment (MCI), arguably the earliest form of AD. In spite of extensive research across a variety of disciplines, the cause of AD remains elusive. Proteomics techniques have helped to advance knowledge about AD by identifying irregularities in protein expression and post-translational modifications (PTMs) in AD brain. Glycosylation is a less studied PTM with regards to AD and MCI. This PTM is important to study because glycosylation is involved in proper protein folding, protein anchoring to cell membranes, and the delivery of proteins to organelles, and these processes are impaired in AD. Concanavalin-A (Con-A) binds to N-linked glycoproteins, but hydrophobic sites on nonglycoproteins are also known to bind Con-A. To our knowledge, the present study is the first to examine Con-A-associated brain proteins in MCI and AD with focus on the hippocampus and inferior parietal lobule (IPL) brain regions. Proteins found in AD hippocampus with altered levels are glutamate dehydrogenase (GDH), glial fibrillary acidic protein (GFAP), tropomyosin 3 (TPM3), Rab GDP-dissociation inhibitor XAP-4 (XAP4), and heat shock protein 90 (HSP90). Proteins found with altered levels in AD IPL are alpha-enolase, gamma-enolase, and XAP-4. MCI hippocampal proteins with altered levels are dihydropyrimidase-2 (DRP2), glucose-regulated protein 78 (GRP-78), protein phosphatase related protein Sds-22 (Sds22), and GFAP and the only protein found with altered levels in MCI IPL was beta-synuclein. These results are discussed with reference to biochemical and pathological alterations in and progression of AD.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Chromatography, Affinity; Cognition Disorders; Concanavalin A; Disease Progression; Female; Hippocampus; Humans; Male; Molecular Sequence Data; Parietal Lobe; Proteome; Proteomics

The modulation of recombinant NMDA receptors by conantokin-G (con-G) and Ala7-conantokin-G (Ala7-Con-G) was investigated in Xenopus oocytes injected with capped RNA coding for NR1 splice variants and NR2 subunits using the two-electrode voltage clamp technique. Glutamate exhibited a marginally higher apparent affinity for NR2A-containing receptors than NR2B-containing receptors, regardless of the NR1 subunit present. Conantokins were bath applied to give cumulative concentration responses in the presence of 3 and 30 mum glutamate. Both contantokins exhibited biphasic concentration-response relationships at NR2A-containing NMDA receptors, producing potentiation at low conantokin concentrations and inhibition at high concentrations. These effects were stronger with glutamate concentrations near its EC50, and less marked at saturating concentrations. In contrast, the conantokin concentration-response relation was monophasic and inhibitory at NR2B-containing receptors. We conclude that the combinations of subunits that comprise the NMDA receptor complex influence conantokin and glutamate affinities and the nature of the responses to conantokins.

Topics: Alanine; Alzheimer Disease; Animals; Concanavalin A; Conotoxins; Electrophysiology; Excitatory Amino Acid Antagonists; Glutamic Acid; Humans; Membrane Potentials; Oocytes; Patch-Clamp Techniques; Receptors, N-Methyl-D-Aspartate; Recombinant Proteins; Xenopus

Cytokines appear to be involved in the pathogenesis of Alzheimer's Disease (AD). Their modulation by treatment has been investigated only in a few studies. The aim of our study was to evaluate the effect of acetylcholinesterase inhibitors (AChEI) on Interleukin-4 (IL-4) production in AD patients. IL-4 levels were measured by ELISA on peripheral blood mononuclear cell cultures in the presence or absence of Concanavalin A or Phytohaemagglutinin. Linear regression analysis shows that patients who have been treated, have higher levels of IL-4 independently from age, gender and comorbidity. The increased production of IL-4 in AChEI treated patients might represent an additional mechanism through which AChEI act on AD progression.

Topics: Aged; Alzheimer Disease; Cells, Cultured; Cholinesterase Inhibitors; Concanavalin A; Female; Humans; Interleukin-4; Male; Nootropic Agents; Phytohemagglutinins; Up-Regulation

Caspases mediate essential key proteolytic events in inflammatory cascades and the apoptotic cell death pathway. Human caspases functionally segregate into two distinct subfamilies: those involved in cytokine maturation (caspase-1, -4 and -5) and those involved in cellular apoptosis (caspase-2, -3, -6, -7, -8, -9 and -10). Although caspase-12 is phylogenetically related to the cytokine maturation caspases, in mice it has been proposed as a mediator of apoptosis induced by endoplasmic reticulum stress including amyloid-beta cytotoxicity, suggesting that it might contribute to the pathogenesis of Alzheimer's disease. Here we show that a single nucleotide polymorphism in caspase-12 in humans results in the synthesis of either a truncated protein (Csp12-S) or a full-length caspase proenzyme (Csp12-L). The read-through single nucleotide polymorphism encoding Csp12-L is confined to populations of African descent and confers hypo-responsiveness to lipopolysaccharide-stimulated cytokine production in ex vivo whole blood, but has no significant effect on apoptotic sensitivity. In a preliminary study, we find that the frequency of the Csp12-L allele is increased in African American individuals with severe sepsis. Thus, Csp12-L attenuates the inflammatory and innate immune response to endotoxins and in doing so may constitute a risk factor for developing sepsis.

Topics: Africa; Alzheimer Disease; Animals; Apoptosis; Base Sequence; Black or African American; Case-Control Studies; Caspase 12; Caspases; Concanavalin A; Cytokines; Endoplasmic Reticulum; Gene Frequency; Genetic Predisposition to Disease; Genotype; Humans; Inflammation; Lipopolysaccharides; NF-kappa B; Polymorphism, Single Nucleotide; Primates; Sepsis

A proteomic approach was employed to elucidate possible differential expression of native and oxidized glycoproteins using pooled plasma samples derived from ten patients with sporadic Alzheimer's disease (AD) and pooled plasma samples from nine normal elderly control (NEC) subjects. The plasma samples were fractionated by sequential affinity chromatography on heparin-agarose (HepA) and concanavalin A-agarose (ConA) columns followed by separation on one-dimensional and two-dimensional polyacrylamide gels. Carbonylation (oxidation) of proteins was monitored by in-strip derivatization with 2,4-dinitrophenylhydrazine (DNP) and anti-DNP immunoblotting. Nine spots representing glycoproteins which showed enrichment or high specific oxidation indices in AD HepA-ConA 2-D gels relative to NEC samples were analyzed by matrix-assisted laser desorption-time of flight-mass spectrometry and identified with high probability (p < 0.001) as isoforms of human transferrin (Tf), hemopexin (Hpx) and alpha-1-antitrypsin (alpha-1-AT). These glycoproteins were concentrated, respectively, 5-, 6.5- and 107-fold in HepA-ConA eluates derived from AD plasma relative to the NEC samples. Specific oxidation indices of the identified Tf and Hpx isoforms in AD plasma were respectively, 7.4 and 2.8 relative to NEC. Our findings provide further evidence for systemic derangements in heme/iron/redox homeostasis and activation of the acute phase response in sporadic AD. Moreover, the data implicate isoforms of Tf, Hpx and alpha-1-AT as potential biological markers of this condition.

Topics: alpha 1-Antitrypsin; Alzheimer Disease; Chromatography, Affinity; Concanavalin A; Electrophoresis, Gel, Two-Dimensional; Glycoproteins; Hemopexin; Heparin; Humans; Oxidation-Reduction; Phenylhydrazines; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Transferrin

Recent studies demonstrate diminished calcium uptake by cultured skin fibroblasts from Alzheimer patients. To determine if altered calcium homeostasis is also present in tissue taken from Alzheimer patients, calcium homeostasis was assessed in mitogen-stimulated lymphocytes. Calcium uptake by lymphocytes from Alzheimer patients was 10%-15% lower (p less than 0.002) than that of lymphocytes from age-matched controls. However, neither superficially bound nor total calcium was altered by Alzheimer's disease. These small differences in uptake may reflect larger differences in cytosolic calcium, in later calcium-mediated events, or in the response of particular subsets of lymphocytes. Their biological significance remains to be determined.

Topics: Aged; Alzheimer Disease; Calcium; Concanavalin A; Female; Homeostasis; Humans; In Vitro Techniques; Leukocytes; Male

T-lymphocyte function in Alzheimer's disease (AS) was evaluated by means of delayed type hypersensitivity (DTH) and mitogen responsiveness using concanavalin A (Con A) and BCG vaccine as stimulators. DTH and the response to Con A was significantly lower in AD than in normal aging. The Con A response included one group in which the thymidine uptake was lower than the minimum normal response while another group was within the normal range. This subset could account for the inconsistency in previous reports of T-cell function in AD.

Topics: Alzheimer Disease; BCG Vaccine; Concanavalin A; Humans; Immunity, Cellular; Lymphocyte Activation; T-Lymphocytes