A comparison between radiometric and fluorimetric methods for measuring SSAO activity.

Semicarbazide-sensitive amine oxidase (SSAO) metabolizes the oxidative deamination of primary aromatic and aliphatic amines. The final cytotoxic products of its catalysis contribute to diseases involving vascular degeneration. The increasing interest in measuring SSAO activity has led to the development of several different methods. Herein, we compare SSAO activity results obtained with radiometric and fluorimetric methods in 49 plasma samples. Although not interchangeable, a significant correlation was obtained between methods. Considering these limitations, the fluorimetric method might replace the radioisotopic one.

Immunohistochemical study of semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 in the hippocampal vasculature: pathological synergy of Alzheimer's disease and diabetes mellitus.

Semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO/VAP-1) is involved in vascular endothelial damage as well as in the vascular degeneration underlying diabetes mellitus and Alzheimer's disease (AD). Recent evidence suggests that classic pathological features of AD are more pronounced in diabetic mellitus patients. To investigate the expression and distribution of SSAO/VAP-1 in the two pathologies, we have performed an immunohistochemical study in human hippocampal vessels of AD, AD with diabetic mellitus (ADD), diabetic mellitus (DM), and nondemented (ND) patients. The present results demonstrate major vessel accumulation of both SSAO/VAP-1 and amyloid-ß immunolabeling intensity in ADD compared with AD patients. Interestingly, nearly damaged vessels with high levels of SSAO/VAP-1 also showed increased oxidative damage markers (AGE, RAGE, and SOD-1) and glial activation (GFAP and HLA). Overall, this work suggests that high vascular SSAO/VAP-1 levels in human hippocampus may contribute to vascular degeneration, which can explain the severe progression in patients with both pathologies.

UTP affects the Schwannoma cell line proteome through P2Y receptors leading to cytoskeletal reorganisation.

Glial cells in the peripheral nervous system, such as Schwann cells, respond to nucleotides, which play an important role in axonal regeneration and myelination. Metabotropic P2Y receptor agonists are promising therapeutic molecules for peripheral neuropathies. Nevertheless, the proteomic mechanisms involved in nucleotide action on Schwann cells remain unknown. Here, we studied intracellular protein changes in RT4-D6P2T Schwann cells after treatment with nucleotides and Nucleo CMP Forte (CMPF), a nucleotide-based drug. After treatment with CMPF, 2-D DIGE revealed 11 differential gel spots, which were all upregulated. Among these, six different proteins were identified by MS. Some of these proteins are involved in actin remodelling (actin-related protein, Arp3), membrane vesicle transport (Rab GDP dissociation inhibitor ß, Rab GDI), and the endoplasmic reticulum stress response (protein disulfide isomerase A3, PDI), which are hallmarks of a possible P2Y receptor signalling pathway. Expression of P2Y receptors in RT4-D6P2T cells was demonstrated by RT-PCR and a transient elevation of intracellular calcium measured in response to UTP. Actin reorganisation was visualized after UTP treatment using phalloidin-FITC staining and was blocked by the P2Y antagonist suramin, which also inhibited Arp3, Rab GDI, and PDI protein upregulation. Our data indicate that extracellular UTP interacts with Schwann P2Y receptors and activates molecular machinery that induces changes in the glial cell cytoskeleton.

Is Ankyrin a genetic risk factor for psychiatric phenotypes?

BACKGROUND: Genome wide association studies reported two single nucleotide polymorphisms in ANK3 (rs9804190 and rs10994336) as independent genetic risk factors for bipolar disorder. Another SNP in ANK3 (rs10761482) was associated with schizophrenia in a large European sample. Within the debate on common susceptibility genes for schizophrenia and bipolar disorder, we tried to investigate common findings by analyzing association of ANK3 with schizophrenia, bipolar disorder and unipolar depression. METHODS: We genotyped three single nucleotide polymorphisms (SNPs) in ANK3 (rs9804190, rs10994336, and rs10761482) in a case-control sample of German descent including 920 patients with schizophrenia, 400 with bipolar affective disorder, 220 patients with unipolar depression according to ICD 10 and 480 healthy controls. Sample was further differentiated according to Leonhard's classification featuring disease entities with specific combination of bipolar and psychotic syndromes. RESULTS: We found no association of rs9804190 and rs10994336 with bipolar disorder, unipolar depression or schizophrenia. In contrast to previous findings rs10761482 was associated with bipolar disorder (p = 0.015) but not with schizophrenia or unipolar depression. We observed no association with disease entities according to Leonhard's classification. CONCLUSION: Our results support a specific genetic contribution of ANK3 to bipolar disorder though we failed to replicate findings for schizophrenia. We cannot confirm ANK3 as a common risk factor for different diseases.

The Δ4-desaturation pathway for DHA biosynthesis is operative in the human species: differences between normal controls and children with the Zellweger syndrome.

BACKGROUND: Docosahexaenoic acid (DHA, 22:6ω3) is a fundamental component of cell membranes, especially in the brain and retina. In the experimental animal, DHA deficiency leads to suboptimal neurological performance and visual deficiencies. Children with the Zellweger syndrome (ZS) have a profound DHA deficiency and symptoms that can be attributed to their extremely low DHA levels. These children seem to have a metabolic defect in DHA biosynthesis, which has never been totally elucidated. Treatment with DHA ethyl ester greatly improves these patients, but if we could normalize their endogenous DHA production we could get additional benefits. We examined whether DHA biosynthesis by Δ4-desaturation could be enhanced in the human species by transfecting the enzyme, and if this could normalize the DHA levels in cells from ZS patients. RESULTS: We showed that the Δ4-desaturase gene (Fad4) from Thraustochytrium sp, which can be expressed by heterologous transfection in other plant and yeast cells, can also be transfected into human lymphocytes, and that it expresses the enzyme (FAD4, Δ4-desaturase) by producing DHA from direct Δ4-desaturation of 22:5ω3. We also found that the other substrate for Δ4-desaturase, 22:4ω6, was parallely desaturated to 22:5ω6. CONCLUSIONS: The present "in vitro" study demonstrates that Δ4-desaturase can be transfected into human cells and synthesize DHA (as well as 22:5ω6, DPA) from 22:5ω3 and 22:4ω6, respectively, by putative Δ4-desaturation. Even if this pathway may not be the physiological route for DHA biosynthesis "in vivo", the present study opens new perspectives for the treatment of patients within the ZS spectrum.

Can enzyme kinetics of prooxidants teach us a lesson about the treatment of Alzheimer's disease: a pilot post-mortem study.

OBJECTIVES: Oxidative stress (OS), is defined as an imbalance of pro- and antioxidants, leading to increased production of free radicals, which can lead to cell damage and death, has been postulated as important factors in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). Most research has concentrated on the antioxidant system, for the first time, this proof of concept study examines the prooxidant system by investigating kinetic parameters of the free radical producing enzyme xanthine oxidase directly in post mortem brain tissue. METHODS: We determined the Michaelis-Menten constant (K(M)) and the maximal velocity (V(Max)) of xanthine oxidase (XO) in the cortico-limbic system of patients with AD using activity assays. RESULTS: We found the Michaelis-Menton constant of XO significantly decreased in hippocampus of patients with AD compared to controls. None of the other brain regions showed any significant alterations of these parameters. CONCLUSIONS: These results add further evidence to the amount of research indicating that OS plays an important role in AD. Moreover, these results should encourage more research in this field and it maybe speculated that this might open new avenues for treatment and prevention in AD.

Immunohistochemical analysis of human brain suggests pathological synergism of Alzheimer's disease and diabetes mellitus.

It has been extensively reported that diabetes mellitus (DM) patients have a higher risk of developing Alzheimer's disease (AD), but a mechanistic connection between both pathologies has not been provided so far. Carbohydrate-derived advanced glycation endproducts (AGEs) have been implicated in the chronic complications of DM and have been reported to play an important role in the pathogenesis of AD. The earliest histopathological manifestation of AD is the apparition of extracellular aggregates of the amyloid beta peptide (Abeta). To investigate possible correlations between AGEs and Abeta aggregates with both pathologies, we have performed an immuhistochemical study in human post-mortem samples of AD, AD with diabetes (ADD), diabetic and nondemented controls. ADD brains showed increased number of Abeta dense plaques and receptor for AGEs (RAGE)-positive and Tau-positive cells, higher AGEs levels and major microglial activation, compared to AD brain. Our results indicate that ADD patients present a significant increase of cell damage through a RAGE-dependent mechanism, suggesting that AGEs may promote the generation of an oxidative stress vicious cycle, which can explain the severe progression of patients with both pathologies.

Schizophrenia: from the brain to peripheral markers. A consensus paper of the WFSBP task force on biological markers.

Objective. The phenotypic complexity, together with the multifarious nature of the so-called "schizophrenic psychoses", limits our ability to form a simple and logical biologically based hypothesis for the disease group. Biological markers are defined as biochemical, physiological or anatomical traits that are specific to particular conditions. An important aim of biomarker discovery is the detection of disease correlates that can be used as diagnostic tools. Method. A selective review of the WFSBP Task Force on Biological Markers in schizophrenia is provided from the central nervous system to phenotypes, functional brain systems, chromosomal loci with potential genetic markers to the peripheral systems. Results. A number of biological measures have been proposed to be correlated with schizophrenia. At present, not a single biological trait in schizophrenia is available which achieves sufficient specificity, selectivity and is based on causal pathology and predictive validity to be recommended as diagnostic marker. Conclusions. With the emergence of new technologies and rigorous phenotypic subclassification the identification of genetic bases and assessment of dynamic disease related alterations will hopefully come to a new stage in the complex field of psychiatric research.

Oxidative stress in Alzheimer disease.

Alzheimer disease (AD) is a progressive dementia affecting a large proportion of the aging population. The histopathological changes in AD include neuronal cell death, formation of amyloid plaques and neurofibrillary tangles. There is also evidence that brain tissue in patients with AD is exposed to oxidative stress (e.g., protein oxidation, lipid oxidation, DNA oxidation and glycoxidation) during the course of the disease. Advanced glycation endproducts (AGEs) are present in amyloid plaques in AD, and its extracellular accumulation may be caused by an accelerated oxidation of glycated proteins. AGEs participate in neuronal death causing direct (chemical) and indirect (cellular) free radical production and consequently increase oxidative stress. The development of drugs for the treatment of AD that breaks the vicious cycles of oxidative stress and neurodegeneration offer new opportunities. These approaches include AGE-inhibitors, antioxidants and anti-inflammatory substances, which prevent free radical production.

Antimicrobial efficacy of 4.2% sodium hypochlorite adjusted to pH 12, 7.5, and 6.5 in infected human root canals.

OBJECTIVE: The purpose of this study was to determine the antimicrobial efficacy of sodium hypochlorite adjusted to pH 12, 7.5, and 6.5 in human root canals infected by Enterococcus faecalis. STUDY DESIGN: One hundred sixty-five human single-rooted teeth were prepared and inoculated with E. faecalis for 48 h. Teeth were divided into 3 experimental groups according to the irrigation pattern used: group 1, 4.2% NaOCl pH 12; group 2, 4.2% NaOCl pH 7.5; and group 3, 4.2% NaOCl pH 6.5. Samples from the root canals were collected, and bacterial growth was analyzed by turbidity of the culture medium. RESULTS: None of the irrigating solutions used in this study demonstrated 100% effectiveness against E. faecalis. The antibacterial effectiveness of 4.2% NaOCl at pH 6.5 was significantly increased (P = .03) compared with 4.2% NaOCl at pH 12 (chi-squared test: P < .05). CONCLUSION: Bactericidal activity of NaOCl solution is enhanced by weak acidification of 4.2% NaOCl solution at pH 6.5.

Sulfated polysaccharides promote the assembly of amyloid beta(1-42) peptide into stable fibrils of reduced cytotoxicity.

The histopathological hallmarks of Alzheimer disease are the self-aggregation of the amyloid beta peptide (Abeta) in extracellular amyloid fibrils and the formation of intraneuronal Tau filaments, but a convincing mechanism connecting both processes has yet to be provided. Here we show that the endogenous polysaccharide chondroitin sulfate B (CSB) promotes the formation of fibrillar structures of the 42-residue fragment, Abeta(1-42). Atomic force microscopy visualization, thioflavin T fluorescence, CD measurements, and cell viability assays indicate that CSB-induced fibrils are highly stable entities with abundant beta-sheet structure that have little toxicity for neuroblastoma cells. We propose a wedged cylinder model for Abeta(1-42) fibrils that is consistent with the majority of available data, it is an energetically favorable assembly that minimizes the exposure of hydrophobic areas, and it explains why fibrils do not grow in thickness. Fluorescence measurements of the effect of different Abeta(1-42) species on Ca(2+) homeostasis show that weakly structured nodular fibrils, but not CSB-induced smooth fibrils, trigger a rise in cytosolic Ca(2+) that depends on the presence of both extracellular and intracellular stocks. In vitro assays indicate that such transient, local Ca(2+) increases can have a direct effect in promoting the formation of Tau filaments similar to those isolated from Alzheimer disease brains.

Amyloidogenic properties of the prion protein fragment PrP(185-208): comparison with Alzheimer's peptide Abeta(1-28), influence of heparin and cell toxicity.

Amyloid fibrils are a hallmark of Alzheimer's and prion diseases. In both pathologies fibrils are found associated to glycosaminoglycans, modulators of the aggregation process. Amyloid peptides and proteins with very poor sequence homologies originate very similar aggregates. This implies the possible existence of a common formation mechanism. A homologous structural motif has recently been described for the Alzheimer's peptide Abeta(1-28) and the prion protein fragment PrP(185-208). We have studied the influence histidine residues and heparin on the aggregation process of both peptides and determined the possible amyloid characteristics of PrP(185-208), still unknown. The results show that PrP(185-208) forms amyloid aggregates in the presence of heparin. Histidines influence the aggregation kinetics, as in Abeta(1-28), although to a lesser extent. Other spectroscopic properties of the PrP(185-208) fragment are shown to be equivalent to those of other amyloid peptides and PrP(185-208) is shown to be cytotoxic using a neuroblastoma cell line.

CDP-choline reduces dopaminergic cell loss induced by MPP(+) and glutamate in primary mesencephalic cell culture.

Cytidine-5'-diphosphocholine (citicoline or CDP-choline) is an essential endogenous intermediate in the biosynthesis of phosphatidylcholine. In the present study, primary dopaminergic cultures from mouse mesencephala were treated with citicoline to investigate its neuroprotective potential on the survival of dopaminergic neurons exposed to MPP(+) and glutamate. Treatment with citicoline alone significantly increased the survival of dopaminergic neurons compared to controls. MPP(+) or glutamate decreased the total number of dopaminergic neurons whereas citicoline afforded significant protection against either toxicity. Moreover, citicoline significantly decreased propidium iodide uptake by cultured cells. The study concludes that citicoline exerts stimulant and neuroprotective actions on cultured dopaminergic neurons.

Fine structure study of Abeta1-42 fibrillogenesis with atomic force microscopy.

One of the hallmarks of Alzheimer's disease is the self-aggregation of the amyloid beta peptide (Abeta) in extracellular amyloid fibrils. Among the different forms of Abeta, the 42-residue fragment (Abeta1-42) readily self-associates and forms nucleation centers from where fibrils can quickly grow. The strong tendency of Abeta1-42 to aggregate is one of the reasons for the scarcity of data on its fibril formation process. We have used atomic force microscopy (AFM) to visualize in liquid environment the fibrillogenesis of synthetic Abeta1-42 on hydrophilic and hydrophobic surfaces. The results presented provide nanometric resolution of the main structures characteristic of the several steps from monomeric Abeta1-42 to mature fibrils in vitro. Oligomeric globular aggregates of Abeta1-42 precede the appearance of protofibrils, the first fibrillar species, although we have not obtained direct evidence of oligomer-protofibril interconversion. The protofibril dimensions deduced from our AFM images are consistent with a model that postulates the stacking of the peptide in a hairpin conformation perpendicular to the long axis of the protofibril, forming single beta-sheets ribbon-shaped. The most abundant form of Abeta1-42 fibril exhibits a nodular structure with a ~100-nm periodicity. This length is very similar 1) to the length of protofibril bundles that are the dominant feature at earlier stages in the aggregation process, 2) to the period of helical structures that have been observed in the core of fibrils, and 3) to the distance between regularly spaced, structurally weak fibril points. Taken together, these data are consistent with the existence of a ~100-nm long basic protofibril unit that is a key fibril building block.

Neurotrophic factors and the pathophysiology of schizophrenic psychoses.

The aim of this review is to summarize the present state of findings on altered neurotrophic factor levels in schizophrenic psychoses, on variations in genes coding for neurotrophic factors, and on the effect of antipsychotic drugs on the expression level of neurotrophic factors. This is a conceptual paper that aims to establish the link between the neuromaldevelopment theory of schizophrenia and neurotrophic factors. An extensive literature review has been done using the Pub Med database, a service of the National Library of Medicine, which includes over 14 million citations for biomedical articles back to the 1950s. The majority of studies discussed in this review support the notion of alterations of neurotrophic factors at the protein and gene level, respectively, and support the hypothesis that these alterations could, at least partially, explain some of the morphological, cytoarchitectural and neurobiochemical abnormalities found in the brain of schizophrenic patients. However, the results are not always conclusive and the clinical significance of these alterations is not fully understood. It is, thus, important to further neurotrophic factor research in order to better understand the etiopathogenesis of schizophrenic psychoses and, thus, potentially develop new treatment strategies urgently needed for patients suffering from these devastating disorders.

Up-regulation of striatal adenosine A(2A) receptors in schizophrenia.

Adenosine A (2A) receptors have been implicated in the pathophysiology of schizophrenia by clinical, anatomical, biochemical and genetic studies. We hypothesized that a genetically determined low number of adenosine A (2A) receptors could be a vulnerability factor for the development of the disease. The density of adenosine A (2A) receptors was investigated in human postmortem striatum of patients with schizophrenia (n = 9) and matched controls ( n= 9) using [ H)CGS 21680 as a radioligand probe. The maximum number of binding sites (B) (max) was 70% higher in patients with schizophrenia than in matched controls (609.4 +/- 259.1 354.0 +/- 156.4 fmol/mg protein, p=0.04). No significant difference could be discerned for the affinity of caffeine for adenosine A receptors between patients and controls. The increase in receptor density correlated with the dose of antipsychotic medication in chlorpromazine equivalents (r =0.61, = 0.014). We failed to provide evidence for a genetically determined reduction of adenosine A 2(A) receptors in schizophrenia. Instead, consistent with findings from animal experiments, our observation supports a role of adenosine A (2A) receptors in the molecular effects of antipsychotic drugs.

CDP-choline prevents glutamate-mediated cell death in cerebellar granule neurons.

Cytidine 5'-diphosphocholine (CDP-choline) has been shown to reduce neuronal degeneration induced in central nervous system (CNS) injury. However, the precise mechanism underlying the neuroprotective properties of this molecule is still unknown. Excitotoxicity causes cell death in CNS injury (trauma or ischemia) and has also been involved in neurodegenerative diseases. We have examined whether CDP-choline prevents glutamate-mediated cell death, determined by trypan blue exclusion and lactate dehydrogenase activity assays. Pretreatment of rat cerebellar granule cells (CGCs) with CDP-choline causes a dose- and time-dependent reduction of glutamate-induced excitotoxicity. Cell death is prevented >50% when 100 microM CDP-choline is added 6 d before the glutamate excitotoxic insult but less than 20% when added concomitantly with glutamate. Pretreatment of CGCs with CDP-choline reduces almost completely (>80%) the number of apoptotic cells analyzed by flow cytometry, suggesting that CDP-choline exerts a neuroprotective effect by inhibiting the apoptotic pathway induced by glutamate.