A Cyclic Peptide Mimic of the ß-Amyloid Binding Domain on Transthyretin.

Self-association of ß-amyloid (Aß) into oligomers and fibrils is associated with Alzheimer's disease (AD), motivating the search for compounds that bind to and inhibit Aß oligomerization and/or neurotoxicity. Peptides are an attractive class of such compounds, with potential advantages over small molecules in affinity and specificity. Self-complementation and peptide library screening are two strategies that have been employed in the search for peptides that bind to Aß. Alternatively, one could design Aß-binding peptides based on knowledge of complementary binding proteins. One candidate protein, transthyretin (TTR), binds Aß, inhibits aggregation, and reduces its toxicity. Previously, strand G of TTR was identified as part of a specific Aß binding domain, and G16, a 16-mer peptide with a sequence that spans strands G and H of TTR, was synthesized and tested. Although both TTR and G16 bound to Aß, they differed significantly in their effect on Aß aggregation, and G16 was less effective than TTR at protecting neurons from Aß toxicity. G16 lacks the ß-strand/loop/ß-strand structure of TTR's Aß binding domain. To enforce proper residue alignment, we transplanted the G16 sequence onto a ß-hairpin template. Two peptides with 18 and 22 amino acids were synthesized using an orthogonally protected glutamic acid derivative, and an N-to-C cyclization reaction was carried out to further restrict conformational flexibility. The cyclized 22-mer (but not the noncyclized 22-mer nor the 18-mer) strongly suppressed Aß aggregation into fibrils, and protected neurons against Aß toxicity. The imposition of structural constraints generated a much-improved peptidomimetic of the Aß binding epitope on TTR.

Increased Alzheimer's disease-like pathology in the APP/ PS1ΔE9 mouse model lacking Nrf2 through modulation of autophagy.

The presence of senile plaques is one of the major pathologic hallmarks of the brain with Alzheimer's disease (AD). The plaques predominantly contain insoluble amyloid ß-peptide, a cleavage product of the larger amyloid precursor protein (APP). Two enzymes, named ß and γ secretase, generate the neurotoxic amyloid-ß peptide from APP. Mature APP is also turned over endogenously by autophagy, more specifically by the endosomal-lysosomal pathway. A defective lysosomal system is known to be pathogenic in AD. Modulation of NF-E2 related factor 2 (Nrf2) has been shown in several neurodegenerative disorders, and Nrf2 has become a potential therapeutic target for various neurodegenerative disorders, including AD, Parkinson's disease, and amyotrophic lateral sclerosis. In the current study, we explored the effect of genetic ablation of Nrf2 on APP/Aß processing and/or aggregation as well as changes in autophagic dysfunction in APP/PS1 mice. There was a significant increase in inflammatory response in APP/PS1 mice lacking Nrf2. This was accompanied by increased intracellular levels of APP, Aß (1-42), and Aß (1-40), without a change total full-length APP. There was a shift of APP and Aß into the insoluble fraction, as well as increased poly-ubiquitin conjugated proteins in mice lacking Nrf2. APP/PS1-mediated autophagic dysfunction is also enhanced in Nrf2-deficient mice. Finally, neurons in the APP/PS1/Nrf2-/- mice had increased accumulation of multivesicular bodies, endosomes, and lysosomes. These outcomes provide a better understanding of the role of Nrf2 in modulating autophagy in an AD mouse model and may help design better Nrf2 targeted therapeutics that could be efficacious in the treatment of AD.

Transthyretin-derived peptides as ß-amyloid inhibitors.

Self-association of ß-amyloid (Aß) into soluble oligomers and fibrillar aggregates is associated with Alzheimer's disease pathology, motivating the search for compounds that selectively bind to and inhibit Aß oligomerization and/or neurotoxicity. Numerous small-molecule inhibitors of Aß aggregation or toxicity have been reported in the literature. However, because of their greater size and complexity, peptides and peptidomimetics may afford improved specificity and affinity as Aß aggregation modulators compared to small molecules. Two divergent strategies have been employed in the search for peptides that bind Aß: (i) using recognition domains corresponding to sequences in Aß itself (such as KLVFF) and (ii) screening random peptide-based libraries. In this study, we propose a third strategy, specifically, designing peptides that mimic binding domains of Aß-binding proteins. Transthyretin, a plasma transport protein that is also relatively abundant in cerebrospinal fluid, has been shown to bind to Aß, inhibit aggregation, and reduce its toxicity. Previously, we identified strand G of transthyretin as a specific Aß binding domain. In this work we further explore and define the necessary features of this binding domain. We demonstrate that peptides derived from transthyretin bind Aß and inhibit its toxicity. We also show that, although both transthyretin and transthyretin-derived peptides bind Aß and inhibit toxicity, they differ significantly in their effect on Aß aggregation.

Characterization of a fluorescent probe for imaging nitric oxide.

BACKGROUND: Nitric oxide (NO), a potent vasodilator and anti-atherogenic molecule, is synthesized in various cell types, including vascular endothelial cells (ECs). The biological importance of NO enforces the need to develop and characterize specific and sensitive probes. To date, several fluorophores, chromophores and colorimetric techniques have been developed to detect NO or its metabolites (NO(2) and NO(3)) in biological fluids, viable cells or cell lysates. METHODS: Recently, a novel probe (NO(550)) has been developed and reported to detect NO in solutions and in primary astrocytes and neuronal cells with a fluorescence signal arising from a nonfluorescent background. RESULTS: Here, we report further characterization of this probe by optimizing conditions for the detection and imaging of NO products in primary vascular ECs, fibroblasts, and embryonic stem cell- and induced pluripotent stem cell-derived ECs in the absence and presence of pharmacological agents that modulate NO levels. In addition, we studied the stability of this probe in cells over time and evaluated its compartmentalization in reference to organelle-labeling dyes. Finally, we synthesized an inherently fluorescent diazo ring compound (AZO(550)) that is expected to form when the nonfluorescent NO(550) reacts with cellular NO, and compared its cellular distribution with that of NO(550). CONCLUSION: NO(550) is a promising agent for imaging NO at baseline and in response to pharmacological agents that modulate its levels.

Chiral suprastructures of asymmetric oligothiophene-hybrids induced by a single proline.

Oligothiophene-proline hybrids were synthesized via click-reaction showing intriguing self-assembly behavior in an aqueous environment by forming chiral superstructures, whose helicity is controlled by the configuration of the amino acid moiety.

Comparative study of extended versus short term thromboprophylaxis in patients undergoing elective total hip and knee arthroplasty in Indian population.

BACKGROUND: Postoperative thromboprophylaxis with low molecular weight heparin (LMWH) for an extended period of 4 weeks is now preferred over short term thromboprophylaxis in patients undergoing total hip/knee arthroplasty (THA/TKA). However, most of the data demonstrating the efficacy and safety of extended thromboprophylaxis and short term thromboprophylaxis is from clinical trials done in the West. In India, the data of the incidence of venous thromboembolism (VTE) following THA/TKA has been conflicting and the duration has not been clearly defined. The aim of the study was to evaluate and compare the efficacy of extended thromboprophylaxis over short term thromboprophylaxis in Indian patients undergoing elective THA/TKA surgeries. MATERIALS AND METHODS: A prospective arm of 197 consecutive patients undergoing elective THA/TKA surgeries who were administered extended thromboprophylaxis for 4 weeks was compared with a historical group of 795 patients who were administered short term thromboprophylaxis for only 7-11 days. In both groups, LMWH (enoxaparin) was used in a dose of 40 mg subcutaneously, in addition to mechanical thromboprophylaxis. Primary efficacy endpoint was objectively confirmed venous thromboembolism (VTE). The presence of DVT was confirmed by a combination of pretest scoring, D-dimer, and Color Doppler Flow Imaging (CDFI) of deep veins of the legs, and pulmonary thromboembolism (PTE) was confirmed by ventilation perfusion (V/Q) scan or pulmonary angiography. Fisher's exact test and t test were used for the statistical analysis. The baseline confounding factors were compared between the two groups using t test for comparing the means for continuous data and Fisher's exact test for categorical data. RESULTS: In the prospective arm, only 1 patient developed symptomatic PTE compared to 26 (3.27%) cases of VTE (20 cases of PTE and 6 cases of DVT) in the retrospective group. CONCLUSION: Extended thromboprophylaxis (for 4 weeks) was found to be more effective than short term thromboprophylaxis in minimizing the risk of postoperative VTE in patients who underwent THA/TKA.

Transthyretin as both a sensor and a scavenger of ß-amyloid oligomers.

Transthyretin (TTR) is a homotetrameric transport protein, assembled from monomers that each contain two four-stranded ß-sheets and a short α-helix and loop. In the tetramer, the "inner" ß-sheet forms a hydrophobic pocket while the helix and loop are solvent-exposed. ß-Amyloid (Aß) aggregates bind to TTR, and the level of binding is significantly reduced in mutants L82A (on the loop) and L110A (on the inner ß-sheet). Protection against Aß toxicity was demonstrated for wild-type TTR but not L82A or L110A, providing a direct link between TTR-Aß binding and TTR-mediated cytoprotection. Protection is afforded at substoichiometric (1:100) TTR:Aß molar ratios, and the level of binding of Aß to TTR is highest for partially aggregated materials and decreased for freshly prepared or heavily aggregated Aß, suggesting that TTR binds selectively to soluble toxic Aß aggregates. A novel technique, nanoparticle tracking, is used to show that TTR arrests Aß aggregation by both preventing formation of new aggregates and inhibiting growth of existing aggregates. TTR tetramers are normally quite stable; tetrameric structure is necessary for the protein's transport functions, and mutations that decrease tetramer stability have been linked to TTR amyloid diseases. However, TTR monomers bind more Aß than do tetramers, presumably because the hydrophobic inner sheet is solvent-exposed upon tetramer disassembly. Wild-type and L110A tetramers, but not L82A, were destabilized upon being co-incubated with Aß, suggesting that binding of Aß to L82 triggers tetramer dissociation. Taken together, these results suggest a novel mechanism of action for TTR: the EF helix/loop "senses" the presence of soluble toxic Aß oligomers, triggering destabilization of TTR tetramers and exposure of the hydrophobic inner sheet, which then "scavenges" these toxic oligomers and prevents them from causing cell death.

Dynamic thiol exchange with ß-sulfido-α,ß-unsaturated carbonyl compounds and dithianes.

A reversible covalent bond exchange of thiols, ß-sulfido-α,ß-unsaturated carbonyls, and dithianes has been studied in DMSO and D(2)O/DMSO mixtures. The equilibrium between thiols and ß-sulfido-α,ß-unsaturated carbonyls is obtained within a few hours, while the equilibration starting with the ß-dithiane carbonyls and thiols requires a few days. This time scale makes the system ideal for utilization in dynamic combinatorial chemistry.

Discovery of potent, novel Nrf2 inducers via quantum modeling, virtual screening, and in vitro experimental validation.

Nuclear factor erythroid 2-related factor 2 (Nrf2) is the master transcription factor of the antioxidant response element pathway, coordinating the induction of detoxifying and antioxidant enzymes. Nrf2 is normally sequestered in the cytoplasm by Kelch-like ECH-associating protein 1 (Keap1). To identify novel small molecules that will disturb Nrf2-Keap1 binding and promote activation of the Nrf2- antioxidant response element pathway, we generated a quantum model based on the structures of known Nrf2- antioxidant response element activators. We used the quantum model to perform in silico screening on over 18 million commercially available chemicals to identify the structures predicted to activate the Nrf2- antioxidant response element pathway based on the quantum model. The top hits were tested in vitro, and half of the predicted hits activated the Nrf2-antioxidant response element pathway significantly in primary cell culture. In addition, we identified a new family of Nrf2-antioxidant response element-activating structures that all have comparable activity to tBHQ and protect against oxidative stress and dopaminergic toxins in vitro. The improved ability to identify potent activators of Nrf2 through the combination of in silico and in vitro screening described here improves the speed and cost associated with screening Nrf2-antioxidant response element -activating compounds for drug development.

The Nrf2-ARE pathway: a valuable therapeutic target for the treatment of neurodegenerative diseases.

Modulation of NF-E2 related factor 2 (Nrf2) has been shown in several neurodegenerative disorders. The overexpression of Nrf2 has become a potential therapeutic avenue for various neurodegenerative disorders such as Parkinson, Amyotrophic lateral sclerosis, and Alzheimer's disease. The expression of phase II detoxification enzymes is governed by the cis-acting regulatory element known as antioxidant response element (ARE). The transcription factor Nrf2 binds to ARE thereby transcribing multitude of antioxidant genes. Keap1, a culin 3-based E3 ligase that targets Nrf2 for degradation, sequesters Nrf2 in cytoplasm. Disruption of Keap1-Nrf2 interaction or genetic overexpression of Nrf2 can increase the endogenous antioxidant capacity of the brain thereby rendering protection against oxidative stress in neurodegenerative disorders. This review primarily focuses on recent patents that target Nrf2 overexpression as a promising therapeutic strategy for the treatment of neurodegenerative disorders.

New H-bonding patterns in biphenyl-based synthetic lectins; pyrrolediamine bridges enhance glucose-selectivity.

Synthetic lectins are molecules designed for the challenging task of biomimetic carbohydrate recognition in water. Previous work has explored a family of such systems based on bi/terphenyl units as hydrophobic surfaces and isophthalamide spacers to provide polar binding groups. Here we report a related receptor which employs a new spacer, 2,5-bis-(aminomethyl)-pyrrole, with an alternative (A-D-A) set of H-bonding valencies. The modified spacer leads to significant changes in binding selectivity, including a preference for glucose over all other tested substrates.

Proteomic analysis of brain proteins in APP/PS-1 human double mutant knock-in mice with increasing amyloid ß-peptide deposition: insights into the effects of in vivo treatment with N-acetylcysteine as a potential therapeutic intervention in mild cognitive impairment and Alzheimer's disease.

Proteomics analyses were performed on the brains of wild-type (WT) controls and an Alzheimer's disease (AD) mouse model, APP/PS-1 human double mutant knock-in mice. Mice were given either drinking water or water supplemented with N-acetylcysteine (NAC) (2 mg/kg body weight) for a period of five months. The time periods of treatment correspond to ages prior to Aß deposition (i.e. 4-9 months), resembling human mild cognitive impairment (MCI), and after Aß deposition (i.e. 7-12 months), more closely resembling advancing stages of AD. Substantial differences exist between the proteomes of WT and APP/PS-1 mice at 9 or 12 months, indicating that Aß deposition and oxidative stress lead to downstream changes in protein expression. Altered proteins are involved in energy-related pathways, excitotoxicity, cell cycle signaling, synaptic abnormalities, and cellular defense and structure. Overall, the proteomic results support the notion that NAC may be beneficial for increasing cellular stress responses in WT mice and for influencing the levels of energy- and mitochondria-related proteins in APP/PS-1 mice.

Molecular recognition of ß-O-GlcNAc glycopeptides by a lectin-like receptor: binding modulation by the underlying Ser or Thr amino acids.

The binding properties of different carbohydrates and glycopeptides containing the ß-O-2-deoxy-2-(N-acetyl)-D-glucosaminyl (ß-O-GlcNAc) to a synthetically prepared lectin-like receptor have been analyzed. The study combines the use of NMR spectroscopy experiments with extensive MD simulations in explicit water. Notably, the presence of a key hydrogen bond between the receptor and the OMe group of the ß-O-GlcNAc-OMe derivative appears to be responsible for the high selectivity observed for this compound. In addition, to study the effect on the binding of the underlying amino acid, we have prepared different model glycopeptides, which include the non-natural α-methylserine and α-methylthreonine as underlying amino acids. Interestingly, the presence of a methyl group decreases the affinity constant, especially in those cases in which a ß-methyl group is present. As a result, the serine-containing glycopeptide exhibited the highest affinity constant of the glycopeptides, and the threonine derivative showed the lowest one. This low selectivity could have its origin in the difficulty to form both specific hydrogen bonds and hydrophobic (CH-π) contacts.

Potential in vivo amelioration by N-acetyl-L-cysteine of oxidative stress in brain in human double mutant APP/PS-1 knock-in mice: toward therapeutic modulation of mild cognitive impairment.

Alzheimer's disease (AD) is the most prevalent form of dementia among the elderly. Although the underlying cause has yet to be established, numerous data have shown that oxidative stress is implicated in AD as well as in preclinical stages of AD, such as mild cognitive impairment (MCI). The oxidative stress observed in brains of subjects with AD and MCI may be due, either fully or in part, to increased free radicals mediated by amyloid-beta peptide (Abeta). By using double human mutant APP/PS-1 knock-in mice as the AD model, the present work demonstrates that the APP/PS-1 double mutation results in elevated protein oxidation (as indexed by protein carbonyls), protein nitration (as indexed by 3-nitrotyrosine), as well as lipid peroxidation (as indexed by protein-bound 4-hydroxy-2-nonenal) in brains of mice aged 9 months and 12 months. APP/PS-1 mice also exhibited lower levels of brain glutathione peroxidase (GPx) in both age groups studied, whereas glutathione reductase (GR) levels in brain were unaffected by the mutation. The activities of both of these antioxidant enzymes were significantly decreased in APP/PS-1 mouse brains, whereas the activity of glucose-6-phosphate dehydrogenase (G6PDH) was increased relative to controls in both age groups. Levels of peptidyl prolyl isomerase 1 (Pin1) were significantly decreased in APP/PS-1 mouse brain aged 9 and 12 months. Administration of N-acetyl-L-cysteine (NAC), a glutathione precursor, to APP/PS-1 mice via drinking water suppressed increased protein oxidation and nitration and also significantly augmented levels and activity of GPx in brain from both age groups. Oral administration of NAC also increased the diminished activity of GR and protected against lipid peroxidation in brains of 9-month-old APP/PS-1 mice only. Pin1 levels, GR levels, and G6PDH activity in brain were unaffected by oral administration of NAC in both age groups. These results are discussed with reference to the therapeutic potential of this brain-accessible glutathione precursor in the treatment of MCI and AD.

Progress in biomimetic carbohydrate recognition.

The importance of carbohydrate recognition in biology, and the unusual challenges involved, have lead to great interest in mimicking saccharide-binding proteins such as lectins. In this review, we discuss the design of artificial carbohydrate receptors, focusing on those which work under natural (i.e. aqueous) conditions. The problem is intrinsically difficult because of the similarity between substrate (carbohydrate) and solvent (water) and, accordingly, progress has been slow. However, recent developments suggest that solutions can be found. In particular, the "temple" family of carbohydrate receptors show good affinities and excellent selectivities for certain all-equatorial substrates. One example is selective for O-linked beta-N-acetylglucosamine (GlcNAc, as in the O-GlcNAc protein modification), while another is specific for beta-cellobiosyl and closely related disaccharides. Both show roughly millimolar affinities, matching the strength of some lectin-carbohydrate interactions.

Protective effect of quercetin in primary neurons against Abeta(1-42): relevance to Alzheimer's disease.

Quercetin, a flavonoid found in various foodstuffs, has antioxidant properties and increases glutathione (GSH) levels and antioxidant enzyme function. Considerable attention has been focused on increasing the intracellular GSH levels in many diseases, including Alzheimer's disease (AD). Amyloid beta-peptide [Abeta(1-42)], elevated in AD brain, is associated with oxidative stress and neurotoxicity. We aimed to investigate the protective effects of quercetin on Abeta(1-42)-induced oxidative cell toxicity in cultured neurons in the present study. Decreased cell survival in neuronal cultures treated with Abeta(1-42) correlated with increased free radical production measured by dichlorofluorescein fluorescence and an increase in protein oxidation (protein carbonyl, 3-nitrotyrosine) and lipid peroxidation (protein-bound 4-hydroxy-2-nonenal). Pretreatment of primary hippocampal cultures with quercetin significantly attenuated Abeta(1-42)-induced cytotoxicity, protein oxidation, lipid peroxidation and apoptosis. A dose-response study suggested that quercetin showed protective effects against Abeta(1-42) toxicity by modulating oxidative stress at lower doses, but higher doses were not only non-neuroprotective but also toxic. These findings provide motivation to test the hypothesis that quercetin may provide a promising approach for the treatment of AD and other oxidative-stress-related neurodegenerative diseases.

Proteomic identification of brain proteins in the canine model of human aging following a long-term treatment with antioxidants and a program of behavioral enrichment: relevance to Alzheimer's disease.

Aging and age-related disorders such as Alzheimer's disease (AD) are usually accompanied by oxidative stress as one of the main mechanisms contributing to neurodegeneration and cognitive decline. Aging canines develop cognitive dysfunction and neuropathology similar to those seen in humans, and the use of antioxidants results in reductions in oxidative damage and in improvement in cognitive function in this canine model of human aging. In the present study, the effect of a long-term treatment with an antioxidant-fortified diet and a program of behavioral enrichment on oxidative damage was studied in aged canines. To identify the neurobiological mechanisms underlying these treatment effects, the parietal cortex from 23 beagle dogs (8.1-12.4 years) were treated for 2.8 years in one of four treatment groups: i.e., control food-control behavioral enrichment (CC); control food-behavioral enrichment (CE); antioxidant food-control behavioral enrichment (CA); enriched environment-antioxidant-fortified food (EA). We analyzed the levels of the oxidative stress biomarkers, i.e., protein carbonyls, 3-nitrotyrosine (3-NT), and the lipid peroxidation product, 4-hydroxynonenal (HNE), and observed a decrease in their levels on all treatments when compared to control, with the most significant effects found in the combined treatment, EA. Since EA treatment was most effective, we also carried out a comparative proteomics study to identify specific brain proteins that were differentially expressed and used a parallel redox proteomics approach to identify specific brain proteins that were less oxidized following EA. The specific protein carbonyl levels of glutamate dehydrogenase [NAD (P)], glyceraldehyde-3-phosphate dehydrogenase (GAPDH), alpha-enolase, neurofilament triplet L protein, glutathione-S-transferase (GST) and fascin actin bundling protein were significantly reduced in brain of EA-treated dogs compared to control. We also observed significant increases in expression of Cu/Zn superoxide dismutase, fructose-bisphosphate aldolase C, creatine kinase, glutamate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase. The increased expression of these proteins and in particular Cu/Zn SOD correlated with improved cognitive function. In addition, there was a significant increase in the enzymatic activities of glutathione-S-transferase (GST) and total superoxide dismutase (SOD), and significant increase in the protein levels of heme oxygenase (HO-1) in EA treated dogs compared to control. These findings suggest that the combined treatment reduces the levels of oxidative damage and improves the antioxidant reserve systems in the aging canine brain, and may contribute to improvements in learning and memory. These observations provide insights into a possible neurobiological mechanism underlying the effects of the combined treatment. These results support the combination treatments as a possible therapeutic approach that could be translated to the aging human population who are at risk for age-related neurodegenerative disorders, including Alzheimer's disease.

Glutathione elevation by gamma-glutamyl cysteine ethyl ester as a potential therapeutic strategy for preventing oxidative stress in brain mediated by in vivo administration of adriamycin: Implication for chemobrain.

Oxidative stress in heart and brain by the cancer chemotherapeutic drug adriamycin (ADR), used for treating solid tumors, is well established. Long-term treatment with ADR in breast cancer patients has led to symptoms of cardiomyopathy. Less well recognized, but increasingly well documented, is cognitive dysfunction. After chemotherapy, free radical-mediated oxidative stress has been reported in both heart and brain. We recently showed a significant increase in protein oxidation and lipid peroxidation in brain isolated from mice injected intraperitonially (i.p) with ADR. Systemic administration of ADR also induces tumor necrosis factor-alpha (TNF-alpha), which leads to production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in brain. Circulating TNF also causes mitochondrial dysfunction, leading to apoptotic pathways in brain. Inducible nitric oxide synthase also plays a role in ADR-induced TNF-mediated neurotoxicity. In addition, we previously showed a significant decrease in glutathione (GSH) levels in brain isolated from ADR injected mice, along with increased expression of multidrug-resistant protein-1 (MRP-1), glutathione-S-transferase (GST), glutathione peroxidase (GPx), and glutathione reductase (GR). There was a significant decrease in activity of brain GST. The present study was designed to test the hypothesis that, by elevating brain levels of GSH, the brain would be protected against oxidative stress in ADR-injected mice. gamma-Glutamyl cysteine ethyl ester (GCEE), a precursor of glutathione, injected i.p. (150 mg/ kg body weight) 4 hr prior ADR injection (20 mg/kg body weight) led to significantly decreased protein oxidation and lipid peroxidation in subsequently isolated mice brain compared with brain isolated from ADR-injected mice without GCEE. The GSH levels were restored to the level of brain isolated from saline-injected mice. Furthermore, the enzyme activity of GST was increased in brain isolated from ADR-injected mice previously injected with GCEE compared with the brain isolated from ADR-injected mice previously injected with saline. These results are discussed with regard to potential pharmacological prevention of brain cognitive dysfunction in patients receiving ADR chemotherapy.

In vivo administration of D609 leads to protection of subsequently isolated gerbil brain mitochondria subjected to in vitro oxidative stress induced by amyloid beta-peptide and other oxidative stressors: relevance to Alzheimer's disease and other oxidative stress-related neurodegenerative disorders.

Tricyclodecan-9-yl-xanthogenate (D609) has in vivo and in vitro antioxidant properties. D609 mimics glutathione (GSH) and has a free thiol group, which upon oxidation forms a disulfide. The resulting dixanthate is a substrate for glutathione reductase, regenerating D609. Recent studies have also shown that D609 protects brain in vivo and neuronal cultures in vitro against the potential Alzheimer's disease (AD) causative factor, Abeta(1-42)-induced oxidative stress and cytotoxicity. Mitochondria are important organelles with both pro- and antiapoptotic factor proteins. The present study was undertaken to test the hypothesis that intraperitoneal injection of D609 would provide neuroprotection against free radical-induced, mitochondria-mediated apoptosis in vitro. Brain mitochondria were isolated from gerbils 1 h post injection intraperitoneally (ip) with D609 and subsequently treated in vitro with the oxidants Fe(2+)/H(2)O(2) (hydroxyl free radicals), 2,2-azobis-(2-amidinopropane) dihydrochloride (AAPH, alkoxyl and peroxyl free radicals), and AD-relevant amyloid beta-peptide 1-42 [Abeta(1-42)]. Brain mitochondria isolated from the gerbils previously injected ip with D609 and subjected to these oxidative stress inducers, in vitro, showed significant reduction in levels of protein carbonyls, protein-bound hydroxynonenal [a lipid peroxidation product], 3-nitrotyrosine, and cytochrome c release compared to oxidant-treated brain mitochondria isolated from saline-injected gerbils. D609 treatment significantly maintains the GSH/GSSG ratio in oxidant-treated mitochondria. Increased activity of glutathione S-transferase, glutathione peroxidase, and glutathione reductase in brain isolated from D609-injected gerbils is consistent with the notion that D609 acts like GSH. These antiapoptotic findings are discussed with reference to the potential use of this brain-accessible glutathione mimetic in the treatment of oxidative stress-related neurodegenerative disorders, including AD.

Pin1 in Alzheimer's disease.

Proteolytic processing and phosphorylation of amyloid precursor protein (APP), and hyperphosphorylation of tau protein, have been shown to be increased in Alzheimer's disease (AD) brains, leading to increased production of beta-amyloid (Abeta) peptides and neurofibrillary tangles, respectively. These observations suggest that phosphorylation events are critical to the understanding of the pathogenesis and treatment of this devastating disease. Pin-1, one of the peptidyl-prolyl isomerases (PPIase), catalyzes the isomerization of the peptide bond between pSer/Thr-Pro in proteins, thereby regulating their biological functions which include protein assembly, folding, intracellular transport, intracellular signaling, transcription, cell cycle progression and apoptosis. A number of previous studies have shown that Pin1 is co-localized with phosphorylated tau in AD brain, and shows an inverse relationship to the expression of tau. Pin1 protects neurons under in vitro conditions. Moreover, recent studies demonstrate that APP is a target for Pin1 and thus, in Abeta production. Furthermore, Pin1 was found to be oxidatively modified and to have reduced activity in the hippocampus in mild cognitive impairment (MCI) and AD. Because of the diverse functions of Pin1, and the discovery that this protein is one of the oxidized proteins common to both MCI and AD brain, the question arises as to whether Pin1 is one of the driving forces for the initiation or progression of AD pathogenesis, finally leading to neurodegeneration and neuronal apoptosis. In the present review, we discuss the role of Pin1 with respect to Alzheimer's disease.