Publications (20)176.42 Total impact
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Article: Deletion of tau attenuates heat shock-induced injury in cultured cortical neurons.
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ABSTRACT: The microtubule-associated protein tau has been implicated in beta-amyloid- and glutamate-induced neurotoxicity. However, the potential role of tau in response to other insults to neurons remains unclear. In this study, we examined whether deletion of tau would change cell injury induced by heat shock in primary cultures of cortical neurons. After 30 min of a 45 degrees C heat shock, lactate dehydrogenase (LDH) release increased, reaching a peak at 6 hr in wild-type (WT) neurons. A significantly lower LDH release, with a peak delayed by 24 hr, was detected in tau knockout (TKO) neurons. After heat shock treatment, MAP-2 and tubulin staining of the processes of WT neurons revealed more dramatic abnormalities than in TKO neurons. Both WT and TKO neurons exhibited a similar elevation of HSP70 level but different time courses of Akt phosphorylation. In contrast to an early, brief response in WT neurons, TKO neurons displayed a late, but long-lasting increase in phosphorylation of Akt and its downstream target, glycogen synthase kinase 3beta. Additionally, inhibition of Akt activity aggravated the cell morbidity caused by heat shock exposure in both WT and TKO neurons, indicating a protective role of Akt against cell injury. In conclusion, our results demonstrate that deletion of tau attenuated heat shock-induced neuronal injury. Enhanced Akt response in the absence of endogenous tau is suggested to represent a compensatory mechanism for regulating cell reactions to stress stimuli.Journal of Neuroscience Research 08/2009; 88(1):102-10. · 2.74 Impact Factor -
Article: Senescence accelerated mouse strain is sensitive to neurodegeneration induced by mild impairment of oxidative metabolism.
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ABSTRACT: Neuronal loss and impairment of oxidative metabolism are frequently observed in aging associated neurodegenerative diseases. Thiamine deficiency (TD) induces the region selective neuronal loss in the brain, which has been used to model neurodegeneration, accompanied by mild impairment of oxidative metabolism. C57BL/6 mice were commonly used animals for TD experiments; however, the individual variations among C57BL/6 mice in response to TD limited the consistence of brain pathology. The senescence accelerated prone 8 (SAMP8) mouse strain exhibits age-related morphological changes in the brain and deficits in learning and memory. In this study, we compared the effects of TD on SAMP8 mice, senescence accelerated resistant 1 (SAMR1) mice and C57BL/6 mice. TD-induced body weight loss in SAMP8 mice was much greater than in SAMR1 and C57BL/6 mice. In addition, earlier and more severe loss of neurons in the submedial thalamic nucleus (SmTN) of the thalamus was detected in the SAMP8 mice. After 8 days of TD (TD8), the loss of NeuN-positive neurons in the SmTN of SAMP8, SAMR1 and C57BL/6 mice was 65%, 50%, and 36%, respectively. TD also caused accumulation of amyloid precursor protein (APP) in the thalamus. After TD10, APP immunoreactivity in the thalamus of SAMP8 was much more intense than that of SAMR1 and C57BL/6 mice. These results suggest that SAMP8 mice are sensitive to TD and therefore offer a useful model for studying aging related neurodegeneration caused by the impairment of oxidative metabolism.Brain research 03/2009; 1264:111-8. · 2.46 Impact Factor -
Article: Thiamine deficiency increases β-secretase activity and accumulation of β-amyloid peptides.
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ABSTRACT: Thiamine pyrophosphate (TPP) and the activities of thiamine-dependent enzymes are reduced in Alzheimer's disease (AD) patients. In this study, we analyzed the relationship between thiamine deficiency (TD) and amyloid precursor protein (APP) processing in both cellular and animal models of TD. In SH-SY5Y neuroblastoma cells overexpressing APP, TD promoted maturation of β-site APP cleaving enzyme 1 (BACE1) and increased β-secretase activity which resulted in elevated levels of β-amyloid (Aβ) as well as β-secretase cleaved C-terminal fragment (β-CTF). An inhibitor of β-secretase efficiently reduced TD-induced up-regulation of Aβ and β-CTF. Importantly, thiamine supplementation reversed the TD-induced alterations. Furthermore, TD treatment caused a significant accumulation of reactive oxygen species (ROS); antioxidants suppressed ROS production and maturation of BACE1, as well as TD-induced Aβ accumulation. On the other hand, exogenous Aβ(1-40) enhanced TD-induced production of ROS. A study on mice indicated that TD also caused Aβ accumulation in the brain, which was reversed by thiamine supplementation. Taken together, our study suggests that TD could enhance Aβ generation by promoting β-secretase activity, and the accumulation of Aβ subsequently exacerbated TD-induced oxidative stress.Neurobiology of aging 03/2009; 32(1):42-53. · 5.94 Impact Factor -
Article: Truncated tau at D421 is associated with neurodegeneration and tangle formation in the brain of Alzheimer transgenic models.
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ABSTRACT: In addition to tau hyperphosphorylation, tau truncation is also detected in Alzheimer's disease (AD) patients. In the brain of AD transgenic mouse models, the pathological details of truncated tau are not well characterized. In this study, we analyzed spatial relationships among tau truncation, tau phosphorylation and neurodegeneration or tangle formation in a tau(P301L) single transgenic mouse model and a triple transgenic mouse model that produces both amyloid plaques, and neurofibrillary tangles. During development of tau pathology, the spatial relationship between hyperphosphorylation and truncation of tau exhibited a shift from colocalization at low densities of hyperphosphorylated tau to partial dissociation at high densities. Importantly, we detected a few neurons that contained abundant truncated tau but were lacking hyperphosphorylation, and these neurons exhibited remarkable nuclear condensation. In the case of colocalization, truncated tau was commonly associated with high immunoreactivity of hyperphosphorylated tau and dense Gallyas silver staining. Taken together, our study shows that tau truncation appears after tau hyperphosphorylation in the brain of two transgenic mouse models, and that accumulation of truncated tau, in the absence or the presence of phosphorylated tau, is closely associated with a subset of neurons undergoing degeneration or containing neurofibrillary tangles.Acta Neuropathologica 03/2009; 117(6):687-97. · 9.32 Impact Factor -
Article: Role of caspase-3 in tau truncation at D421 is restricted in transgenic mouse models for tauopathies.
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ABSTRACT: Truncated tau is widely detected in Alzheimer's disease brain, and caspase-3 has been considered as a major executioner for tau truncation at aspartate421 (D421), according to its capability of cleaving recombinant tau in vitro. Here we investigated the relationship between D421 truncated tau and caspase-3 in two transgenic mouse models for tauopathies. In adult transgenic mice, activated caspase-3 could not be detected in neurons containing truncated tau, with the exception of a few glia-like cells or neurons in postnatal mice. Caspase-3 expression exhibited a dramatic decrease at the early development stage, and kept at constantly low levels during adult stages in both wild type and transgenic mice. On the other hand, co-incubating brain homogenates from adult tau transgenic mice and ethanol-treated postnatal mice promoted tau truncation at D421, which was mildly reduced by caspase inhibitor, but completely suppressed by phosphatase inhibitor, indicating that hyperphosphorylated tau becomes a poor substrate for truncation at D421. Taken together, our study shows that insufficient caspase-3 expression and hyperphosphorylated status of tau in the adult transgenic mouse brain restrict caspase-3 as an efficient enzyme for tau truncation in vivo. Clearly, there is a caspase-3 independent mechanism responsible for tau truncation at D421 in these models.Journal of Neurochemistry 03/2009; 109(2):476-84. · 4.06 Impact Factor -
Article: Improving the specificity of immunological detection in aged human brain tissue samples.
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ABSTRACT: Immunological analyses of aged human brain tissues are widely used in characterizing the physiology or pathophysiology of brain aging or neurological diseases such as Alzheimer's disease. The primary antibodies used in immunological detection mainly originate from rabbit and mouse species. In the present study, we showed an unexpected cross-immunoreactivity between anti-rabbit immunoglobulin G and diffuse lipofuscin-associated protein(s) in aged human brain tissues. In immunoblotting analysis of aged human brain samples, anti-rabbit secondary antibody alone produces a sharp band of approximately 180 kDa, whereas anti-mouse antibody does not show this cross-reaction. Immunohistochemical localization of cross-immunoreactivity found that the cross-reactive protein(s) were mainly associated with diffuse and weak autofluorescence in the cytoplasm of neurons. This nonspecific cross-immunoreactivity produces sufficient intensity of non-specific immunostaining signals that are easily mis-recognized as specific immunoreactivity, and can generate misleading data. The above nonspecific cross-reactivity with anti-rabbit secondary antibody in aged human brain tissues could be significantly reduced or abolished by pretreating tissues with 1% sodium borohydride or/and adding 0.5% Tween-20 into the secondary antibody dilution buffer. When these modifications are included in the protocol, specific immunoreactivity (such as phospho-tau pT231) was unaffected, or slightly improved. Our study suggests that caution should be taken when performing immunological analyses on aged human brain samples with rabbit polyclonal antibody, and that modification of the experimental protocol is generally required to minimize the aforementioned nonspecificity.International Journal of Physiology, Pathophysiology and Pharmacology 01/2009; 2(1):29-35. -
Article: Subclinical concentration of sevoflurane potentiates neuronal apoptosis in the developing C57BL/6 mouse brain.
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ABSTRACT: The effect of general anesthetics on the developing brain is receiving growing attention. Nonetheless, there remains a paucity of evidence regarding the effect of sevoflurane, a widely used anesthetic in pediatric anesthesia. This study was designed to investigate the effect of sevoflurane on nerve cell apoptosis in the developing brain. Techniques to detect cell apoptosis included immunohistochemistry of cleaved caspase-3 and single-strand DNA, as well as electron microscopy. Elevated cleaved caspase-3 was also validated semi-quantitatively by immunoblotting assay. Mouse pups (day 7 postnatal) were subjected to sevoflurane inhalation. Twelve hours later, dramatically increased cleaved caspase-3 and single-strand DNA immunoreactivity were detected in the pup brains. Immunoblotting assay of cleaved caspase-3 revealed a significant increase after anesthetic exposure. Electron microscopy disclosed typical apoptotic morphology of the degenerative nerve cells. Blood glucose levels in the anesthetized group were not different from those of the control group, indicating that the neuronal apoptosis observed in the anesthetized group was not the result of hypoglycemia. Our results indicate that subanesthetic concentration of sevoflurane can trigger neuronal apoptosis in the postnatal mouse brain.Neuroscience Letters 11/2008; 447(2-3):109-14. · 2.11 Impact Factor -
Article: Pin1 has opposite effects on wild-type and P301L tau stability and tauopathy.
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ABSTRACT: Tau pathology is a hallmark of many neurodegenerative diseases including Alzheimer disease (AD) and frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17). Genetic tau mutations can cause FTDP-17, and mice overexpressing tau mutants such as P301L tau are used as AD models. However, since no tau mutations are found in AD, it remains unclear how appropriate tau mutant mice are as an AD model. The prolyl isomerase Pin1 binds and isomerizes tau and has been implicated in protecting against neurodegeneration, but whether such Pin1 regulation is affected by tau mutations is unknown. Consistent with earlier findings that Pin1 KO induces tauopathy, here we demonstrate that Pin1 knockdown or KO increased WT tau protein stability in vitro and in mice and that Pin1 overexpression suppressed the tauopathy phenotype in WT tau transgenic mice. Unexpectedly, Pin1 knockdown or KO decreased P301L tau protein stability and abolished its robust tauopathy phenotype in mice. In contrast, Pin1 overexpression exacerbated the tauopathy phenotype in P301L tau mice. Thus, Pin1 has opposite effects on the tauopathy phenotype depending on whether the tau is WT or a P301L mutant, indicating the need for disease-specific therapies for tauopathies.Journal of Clinical Investigation 06/2008; 118(5):1877-89. · 15.39 Impact Factor -
Article: Biophysical and biochemical characterization of the intrinsic fluorescence from neurofibrillary tangles.
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ABSTRACT: Recently, we developed a novel fluorescent method named intrinsic fluorescence induction that allows direct visualization of neurofibrillary pathology without introducing exogenous chromogens. In the present study, we further characterized the properties of this novel red fluorescence biophysically, biochemically, and neuropathologically. In vitro spectrofluorometry and in situ emission scan show that the intrinsic fluorescence of neurofibrillary tangles has a long emission wavelength peak at 620 nm and a large Stoke's shift of 70 nm. Dephosphorylation of Alzheimer's disease brain sections with alkaline phosphatase or denaturation with guanidine only causes a subtle reduction in the induced fluorescence of neurofibrillary tangles, while hydrofluoric acid or formic acid completely eliminates the fluorescence. Chemical modification of residue serine, but not tyrosine or tryptophan, reduced the intensity of induced fluorescence significantly. The induced fluorophore, thus, has unique properties, and its generation likely depends on the particular conformation of paired helical filaments, which may in turn depend on tau hyperphosphorylation.Neurobiology of Aging 07/2006; 27(6):823-30. · 6.19 Impact Factor -
Article: Expression of microsomal epoxide hydrolase is elevated in Alzheimer's hippocampus and induced by exogenous beta-amyloid and trimethyl-tin.
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ABSTRACT: The brain is a potential target for drugs and environmental toxins. Microsomal epoxide hydrolase (mEH) is one of several critical biotransformation enzymes in xenobiotic metabolism and detoxification. In the present study, we report that the expression of mEH is significantly elevated in the hippocampus and associated cortex, but not in the cerebellum, in Alzheimer's disease (AD) patients. A large proportion of the mEH-positive cells are located around beta-amyloid plaques. The mEH-positive-staining cells are astrocytes and pyramidal neurons. Western blotting analysis confirmed increased expression of mEH in AD hippocampal tissues. In primary hippocampal glial culture, beta-amyloid aggregation stimulated mEH expression in the astrocytes, which displayed a patchy distribution. An environmental neurotoxic agent, trimethyl-tin, also activated mEH expression in rat hippocampus and entorhinal cortex. The present study demonstrates a significant increase in mEH expression in the AD hippocampus, a region showing abundant neuropathology in AD. The expression of mEH could also be elevated by exposure to exogenous beta-amyloid in vitro and environmental toxins in vivo. Our studies suggest that mEH may play a role in pathogenesis of neurodegeneration in response to environmental stress.European Journal of Neuroscience 05/2006; 23(8):2027-34. · 3.63 Impact Factor -
Article: Expression of microsomal epoxide hydrolase is elevated in Alzheimer's hippocampus and induced by exogenous β‐amyloid and trimethyl‐tin
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ABSTRACT: The brain is a potential target for drugs and environmental toxins. Microsomal epoxide hydrolase (mEH) is one of several critical biotransformation enzymes in xenobiotic metabolism and detoxification. In the present study, we report that the expression of mEH is significantly elevated in the hippocampus and associated cortex, but not in the cerebellum, in Alzheimer's disease (AD) patients. A large proportion of the mEH-positive cells are located around β-amyloid plaques. The mEH-positive-staining cells are astrocytes and pyramidal neurons. Western blotting analysis confirmed increased expression of mEH in AD hippocampal tissues. In primary hippocampal glial culture, β-amyloid aggregation stimulated mEH expression in the astrocytes, which displayed a patchy distribution. An environmental neurotoxic agent, trimethyl-tin, also activated mEH expression in rat hippocampus and entorhinal cortex. The present study demonstrates a significant increase in mEH expression in the AD hippocampus, a region showing abundant neuropathology in AD. The expression of mEH could also be elevated by exposure to exogenous β-amyloid in vitro and environmental toxins in vivo. Our studies suggest that mEH may play a role in pathogenesis of neurodegeneration in response to environmental stress.European Journal of Neuroscience 04/2006; 23(8):2027 - 2034. · 3.63 Impact Factor -
Article: The prolyl isomerase Pin1 regulates amyloid precursor protein processing and amyloid-beta production.
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ABSTRACT: Neuropathological hallmarks of Alzheimer's disease are neurofibrillary tangles composed of tau and neuritic plaques comprising amyloid-beta peptides (Abeta) derived from amyloid precursor protein (APP), but their exact relationship remains elusive. Phosphorylation of tau and APP on certain serine or threonine residues preceding proline affects tangle formation and Abeta production in vitro. Phosphorylated Ser/Thr-Pro motifs in peptides can exist in cis or trans conformations, the conversion of which is catalysed by the Pin1 prolyl isomerase. Pin1 has been proposed to regulate protein function by accelerating conformational changes, but such activity has never been visualized and the biological and pathological significance of Pin1 substrate conformations is unknown. Notably, Pin1 is downregulated and/or inhibited by oxidation in Alzheimer's disease neurons, Pin1 knockout causes tauopathy and neurodegeneration, and Pin1 promoter polymorphisms appear to associate with reduced Pin1 levels and increased risk for late-onset Alzheimer's disease. However, the role of Pin1 in APP processing and Abeta production is unknown. Here we show that Pin1 has profound effects on APP processing and Abeta production. We find that Pin1 binds to the phosphorylated Thr 668-Pro motif in APP and accelerates its isomerization by over 1,000-fold, regulating the APP intracellular domain between two conformations, as visualized by NMR. Whereas Pin1 overexpression reduces Abeta secretion from cell cultures, knockout of Pin1 increases its secretion. Pin1 knockout alone or in combination with overexpression of mutant APP in mice increases amyloidogenic APP processing and selectively elevates insoluble Abeta42 (a major toxic species) in brains in an age-dependent manner, with Abeta42 being prominently localized to multivesicular bodies of neurons, as shown in Alzheimer's disease before plaque pathology. Thus, Pin1-catalysed prolyl isomerization is a novel mechanism to regulate APP processing and Abeta production, and its deregulation may link both tangle and plaque pathologies. These findings provide new insight into the pathogenesis and treatment of Alzheimer's disease.Nature 04/2006; 440(7083):528-34. · 36.28 Impact Factor -
Article: The prolyl isomerase Pin1 regulates amyloid precursor protein processing and amyloid- production
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ABSTRACT: Neuropathological hallmarks of Alzheimer's disease are neurofibrillary tangles composed of tau and neuritic plaques comprising amyloid-Nature 03/2006; 440(7083):528-534. · 36.28 Impact Factor -
Article: P38 MAP kinase is activated at early stages in Alzheimer's disease brain.
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ABSTRACT: The regional, cellular, and subcellular localization of phosphorylated p38 MAPK (pp38) was examined by immunocytochemistry, immuofluorescent multiple labeling, and immunoblotting of extracts as well as immunoprecipitates of human postmortem tissue from control and Alzheimer's disease (AD) cases at different Braak stages. "Early AD" cases (Braak stages IV-V) and a subset of Braak stage VI cases have high levels of pp38 immunoreactivity, with the most dense immunoreactivity located in CA2 and subiculum followed by CA1 in the hippocampus. On the contrary, very little pp38 was detected in age-matched controls (Braak stages 0-II). More importantly, as revealed by various multiple labeling experiments, pp38 immunoreactivity is mainly located in neurons bearing early neurofibrillary pathology, but not in typically fibrillar tangles that are densely stained by thioflavin-S. Most pp38-positive neurons only contain a small amount of phospho-tau. Additionally, pp38 immunoreactivity was not associated with senile plaques. At the subcellular level, pp38-immunoreactive granules are usually larger than the granules stained with the lysosomal marker cathepsin D. Immunoblotting with different extraction buffers and immunoprecipitation indicate that pp38 does not or only loosely binds to phospho-tau. Taken together, this study demonstrates that p38 MAPK is activated at early stages of neurofibrillary degeneration in AD hippocampus. The p38 activation may also be linked to neurodegeneration through mechanisms other than neurofibrillary tangle formation.Experimental Neurology 11/2003; 183(2):394-405. · 4.70 Impact Factor -
Article: Role of the prolyl isomerase Pin1 in protecting against age-dependent neurodegeneration.
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ABSTRACT: The neuropathological hallmarks of Alzheimer's disease and other tauopathies include senile plaques and/or neurofibrillary tangles. Although mouse models have been created by overexpressing specific proteins including beta-amyloid precursor protein, presenilin and tau, no model has been generated by gene knockout. Phosphorylation of tau and other proteins on serine or threonine residues preceding proline seems to precede tangle formation and neurodegeneration in Alzheimer's disease. Notably, these phospho(Ser/Thr)-Pro motifs exist in two distinct conformations, whose conversion in some proteins is catalysed by the Pin1 prolyl isomerase. Pin1 activity can directly restore the conformation and function of phosphorylated tau or it can do so indirectly by promoting its dephosphorylation, which suggests that Pin1 is involved in neurodegeneration; however, genetic evidence is lacking. Here we show that Pin1 expression is inversely correlated with predicted neuronal vulnerability and actual neurofibrillary degeneration in Alzheimer's disease. Pin1 knockout in mice causes progressive age-dependent neuropathy characterized by motor and behavioural deficits, tau hyperphosphorylation, tau filament formation and neuronal degeneration. Thus, Pin1 is pivotal in protecting against age-dependent neurodegeneration, providing insight into the pathogenesis and treatment of Alzheimer's disease and other tauopathies.Nature 08/2003; 424(6948):556-61. · 36.28 Impact Factor -
Article: Localization of beta-secretase memapsin 2 in the brain of Alzheimer's patients and normal aged controls.
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ABSTRACT: Chronic accumulation of beta-amyloid in the brain has been shown to result in complex molecular and cellular changes that accompany neurodegeneration in Alzheimer's disease (AD). In this study, we examined the expression of a newly identified beta-secretase, memapsin 2 (M2) or beta-site APP cleaving enzyme in deparaffinized sections from 10 AD patients and 10 aged matched controls and in frozen samples of parietal cortex from 11 AD and 8 controls. M2 is mainly expressed in neurons, with high levels in CA4 to CA2 regions and transentorhinal cortex and low or intermediate levels in CA1, subiculum, and granule cells of the dentate gyrus. The majority of AD brains showed an increase of M2 expression in the CA1, but a decrease in the transentorhinal cortex. A subset of controls and AD patients had high M2 expression in parietal neocortex. Double-staining revealed that senile plaques are not directly associated with the soma of M2-expressing neurons. Neurofibrillary tangles were associated with lower M2 expression in AD. These data indicate that beta-secretase M2 may not be straightforwardly involved in amyloid plaque formation in AD brain.Experimental Neurology 06/2002; 175(1):10-22. · 4.70 Impact Factor -
Article: Comparative analysis of an improved thioflavin-s stain, Gallyas silver stain, and immunohistochemistry for neurofibrillary tangle demonstration on the same sections.
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ABSTRACT: An improved thioflavin-S stain, Gallyas silver stain, and two immunostainings were quantitatively compared for demonstration of neurofibrillary tangles (NFTs) on the same sections. Sections of hippocampal formation from seven cases of Alzheimer's disease (AD) were immunofluorescently stained with a commercially available polyclonal NFT antibody or a PHF-1 monoclonal antibody, followed by an improved thioflavin-S stain, and finally by Gallyas silver staining. The thioflavin-S method was improved by using a combination quenching method that removes background autofluorescence without remarkable tissue damage and by post-treatment with concentrated phosphate buffer, which minimizes photobleaching. PHF-1 or NFT immunostaining is much less sensitive than the improved thioflavin-S staining and Gallyas silver staining, particularly in the transentorhinal region. Moreover PHF-1 immunoreactivity varied greatly among AD individuals. Thioflavin-S staining and Gallyas silver staining show almost the same sensitivity in NFT demonstration, but only the former depends on the secondary protein structure of NFTs. This study suggests that the improved thioflavin-S staining is a simple, sensitive, and consistent method for demonstration of neurofibrillary pathology.Journal of Histochemistry and Cytochemistry 05/2002; 50(4):463-72. · 2.72 Impact Factor -
Article: L-arginine promotes the repair process of endothelium in ischemia-reperfused arteries of rats.
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ABSTRACT: OBJECTIVE: To observe effects of arginine on art erial endothelium injured by ischemia-reperfusion (IR), and explore its possibl e mechanism. METHODS: Fifty-four rats were divided into 3 groups and treate d in respective ways: (1) drinking tap water as the control; (2) drinking tap wa ter containing 2.5% L-arginine; (3) drinking tap water containing 2.5% L-arginine together with intraperitoneal injection of N(G)-nitro-L-arginine methylester 5 mg/kg/d. A segment of the common carotid artery was occluded for 1 h, and then reperfused. Samples taken at different post-IR t ime from the segment were prepared for the ultrastructural and Ce-H(2)O(2) cyto chemical observation. The naked index (NI) of internal elastic lamina (IEL) was measured for comparing the endothelial injure extent and its repair process. RESULTS: Less damage of endothelial cells (EC), more platelets adhering to naked IEL and more regenerating EC were observed in Group 2. The NI values of samples taken at 1, 2, 3 d after the IR were respectively 0.92plus minus0.08, 0.88plus minus0.03 and 0.41plus minus0.02 in Group 1, and reduced to 0.52plus minus0.05, 0.19plus minus0.08 and 0.06plus minus0.01 in Grou p 2 (P<0.05-0.01). In Group 3, the endothelium da mage was not alleviated, and so were the NI. The Ce-H(2)O(2) particles deposite d on the lumen surface of endothelium were much less in Group 2 than in Groups 1 and 3. CONCLUSIONS: L-arginine promotes the repair process of IR-in jured endothelium probably through the removal of oxygen free radicals by NO.Chinese Journal of Traumatology (English Edition) 08/2000; 3(3):136-140. -
Article: A novel fluorescent method for direct visualization of neurofibrillary pathology in Alzheimer's disease
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ABSTRACT: Methods currently available for detecting neurofibrillary pathology are indirect and depend on staining with exogenous chemicals or antibodies. In the present study, we report a novel method named intrinsic fluorescence induction (IFI), which allows direct visualization of neurofibrillary tangles (NFTs), neuropil threads (NTs), and neuritic plaques (NPs) in tissue sections of Alzheimer's disease (AD) brain. The IFI method is based on both induction of a red intrinsic fluorescence and quenching red background autofluorescence. The IFI procedure includes sustained hydrophobic treatment, protein secondary structure enhancement and incubation in high concentration of phosphate buffer. Following this procedure, a unique red fluorescence is generated from the structures of NFTs, NTs, and NPs in brain sections from AD patients. Sequential application of mild permanganate oxidation and 1% sodium borohydride selectively removes the red background autofluorescence, while the latter enhances the intrinsic fluorescence of neurofibrillary pathology. Comparative studies reveal that the IFI method is as sensitive as Gallyas silver staining, and more sensitive than Bielschowsky silver staining or PHF-1 immunostaining in detecting NFTs in the pre-α layer of entorhinal cortex and the pri-α layer of the entorhinal/transentorhinal cortex. Furthermore, the IFI method is sensitive in displaying plaque neurites and threads, but not NFTs in the hippocampus. This novel finding provides a direct method for detecting neurofibrillary pathology in particular regions of AD brain and a novel tool for AD research.Journal of Neuroscience Methods. -
Article: Localization of β-Secretase Memapsin 2 in the Brain of Alzheimer's Patients and Normal Aged Controls
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ABSTRACT: Chronic accumulation of β-amyloid in the brain has been shown to result in complex molecular and cellular changes that accompany neurodegeneration in Alzheimer's disease (AD). In this study, we examined the expression of a newly identified β-secretase, memapsin 2 (M2) or β-site APP cleaving enzyme in deparaffinized sections from 10 AD patients and 10 aged matched controls and in frozen samples of parietal cortex from 11 AD and 8 controls. M2 is mainly expressed in neurons, with high levels in CA4 to CA2 regions and transentorhinal cortex and low or intermediate levels in CA1, subiculum, and granule cells of the dentate gyrus. The majority of AD brains showed an increase of M2 expression in the CA1, but a decrease in the transentorhinal cortex. A subset of controls and AD patients had high M2 expression in parietal neocortex. Double-staining revealed that senile plaques are not directly associated with the soma of M2-expressing neurons. Neurofibrillary tangles were associated with lower M2 expression in AD. These data indicate that β-secretase M2 may not be straightforwardly involved in amyloid plaque formation in AD brain.Experimental Neurology.
Top co-authors
Top Journals
Institutions
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2008–2009
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Fudan University
- • State Key Laboratory of Medical Neurobiology
- • Department of Anesthesiology
Shanghai, Shanghai Shi, China
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2003–2008
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Beth Israel Deaconess Medical Center
- Department of Medicine
Boston, MA, USA
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2002–2006
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University of Kentucky
- Department of Anatomy & Neurobiology
Lexington, KY, USA
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