Alzheimer Disease: Sun Y

Sun Y, Lai MS, Lu CJ, Chen RC. · Department of Neurology, En Chu Kong Hospital, Taipei, Taiwan. · Eur J Neurol. · Pubmed #18290848 No free full text.

Abstract: The aims of this study were to evaluate the duration of acetylcholinesterase inhibitors (AChEI) utilization as well as the patients' cognition maintenance. This study was using panel data from the Bureau of National Health Insurance (BNHI) of Taiwan from 2001 to 2004. Patients with mild or moderate AD were prescribed AChEI (donepezil, rivastigmine, or galantamine). By the regulation of BNHI, if the score of Mini-Mental Status Examination worsened by more than two points or clinical dementia rating (CDR) worsened by one or more grades in the follow-up every half year, the AChEI treatment would be terminated. Kaplan-Meier product-limit method was used to estimate duration of drug utilization. Regression model was performed to analyse the factors affecting the discontinuation of AChEI treatment. Our results showed female are more and younger than male in mild to moderate Alzheimer's dementia. The mean duration of use of AChEI was 432 days. Only 9.6% of patients maintained stable cognition tests results with continued drug refill for more than 3 years. Discontinuation rate in older patients (age > or =76 years) was higher than those in younger age (P = 0.0009). The average duration for AChEI therapy is around 14 months. The elderly are at high risk for treatment discontinuation.

Liu J, Rasul I, Sun Y, Wu G, Li L, Premont RT, Suo WZ. · From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128. · J Biol Chem. · Pubmed #19478075 No free full text.

Abstract: G protein-coupled receptor kinase 5 (GRK5) deficiency has been linked recently to early Alzheimer disease (AD), but the mechanism by which GRK5 deficiency may contribute to AD pathogenesis remains elusive. Here we report that overexpression of dominant negative mutant of GRK5 (dnGRK5) in a cholinergic neuronal cell line led to decreased acetylcholine (ACh) release. This reduction was fully corrected by pertussis toxin, atropine (a nonselective muscarinic antagonist), or methoctramine (a selective M2/M4 muscarinic receptor antagonist). Consistent with results in cultured cells, high potassium-evoked ACh release in hippocampal slices from young GRK5 knock-out mice was significantly reduced compared with wild type littermates, and this reduced ACh release was also fully corrected by methoctramine. In addition, following treatment with the nonselective muscarinic agonist oxotremorine-M, M2, and M4 receptors underwent significantly reduced internalization in GRK5KO slices compared with wild type slices, as assessed by plasma membrane retention of receptor immunoreactivity, whereas M1 receptor internalization was not affected by loss of GRK5 expression. Moreover, Western blotting revealed no synaptic or cholinergic degenerative changes in young GRK5 knock-out mice. Altogether, these results suggest that GRK5 deficiency leads to a reduced hippocampal ACh release and cholinergic hypofunction by selective impairment of desensitization of presynaptic M2/M4 autoreceptors. Because this nonstructural cholinergic hypofunction precedes the hippocampal cholinergic hypofunction associated with structural cholinergic degeneration and cognitive decline in aged GRK5 knock-out mice, this nonstructural alteration may be an early event contributing to cholinergic degeneration in AD.

Doody RS, Ferris SH, Salloway S, Sun Y, Goldman R, Watkins WE, Xu Y, Murthy AK. · Alzheimer's Disease and Memory Disorders Center, Baylor College of Medicine, 6550 Fannin, Suite 1801, Houston, TX 77030, USA. · Neurology. · Pubmed #19176895 No free full text.

Abstract: BACKGROUND: Treatment of mild cognitive impairment (MCI) with cholinesterase inhibitors may improve symptoms. METHODS: In this multicenter, randomized, placebo-controlled trial, subjects with MCI entered a 3-week placebo run-in period followed by 48 weeks of double-blind donepezil (5 mg/day for 6 weeks, then 10 mg/day for 42 weeks) or placebo treatment. Primary efficacy variables included change from baseline in the modified Alzheimer Disease Assessment Scale-cognitive subscale (ADAS-Cog) and Clinical Dementia Rating Scale-sum of boxes (CDR-SB) after 48 weeks of treatment (modified intention-to-treat analysis). Secondary efficacy measures evaluated cognition, behavior, and function. RESULTS: The dual primary efficacy endpoint was not reached. We noted a small, but significant, decrease in modified ADAS-Cog scores in favor of donepezil at study endpoint. Little change from baseline in CDR-SB and secondary variables was observed for either group. Patient Global Assessment scores favored donepezil at all time points except week 12 (p < or = 0.05). Perceived Deficits Questionnaire scores favored donepezil at week 24 (p = 0.05). Clinical Global Impression of Change-MCI scores favored donepezil only at week 6 (p = 0.04). Adverse events were generally mild or moderate. More donepezil-treated subjects (18.4%) discontinued treatment due to adverse events than placebo-treated subjects (8.3%). CONCLUSIONS: Donepezil demonstrated small but significant improvement on the primary measure of cognition but there was no change on the primary measure of global function. Most other measures of global impairment, cognition, and function were not improved, possibly because these measures are insensitive to change in MCI. Responses on subjective measures suggest subjects perceived benefits with donepezil treatment.

Pietropaolo S, Sun Y, Li R, Brana C, Feldon J, Yee BK. · Laboratory of Behavioral Neurobiology, Swiss Federal Institute of Technology Zurich, Schwerzenbach, Switzerland. · Behav Neurosci. · Pubmed #19170443 No free full text.

Abstract: Gene-environment interactions are known to play a major role in the ethiopathology of several neuropsychiatric disorders, including Alzheimer's disease (AD). The present study investigates whether environmental manipulations, that is, social isolation, may affect the genetic predisposition to develop AD-related traits in a triple transgenic mouse model (3 x Tg-AD), as suggested by our previous study employing physical exercise (Pietropaolo et al., 2008). Mutant and wild type mice of both sexes were housed singly or in groups from weaning, and evaluated behaviorally at 6 to 7 months of age. Independent of sex, the 3 x Tg-AD genotype was associated with enhanced acoustic startle response, improved performance in the cued version of the water maze and a clear impairment in the Y maze. Notably, the female (but not male) mutant mice showed increased anxiety. Although social isolation was effective in modifying several behaviors, it did not exacerbate any of the AD-like symptoms. Our findings demonstrated the differential susceptibility of the 3 x Tg-AD mouse line to environmental manipulations, showing that social isolation did not induce remarkable effects on the genetically determined AD-like symptoms, in contrast to what previously observed with physical exercise.

Lopez OL, Mackell JA, Sun Y, Kassalow LM, Xu Y, McRae T, Li H. · Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA. · J Natl Med Assoc. · Pubmed #19024233 links to  free full text

Abstract: BACKGROUND: Hispanics represent 10% of the U.S. population and are the fastest growing group. Studies show a higher prevalence and incidence of Alzheimer's disease (AD) in Hispanics than in the non-Hispanic white population, with an earlier age of onset. Among the currently estimated 200,000 Hispanics with AD, a significant number remain undiagnosed and untreated, and Hispanic participation in AD clinical trials has been historically low. This study evaluated the efficacy and safety of donepezil hydrochloride (donepezil) in Hispanics with mild-to-moderate AD. METHODS: In this multicenter, open-label, 12-week study conducted in the United States, subjects were Hispanic men or women aged > or =50 years with a diagnosis of mild-to-moderate AD (DSMV-IV and NINCDS/ADRDA criteria), with Mini-Mental State Examination (MMSE) scores of 10-26 (inclusive) at screening. Subjects were treated with donepezil 5 mg/day for 6 weeks followed by 10 mg/day for 6 weeks. Clinical evaluation was performed at baseline, week 6 and week 12. Cognitive improvement was measured using the MMSE, Fuld Object Memory Evaluation (FOME) and Symbol Digit Modality Test (SDMT). Behavioral symptoms and associated caregiver distress were assessed with the Neuropsychiatric Inventory (NPI). RESULTS: One-hundred-six patients with mild-to-moderate AD (mean age 68.6 years) were enrolled (intent to treat, n=97); most chose to have assessments conducted in Spanish. With 12 weeks of treatment, subjects showed statistically significant improvement from baseline on MMSE (P<0.0001), FOME retrieval (P=0.0042), FOME repeated retrieval (P=0.0020) and SDMT correct scores (P<0.0001). The NPI subdomain "apathy/indifference" showed statistically significant improvement (P=0.0010).The NPI Caregiver Distress scale (NPI-D) total score was statistically significantly improved (P=0.0500), suggesting a positive impact on relieving caregivers' burden associated with patient behavior. Most patients tolerated the treatment well, with only 2 discontinuing because of adverse events. The most common (>5%) adverse events were insomnia (9.5%), dizziness (7.6%), diarrhea (5.7%) and nausea (5.7%). CONCLUSION: The cognitive improvement and safety results from this study were consistent with those reported for donepezil in the general population. Increased awareness of AD in the Hispanic population will help more Hispanics with AD to benefit from early diagnosis and effective treatment.

Sun Y, Zhang G, Hawkes CA, Shaw JE, McLaurin J, Nitz M. · Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ont., Canada M5S 3H6. · Bioorg Med Chem. · Pubmed #18635362 No free full text.

Abstract: scyllo-Inositol has shown promise as a potential therapeutic for Alzheimer's disease, by directly interacting with the amyloid beta (Abeta) peptide to inhibit Abeta42 fiber formation. To explore the molecular details of the inositol-Abeta42 interaction, a series of scyllo-inositol derivatives have been synthesized which contain deoxy, fluoro, chloro, and methoxy substitutions. The effects of these compounds on the aggregation cascade of Abeta42 have been investigated using electron microscopy (EM). EM analyses revealed that the 1-deoxy-1-fluoro- and 1,4-dimethyl-scyllo-inositols significantly inhibit the formation of Abeta42 fibers. The other derivatives showed some alterations in the morphology of the Abeta42 fibers produced. These findings indicate the importance of all of the hydroxyl groups of scyllo-inositol for complete inhibition of Abeta aggregation.

Pietropaolo S, Sun Y, Li R, Brana C, Feldon J, Yee BK. · Laboratory of Behavioural Neurobiology, ETH Zurich, Schorenstrasse 16, Schwerzenbach, Switzerland. · Behav Brain Res. · Pubmed #18468702 No free full text.

Abstract: There is growing interest in the effects of voluntary wheel running activity on brain and behaviour in laboratory rodents and their implications to humans. Here, the major findings to date on the impact of exercise on mental health and diseases as well as the possible underlying neurobiological mechanisms are summarised. Several critical modulating factors on the neurobehavioural effects of wheel running exercise are emphasized and discussed--including the amount of wheel running, sex and strain/species differences. We also reported the outcome of an empirical investigation of the impact of wheel running exercise on the expression of both cognitive and non-cognitive phenotypes in a triple (3 x Tg-AD) transgenic mouse model for Alzheimer's disease (AD). Clear sex- and paradigm-specific effects of exercise on the genetically determined phenotypes are illustrated, including the efficacy of wheel running activity in attenuating the sex-specific cognitive deficits. It is concluded that the wheel running paradigm represents a unique environmental manipulation for the investigation of neurobehavioural plasticity in terms of gene-environment interactions relevant to the pathogenesis and therapies of certain neuropsychiatric conditions.

Sun Y, Lu CJ, Chien KL, Chen ST, Chen RC. · Department of Neurology, En Chu Kong Hospital, San-shia, Taipei, Taiwan. · Clin Ther. · Pubmed #18042476 No free full text.

Abstract: BACKGROUND: Elevated serum homocysteine levels have been associated with the development of Alzheimer's dementia (AD). The combined use of a mecobalamin capsule preparation, which contains vitamin B12 0.5 mg with an active methyl base, and an over-the-counter nutritional supplement that contains folic acid 1 mg and pyridoxine hyperchloride 5 mg may be effective as a homocysteine-lowering vitamin regimen. OBJECTIVE: The aim of this study was to determine whether oral multivitamin supplementation containing vitamins B6 and B12 and folic acid would improve cognitive function and reduce serum homocysteine levels in patients with mild to moderate AD. METHODS: This randomized, double-blind, placebocontrolled trial was conducted at En Chu Kong Hospital, Taipei, Taiwan. Male and female patients aged >50 years with mild to moderate AD and normal folic acid and vitamin B12 concentrations were enrolled. All patients received treatment with an acetylcholinesterase inhibitor and were randomized to receive add-on mecobalamin (B12) 500 mg + multivitamin supplement, or placebos, PO QD for 26 weeks. The multivitamin contained pyridoxine (B6) 5 mg, folic acid 1 mg, and other vitamins and iron. Serum homocysteine level was measured and cognitive tests were conducted at baseline and after 26 weeks. The primary efficacy outcome was change in cognition, measured as the change in score from baseline to week 26 on the Alzheimer's Disease Assessment Scale 11-item Cognition subscale. Secondary efficacy outcomes included changes in function in performance of activities of daily living (ADLs) and concentrations of homocysteine, B12, and folic acid. Tolerability was assessed by comparing the 2 study groups with respect to physical examination findings, including changes in vital signs, laboratory test abnormalities, concomitant medication use, and compliance of study medication was assessed using an interview with the patient's caregiver, as well as the monitoring of adverse events (AEs) throughout the study. RESULTS: Eighty-nine patients (45 men, 44 women; all Taiwanese; mean [SD] age, 75 [7.3] years) were enrolled and randomized. Overall, there were no significant differences in cognition or ADL function scores between the 2 groups. At week 26, the mean (SD) between-group difference in serum homocysteine concentration versus placebo was -2.25 (2.85) micromol/L (P = 0.008), and the mean serum concentrations of vitamin B12 and folic acid were significantly higher (but within normal range) in the multivitamin group compared with placebo (., +536.9 [694.4] pg/mL [P < 0.001] and +13.84 ng/mL [11.17] [P = 0.012] at 26 weeks, respectively). The 2 most common AEs were muscle pain (11.1% and 6.8%) and insomnia (8.9% and 9.1%) in the multivitamin and placebo groups, respectively. CONCLUSIONS: In this population of patients with mild to moderate AD in Taiwan, a multivitamin supplement containing vitamins B(6) and B(12) and folic acid for 26 weeks decreased homocysteine concentrations. No statistically significant beneficial effects on cognition or ADL function were found between multivitamin and placebo at 26 weeks.

Black SE, Doody R, Li H, McRae T, Jambor KM, Xu Y, Sun Y, Perdomo CA, Richardson S. · Division of Neurology, Department of Medicine and Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada. · Neurology. · Pubmed #17664405 No free full text.

Abstract: OBJECTIVE: To evaluate the efficacy and safety of donepezil for severe Alzheimer disease (AD). METHODS: Patients with severe AD (Mini-Mental State Examination [MMSE] scores 1 to 12 and Functional Assessment Staging [FAST] scores > or =6) were enrolled in this multinational, double-blind, placebo-controlled trial at 98 sites. Patients were randomized to donepezil 10 mg daily or placebo for 24 weeks. Primary endpoints were the Severe Impairment Battery (SIB) and Clinician's Interview-Based Impression of Change-Plus caregiver input (CIBIC-Plus). Secondary endpoints included the MMSE, the Alzheimer Disease Cooperative Study-Activities of Daily Living-severe version (ADCS-ADL-sev), the Neuropsychiatric Inventory (NPI), the Caregiver Burden Questionnaire (CBQ), and the Resource Utilization for Severe Alzheimer Disease Patients (RUSP). Efficacy analyses were performed in the intent-to-treat (ITT) population using last post-baseline observation carried forward (LOCF). Safety assessments were performed for patients receiving > or =1 dose of donepezil or placebo. RESULTS: Patients were randomized to donepezil (n = 176) or placebo (n = 167). Donepezil was superior to placebo on SIB score change from baseline to endpoint (least squares mean difference 5.32; p = 0.0001). CIBIC-Plus and MMSE scores favored donepezil at endpoint (p = 0.0473 and p = 0.0267). Donepezil was not significantly different from placebo on the ADCS-ADL-sev, NPI, CBQ, or RUSP. Adverse events reported were consistent with the known cholinergic effects of donepezil and with the safety profile in patients with mild to moderate AD. CONCLUSION: Patients with severe AD demonstrated greater efficacy compared to placebo on measures of cognition and global function.

Deng Y, Sun Y, Shi JJ, Zhang SZ. · West China Hospital, Sichuan University, Chengdu 610041, China. · Yi Chuan. · Pubmed #16606588 No free full text.

Abstract: A C-to-T polymorphism in exon 3 of the low density lipoprotein receptor-related protein 1 (LPR-1) gene has been implicated as a risk factor for Alzheimer's disease (AD). The authors performed a meta-analysis to investigate the association between the C766T polymorphism in the LPR-1 gene and the risk for AD. Nineteen references were retrieved through Medline, Cochran Library and CBM search from 1997 to 2004. Similar search strategies were applied to each of these databases. Studies which were eligible for the meta-analysis should meet the following inclusion criteria: presentation of original data and a cross-sectional design, AD as the outcome of interest, an odds ratio (or enough information to calculate it) reported to quantify the association between the frequencies of genotypes and/or alleles of LPR-1 gene C766T polymorphism and the risk for AD. All analyses were performed with Review Manager 4.2. A total of 3,560 AD patients and 3,476 control subjects were analyzed according to the random effect model because some between-study heterogeneity was found (P<0.01). The combined data statistics revealed that there was no statistical difference (test for overall effect: Z=1.74, P=0.08, OR=1.17, 95% CI: 0.98-1.39; Z=1.31, P=0.19, OR=1.11, 95% CI: 0.95-1.31) in the frequencies of allele and genotype between the AD patients and the controls. The meta-analysis showed that the LPR-1 polymorphism was not a major risk factor for AD, although a small effect of the polymorphism for AD risk could not be excluded.

Bian L, Yang JD, Guo TW, Duan Y, Qin W, Sun Y, Feng GY, He L. · Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; Bio-X Center, Shanghai Jiao Tong University, Shanghai, China. · Biol Psychiatry. · Pubmed #16040006 No free full text.

Abstract: BACKGROUND: Low-density lipoprotein receptor-related protein 1 (LRP1) and alpha-2-macroglobulin (A2M) are two plausible candidate genes for Alzheimer disease (AD) based on their important biological function and positional information. To date, numerous studies have investigated their possible association with AD but the results are controversial. METHODS: To investigate the potential genetic contribution of the two genes in the Han Chinese population, we performed a case-control association study using 10 polymorphisms (4 in LRP1 and 6 in A2M) that span approximately the whole corresponding gene. RESULTS: Comparison of allele, genotype, and haplotype frequencies for polymorphisms in A2M revealed no significant differences between patients and control subjects. For the LRP1 gene, however, we found an overrepresentation of the CTCG haplotype in the control group (p = .002). The difference was still of statistical significance in the apolipoprotein E (APOE) epsilon 4 negative subjects (p(CTCG) = .003). Multiple logistic regression analysis did not show any evidence of synergism between A2M, LRP1, and APOE. CONCLUSIONS: Our results indicate that the CTCG haplotype of LRP1 may reduce the risk of late-onset AD, but A2M is not associated with this disease in the Han Chinese population.

Sun Y, Shi J, Zhang S, Tang M, Han H, Guo Y, Ma C, Liu X, Li T. · Department of Medical Genetics, West China Hospital, Sichuan University and Division of Human Morbid Genomics, State Key Laboratory of Biotherapy of Human Diseases, Chengdu 610041, China. · Neurosci Lett. · Pubmed #15862889 No free full text.

Abstract: In order to clarify the relationship of apolipoprotein CIII (APOC3) polymorphism and sporadic Alzheimer's disease (AD) in Chinese, 165 sporadic AD patients and 174 age-matched elderly individuals were genotyped for the APOC3 SstI and apolipoprotein E (APOE) HhaI polymorphisms. As the result, the APOC3 3017G allele was found to be associated with AD in APOE epsilon4 allele noncarriers (chi2=4.433, P=0.035), and the risk estimate of allele C versus G resulted in an OR of 1.56 (95% CI: 1.03-2.37), although in total no significant differences of allelic or genotypic frequencies between patients and controls were found. Assessment of interaction between APOE epsilon4 and APOC3 3017G status presented an adjusted odds ratio of 0.62 (95% CI: 0.37-1.03) with a borderline significant P-value (P=0.066). Therefore, we conclude that the rare APOC3 G allele may offer some protection against the development of sporadic AD in APOE epsilon4 noncarriers in Chinese.

Shi J, Zhang S, Tang M, Ma C, Zhao J, Li T, Liu X, Sun Y, Guo Y, Han H, Ma Y, Zhao Z. · Department of Medical Genetics, West China Hospital, Sichuan University, Chengdu, 610041, China. · J Gerontol A Biol Sci Med Sci. · Pubmed #15860464 No free full text.

Abstract: Neprilysin has been reported to be a major beta-amyloid peptide (Abeta)-degrading enzyme. The decreased expression and activity of it may contribute to the development of Alzheimer's disease by promoting the accumulation of Abeta. We used denaturing high-performance liquid chromatography to screen the neprilysin gene (NEP) for single nucleotide polymorphisms (SNPs) in 257 Chinese sporadic Alzheimer's disease patients and 242 cognitive normal controls. As a result, eight novel and one known SNP were identified. Three of them, -204G-->C in the promoter region, IVS17-294C-->T, and IVS22+36C-->A showed a significant association with Alzheimer's disease (p = .006,.017, and.003, respectively). Subsequent haplotype analysis provided further evidence of the association (global p < .0001 for the three SNPs mentioned above, and global p < .01 for the eight SNPs with rare allele frequency > 1%). These findings indicate that genetic variations within or extremely close to NEP might influence the susceptibility to Alzheimer's disease in Chinese persons.

Jia J, Xu E, Shao Y, Jia J, Sun Y, Li D. · Department of Neurology, Xuanwu Hospital, Capital University of Medical Sciences, Beijing 100053, China. · J Alzheimers Dis. · Pubmed #15851849 No free full text.

Abstract: This study is to explore whether there is presenilin 1 (PS1) gene mutation in Chinese familial Alzheimer's disease (FAD). There has been no such systemic research before in China. Using polymerase chain reaction, single strand conformation polymorphism (PCR-SSCP), followed by denaturing high performance liquid chromatograph (DHPLC) and DNA sequencing, we analyzed a Chinese family with early onset AD. The patients in this family showed a novel missense mutation in exon 4 of the PS1 gene (G to T change in codon 97), altering valine to leucine acid substitution. Because the change occurred in conserved domains of this gene, and is not present in normal controls, this novel mutation is likely to be causative of Chinese FAD.

Sun Y, Shi JJ, Zhang SZ, Tang MN, Han HY, Guo YB, Ma C, Liu XH, Li T. · Department of Medical Genetics, West China Hospital, Sichuan University, and Division of Human Morbid Genomics, Key Laboratory of Biotherapy of Human Diseases, Ministry of Education, Chengdu 610041,China. · Yi Chuan. · Pubmed #15843343 No free full text.

Abstract: Cathepsin D is the major lysosomal/endosomal aspartic protease and exhibits beta- and gamma-secretase-like activity in vitro. Data from German suggest that the C224T polymorphism in the Cathepsin D gene (CTSD) exon 2 is strongly associated with the risk for Alzheimer's disease (AD).Meanwhile other studies have not been able to replicate the result. It's necessary to determine the genotype of the polymorphism in CTSD in Chinese sporadic AD patients and age-matched controls with normal cognition and examine possible association of the polymorphism with the disease. We find no strong evidence of association between the CTSD C224T polymorphism and Chinese sporadic AD. Whereas there may be a weak synergistic interaction between ApoE epsilon4 and CTSD T allele.

Sun Y, Shi J, Zhang S, Tang M, Liu X, Wang Y, Han H, Guo Y, Deng H, Zhao Z, Ma C. · Department of Medical Genetics, West China Hospital, Sichuan University, Division of Human Morbid Genomics, State Key Laboratory of Biotherapy of Human Diseases, Chengdu, Sichuan, 610041 P. R. China. · Zhonghua Yi Xue Yi Chuan Xue Za Zhi. · Pubmed #15793779 No free full text.

Abstract: OBJECTIVE: Alpha-2 macroglobulin (alpha2M) is a proteinase inhibitor found in association with senile plaques in Alzheimer's disease (AD). Also alpha2M has been implicated in several pathophysiological processes in AD. In view of the recent contradictory reports on the relationship between AD and a common polymorphism I1000V in A2M gene, the present authors studied a relatively large sample, determined the genotype of the I1000V polymorphism in A2M gene in sporadic AD patients and age-matched controls with normal cognition, and examined the possible association of the polymorphism with AD. METHODS: Genotypes of A2M and apolipoprotein E (apoE) were detected by polymerase chain reaction combined with restriction fragment length polymorphism in 257 patients and 242 controls in Guangzhou, and 112 patients and 113 controls in Chengdu. RESULTS: The 1000Val allele frequencies in the merged AD and control groups were 7.7% and 8.7%, respectively. The differences of allelic and genotypic frequencies between the patients and control subjects were not statistically significant, even after stratification by apoE epsilon4 status or by age-of-onset of the disease. CONCLUSION: The results of this study revealed no association between the I1000V polymorphism of A2M and Chinese sporadic AD in Guangzhou and Chengdu.

Bian L, Yang JD, Guo TW, Sun Y, Duan SW, Chen WY, Pan YX, Feng GY, He L. · Institute for Nutritional Sciences, Chinese Academy of Sciences, China. · Neurology. · Pubmed #15277615 No free full text.

Abstract: BACKGROUND: The gene for insulin-degrading enzyme (IDE) represents a strong positional and biologic candidate for late-onset Alzheimer disease (LOAD) susceptibility. IDE is located on chromosome 10q23.3 close to a region of linkage for LOAD. In addition, many studies have identified a possible role of IDE in the degradation of amyloid beta-protein and the intracellular amyloid precursor protein (APP) domain released by gamma-secretase processing. OBJECTIVE: To examine the association of IDE with AD in the Han Chinese. METHODS: Four IDE polymorphisms (three in 5'-untranslated region and one in intron 21) were analyzed, using a population of 210 patients with LOAD and 200 control subjects well matched for age, sex, and ethnic background. RESULTS: Among the four polymorphisms studied, only the C allele of single-nucleotide polymorphism (SNP) IDE2 showed association with AD (p = 0.005). Stratification of the data by APOE epsilon4 status indicated that the association between IDE2 and AD was confined to APOE epsilon4 carriers only. No association was found between all variants studied and AD within APOE epsilon4-negative subjects. The global haplotype frequencies showed significant differences between AD patients and control subjects. Furthermore, overrepresentation of GCTG haplotype in the AD group was found. It may be a risk haplotype for AD. CONCLUSIONS: These results suggest a possible synergic interaction between IDE and APOE epsilon4 in the risk to develop late-onset sporadic AD. IDE might modify the effect of the APOE epsilon4 risk factor in the Han Chinese population.

Sun Y, Du XK, Zhang ZX, Chen X. · Department of Radiology, People's Hospital, Peking University, Beijing 100044, China. · Zhongguo Yi Xue Ke Xue Yuan Xue Bao. · Pubmed #15171548 No free full text.

Abstract: OBJECTIVE: To determine the relationship between the extent of the damage and clinical data in Alzheimer's disease (AD). METHODS: Twenty-two patients with AD and twenty-two controls received MR-diffusion tensor scanning. The fractional anisotropy (FA) values of white matter in AD patients were measured respectively in parietal lobe and the genu of corpus callosum. Independent-samples t-test for non-paired data was used to test differences between AD and controls for FA values. Correlation analysis was applied to reveal the correlations between FA values in each region and the MMSE, FOM, RVR, BD and DS scores. RESULTS: Positive correlations were found between FA values in left parietal lobe and FOM/DS, and between FA values in genu of corpus callosum and MMSE scores. CONCLUSIONS: In AD, the MR-DTI can reflect the relationship between the degree of white matter abnormalities and the cognitive impairment.

Sun Y, Yao J, Kim TW, Tall AR. · Division of Molecular Medicine, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA. · J Biol Chem. · Pubmed #12754201 links to  free full text

Abstract: A hallmark of Alzheimer's disease is the deposition of plaques of amyloid beta peptide (Abeta) in the brain. Abeta is thought to be formed from the amyloid precursor protein (APP) in cholesterol-enriched membrane rafts, and cellular cholesterol depletion decreases Abeta formation. The liver X receptors (LXR) play a key role in regulating genes that control cellular cholesterol efflux and membrane composition and are widely expressed in cells of the central nervous system. We show that treatment of APP-expressing cells with LXR activators reduces the formation of Abeta. LXR activation resulted in increased levels of the ATP-binding cassette transporter A1 (ABCA1) and stearoyl CoA desaturase, and expression of these genes individually decreased formation of Abeta. Expression of ABCA1 led to both decreased beta-cleavage product of APPSw (i.e. C99 peptide) and reduced gamma-secretase-cleavage of C99 peptide. Remarkably, these effects of ABCA1 on APP processing were independent of cellular lipid efflux. LXR and ABCA1-induced changes in membrane lipid organization had favorable effects on processing of APP, suggesting a new approach to the treatment of Alzheimer's disease.

Xu X, Yang D, Wyss-Coray T, Yan J, Gan L, Sun Y, Mucke L. · Gladstone Institute of Neurological Disease, University of California, San Francisco, CA 94141-9100, USA. · Proc Natl Acad Sci U S A. · Pubmed #10377452 links to  free full text

Abstract: Amyloid precursor proteins (APPs) are expressed in multiple organs and cell types in diverse species. Their conservation across species and high abundance in brain and the association of various APP missense mutations with autosomal dominant forms of familial Alzheimer's disease (FAD) suggest important roles for APP in the central nervous system. However, the basic functions of APP in the central nervous system remain largely unknown. To assess potential effects of APP on neuronal death and survival, we transfected APP-deficient rat neuroblastoma cells (B103) with DNA constructs encoding wild-type or FAD-mutant human APP. Wild-type, but not FAD-mutant, APP effectively protected cells against apoptosis induced by ultraviolet irradiation, staurosporine, or p53. Wild-type APP also strongly inhibited p53 DNA-binding activity and p53-mediated gene transactivation, whereas FAD-mutant APP did not. We conclude that APP protects neuronal cells against apoptosis by controlling p53 activation at the post-translational level. Disruption of this function by mutations or alterations in APP processing could enhance neuronal vulnerability to secondary insults and contribute to neuronal degeneration.

Holtzman DM, Bales KR, Wu S, Bhat P, Parsadanian M, Fagan AM, Chang LK, Sun Y, Paul SM. · Department of Neurology, Center for the Study of Nervous System Injury,Washington University School of Medicine, St. Louis, Missouri 63110, USA. · J Clin Invest. · Pubmed #10079115 links to  free full text

Abstract: The epsilon4 allele of apolipoprotein E (apo E) is associated with an increased risk for developing Alzheimer's disease (AD). This may be due to interactions between apo E and the amyloid-beta protein (Abeta). To assess the effects of human apo E isoforms on Abeta deposition in vivo, we bred apo E3 and apo E4 hemizygous (+/-) transgenic mice expressing apo E by astrocytes to mice homozygous (+/+) for a mutant amyloid precursor protein (APPV717F) transgene that develop age-dependent AD neuropathology. All mice were on a mouse apo E null (-/-) background. By nine months of age, APPV717F+/-, apo E-/- mice had developed Abeta deposition, and, as reported previously, the quantity of Abeta deposits was significantly less than that seen in APPV717F+/- mice expressing mouse apo E. In contrast to effects of mouse apo E, similar levels of human apo E3 and apo E4 markedly suppressed early Abeta deposition at nine months of age in APPV717F+/- transgenic mice, even when compared with mice lacking apo E. These findings suggest that human apo E isoforms decrease Abeta aggregation or increase Abeta clearance relative to an environment in which mouse apo E or no apo E is present. The results may have important implications for understanding mechanisms underlying the link between apo E and AD.