Conditioned media of mouse macrophages modulates neuronal dynamics in mouse hippocampal cells.

Many neurodegenerative diseases display both neuroinflammation and impaired neuron production in hippocampus. Although immunotherapeutic strategies indicate a promising avenue for combating neuroinflammation-induced diseases, directly targeting microglia, principle immune cells of CNS for such therapeutic purposes might be problematic due to invasive procedures. Instructing monocytes/macrophages from the periphery can be a less invasive and advantageous strategy compared to reaching microglia. But interplay between CNS neurons and macrophages even under normal conditions is poorly understood. To explore the experimental platform of how CNS derived neuronal cells respond to overall soluble factors of a non-CNS derived immune cell type, we introduced the conditioned media (CM) of unstimulated, and lipopolysaccharide stimulated RAW264.7 mouse macrophages to immortalized HT-22 mouse hippocampal cells during and after they were exposed to neuronal differentiation media. First, we recorded the cell viability of HT-22 cell study groups by using a real time cell analyzer. Then, we assessed the immunocytochemical expression of CR and CB proteins and mRNA levels of Ascl1, Bdnf, CB, Grn, Nrf2 and Rac1 genes via semi quantitative image analysis and q-RT-PCR among the different groups of HT-22 cells. Real time cell monitoring provided a solid physiological evidence regarding how various cell culture treatments affected the cell viability of HT-22 cells over time. Our further findings suggested that culturing HT-22 cells with unstimulated CM of macrophages markedly increased the immunocytochemical expression of CR and mRNA expression of Ascl1, Bdnf, CB and Grn genes, while the latter media resulted in decreases of those expressions. Overall, our results imply that HT-22 cells are meaningfully responsive to the secretome of RAW264.7 macrophages and using the interaction of macrophage with CNS derived neuronal cells is an instructive platform for deciphering the molecular mechanisms of cellular communication between immune system cells and neurons.

Non-Destructive Removal of Dental Implant by Using the Cryogenic Method.

Background and Objectives: The gold standard for a successful prosthetic approach is the osseointegration of an implant. However, this integration can be a problem in cases where the implant needs to be removed. Removing the implant with minimal damage to the surrounding tissues is important. Osteocytes cannot survive below −2 °C, but epithelial cells, fibroblasts, and other surrounding tissue cells can. Remodeling can be triggered by cryotherapy at temperatures that specifically affect osteocyte necrosis. In this study, we aimed to develop a method for reversing the osseointegration mechanism and for protecting the surrounding tissues by bone remodeling induced by CO2 cryotherapy. Materials and Methods: In this study, eight 2.8 mm diameter, one-piece mini implants were used in New Zealand rabbit tibias. Two control and six implants were tested in this study. After 2 months of osseointegration, a reverse torque force method was used to remove all osseointegrated implants at 5, 10, 20, and 30 Ncm. The osseointegration of the implants was proven by periotest measurements. Changes in bone tissue were examined in histological sections stained with toluidine blue after rabbit sacrifice. The number of lacunae with osteocyte, empty lacunae, and lacunae greater than 5 µm and the osteon number in a 10,000 µm2 area were calculated. Cryotherapy was applied to the test implants for 1 min, 2 min, and 5 min. Three implants were subjected to cryotherapy at −40 °C, and the other implants were subjected to cryotherapy at −80 °C. Results: Empty lacunae, filled osteocytes, lacunae >5 µm, and the osteon count around the implant applied at −40 °C were not significantly different from the control implants. The application of −40 °C for 1 min was found to cause minimal damage to the bone cells. The implants, which were applied for 1 min and 2 min, were successfully explanted on the 2nd day with the 5 Ncm reverse torque method. Test implants, which were applied cold for 5 min, were explanted on day 1. Tissue damage was detected in all test groups at −80 °C. Conclusions: The method of removing implants with cryotherapy was found to be successful in −40 °C freeze−thaw cycles applied three times for 1 min. To prove implant removal with cryotherapy, more implant trials should be conducted.

The roles of ANRIL polymorphisms in periodontitis: a systematic review and meta-analysis.

OBJECTIVES: The aim of this study is to investigate the potential role of ANRIL polymorphisms in susceptibility to periodontitis. METHODS: The authors searched Pubmed, Web of Science, and Scopus up to April 2021 to identify all published studies without any language restriction on the association between ANRIL and periodontitis. A meta-analysis of all ANRIL variants replicated by three or more studies was performed by testing multiple genetic models of association. Pooled odds ratios and 95% confidence intervals (CI) were used to estimate associations. Tests for sensitivity and publication bias were performed. RESULTS: Twenty-two variants in the ANRIL gene were examined for their potential association with the risk of periodontitis. However, only 4 (rs1333048, rs1333042, rs2891168, rs496892) are replicated at least three or more studies. The ANRIL rs1333048 was the most replicated polymorphisms with five articles, seven different populations comprising of 1331 cases, and 2624 controls. The pooled overall analysis showed that rs1333048, rs1333042, rs2891168, and rs496892 polymorphisms were associated with susceptibility to periodontitis in the whole population in allele contrast and dominant models. Moreover, similar to the overall analysis, rs1333048 polymorphism showed a significant association with grade C periodontitis (known as aggressive periodontitis in 1999 classification) in allele contrast (OR = 1.16) and dominant models (1.19). Interestingly, subgroup analysis also showed rs1333048 polymorphism might influence predisposition to a slowly progressive form of periodontitis (known as chronic periodontitis in 1999 classification). CONCLUSION: Our findings suggest that the ANRIL rs1333048, rs1333042, rs2891168, and rs496892 polymorphisms might influence predisposition to periodontitis, particularly in Caucasians. CLINICAL SIGNIFICANCE: ANRIL gene may represent a potential risk marker for periodontitis.

Periodontal Treatment Is Associated With Improvement in Gastric Helicobacter pylori Eradication: An Updated Meta-analysis of Clinical Trials.

OBJECTIVES: The efficacy of conventional systemic antibiotic therapy for eradication of Helicobacter pylori has been seriously challenged by antibiotic resistance. Identification of alternative therapeutic strategies might help to overcome this limitation. The aim of this study was to update previous meta-analyses that investigated the effect of periodontal treatment on gastric H. pylori eradication. METHODS: A systematic electronic search of the literature was conducted to identify all published clinical trials that compared the effect of adjunct periodontal treatment on conventional systemic H. pylori eradication therapy. RESULTS: The updated analysis (consisting of 541 participants representing six studies) demonstrated that, compared with conventional systemic eradication therapy alone, the addition of periodontal treatment resulted in improvements in gastric H. pylori eradication rates with OR 4.11 (P = 0.01). Moreover, not to lose any data, the previously presented Chinese results that could not be assessed by any available mechanism deduced from previously published meta-analysis and with other records were re-analysed. Similarly, the second meta-analysis adding up to a final cluster of 10 studies (909 participants) gives further credence to periodontal treatment as a useful concomitant therapy in the H. pylori eradication therapy (odds ratio [OR] = 2.65; P = 0.0002). Finally, the meta-analysis of four trials consisting of 177 cases and 161 controls showed that periodontal treatment also improved non-recurrence rates of gastric H. pylori infection, with an OR of 5.36 (P-value = 0.0002). CONCLUSION: Although the inclusion of five additional clinical trials in this updated meta-analysis has not changed the result of the previous review, the current meta-analysis is superior for having removed one study involving the use of chlorhexidine, which did not meet appropriate criteria for inclusion. Our results strengthen the value of periodontal treatment as an adjunctive remedy. Consistency of these results suggests that the incorporation of professional periodontal treatment with systemic eradication therapy may be a wise strategy, enhancing the efficacy of H. pylori eradication therapy. Systematic review registration: in PROSPERO ID number: CRD42019119347.

Comparison of gingival crevicular fluid and serum human beta-defensin-2 levels between periodontal health and disease.

BACKGROUND: The aim of this study was to evaluate the levels of serum and gingival crevicular fluid (GCF) human beta-defensin-2 (hBD-2), an antimicrobial peptide that takes roles in inflammatory diseases, in patients with chronic periodontitis (CP). SUBJECTS AND METHODS: A total of one hundred and one individuals, 59 controls and 42 patients with CP, participated in this study. Clinical index measurements were recorded during the periodontal examination, and radiographic evaluation was also performed. The serum and gingival crevicular fluid (GCF) samples were taken from all of the participants, and the hBD-2 levels were determined biochemically by enzyme-linked immunosorbent assay (ELISA). RESULTS: In our study, hBD-2 GCF levels in CP (stages II-IV periodontitis based on the new 2018 classification of periodontal diseases) group (2.77 ng/30 s) were higher than in the periodontally healthy (2.51 ng/30 s; p = .047) individuals. In contrast, serum hBD-2 levels in CP (2.92 ng/ml) were lower compared with those in healthy controls (7.75 ng/ml, p < .001). CONCLUSION: Interestingly, our results showed that while higher hBD-2 GCF levels are associated with CP, lower serum hBD-2 levels were detected in CP.

Serum vitamin D concentration is associated with antimicrobial peptide level in periodontal diseases.

OBJECTIVE: The aim of the study was to assess whether or not Vitamin D deficiency was associated with the GCF and gingival tissue antimicrobial peptides (AMP), namely, human beta defensin-2 (hBD-2) and cathelicidin (LL-37) level in chronic periodontitis (CP) and gingivitis patients. DESIGN: A total of 80 volunteers were included in this study. Forty was classified as Vitamin D deficient (25(OH)D <20 ng/mL), and 40 Vitamin D sufficient patients (25(OH)D ≥ 20 ng/mL). Of these, 20 of them were affected by gingivitis and 20 by CP. Following sampling, the hBD-2 and LL-37 concentration in gingival tissues and GCF were determined by the ELISA method. RESULTS: The hBD-2 and LL-37 levels were higher in periodontitis compared to gingivitis patients within Vitamin D sufficient and deficient groups. The AMP levels of GCF and gingival tissue in the vitamin D deficient group was lower compared to sufficient serum 25(OH)D within gingivitis and CP groups. Additionally, a non-parametric regression model known as the generalized additive model was used to identify the contribution of diagnosis, Vitamin D status, and other potential clinical variables on the local levels of AMPs. Regression analysis showed that the periodontal disease status, serum vitamin D concentration were independent predictors for elevated GCF AMP levels. Finally, a positive correlation between GCF and tissue levels of both hBD-2 (r = 0.82; <0.0001) and LL-37 (r = 0.65; <0.0001) was detected. CONCLUSION: This study shows that serum 25(OH)D deficiency is associated with decreased hBD-2 and LL-37 expression of GCF and gingival tissues in both gingivitis and CP patients.

DEFB4A Promoter Polymorphism Is Associated with Chronic Periodontitis: A Case-Control Study.

Background: Human ß-defensin-2 is an antimicrobial peptide with antibiotic properties secreted by the oral cavity to protect the host against microbial attack. The inter-individual differences in defensin expression profiles due to genetic variation might be partly responsible for differences in disease susceptibility. Aims: The objective of this study was to examine whether variation in the human ß-defensin-2 gene (DEFB4A) is associated with chronic periodontitis (CP). Materials and Methods: This case-control study used Sanger sequencing to analyze two promoter polymorphisms of the DEFB4A gene with potential functional consequences using DNA samples collected from 200 unrelated individuals. Results: The DEFB4A rs1339258595 promoter polymorphism is associated with CP risk and clinical attachment level (CAL) but the rs3762040 polymorphism is not. Carriers of the T allele (rs1339258595) were approximately three times less likely to develop periodontitis compared with noncarriers (p = 0.0004, odds ratio = 0.35). Consistent with a protective role, the carriers of T allele had a lower CAL compared with the wild-type (G) allele. Moreover, the wild-type diplotype (GGGG) had a significantly higher risk of tooth loss compared with other diplotypes (p = 0.016). Conclusion: This study demonstrates that genetic variation in the promoter region of DEFB4A likely affects resistance to periodontal infection and might be a potential marker for CP risk and severity.

Periodontal treatment is more effective in gastric Helicobacter pylori eradication in those patients who maintain good oral hygiene.

OBJECTIVES: This study aimed to investigate the effect of periodontal treatment and oral hygiene on the eradication of gastric Helicobacter pylori. MATERIALS AND METHODS: In this clinical trial, the 98 patients with gastric H. pylori infection that were enrolled received either triple-therapy regimen only or triple-therapy regimen plus periodontal treatment given during triple therapy. Eradication of H. pylori was checked at 3 months, and then after therapy using the urea breath test. RESULTS: The triple-therapy plus periodontal treatment regime resulted in a 64.7% eradication rate, and the triple-therapy regime alone resulted in a 51.1% eradication rate (P = 0.17). Additionally, subgroup analysis indicated that the beneficial effect of periodontal treatment on the gastric H. pylori eradication rate improved if adequate plaque control was maintained (P = 0.02). Multivariate logistic regression analysis showed that post-treatment oral hygiene status [as indicated by the Oral Hygiene Index (OHI)] was associated with H. pylori eradication (P = 0.02), but not with pretreatment oral hygiene status (P = 0.24). Oral hygiene measures without periodontal treatment appear to have a limited impact on H. pylori eradication. Post-treatment oral hygiene level (OHI ≤ 1.25) had a positive effect on H. pylori eradication, increased the gastric eradication rate, with an OR of 3.19, and the oral H. pylori eradication rate, with an OR of 4.57. Furthermore, if periodontal treatment was unsuccessful in eliminating oral H. pylori, as tested using the Campylobacter-like organism test, the OR for the unsuccessful gastric eradication increased 64-fold. Conclusion This result illustrates that the key factors for achieving successful gastric H. pylori eradication are professional periodontal treatment and the patients' later adherence to an oral hygiene regimen.

Evaluation of the Rho A/Rho-kinase pathway in the uterus of the rat model of polycystic ovary syndrome.

The aim of this study was to investigate the expression of RhoA/Rho-kinase in the uterus and the effect of Rho-kinase inhibitors on uterine contractions of dehydroepiandrosterone (DHEA) induced polycystic ovary syndrome (PCOS) rats. Forty-four female Sprague-Dawley (21 days old) rats divided into three groups: The control group (n = 14, any procedure was not performed), vehicle group (n = 14, 0.2 ml of sesame oil, subcutaneous injection, 20 days) and PCOS group (n = 16, DHEA 6 mg/100 g in 0.2 ml of sesame oil, subcutaneous injection, 20 days). The myometrium thickness and uterine wet weight were assessed. The mRNA and protein expressions of Rho A, the effect of Rho-kinase inhibitors (fasudil and Y-27632) on KCl, carbachol, and PGF2α induced contractions were evaluated in the uterus. In the PCOS group, the myometrium thickness and uterine wet weight significantly increased compared to the control group and vehicle group. The mRNA expression level and the immunoreactive score of Rho A, ROCK 1, ROCK 2 were similar in all groups. In the PCOS group, KCl, carbachol, and PGF2α induced uterine contractions significantly increased compared to the control group and vehicle group. Fasudil and Y-27632 significantly inhibited KCl, carbachol, and PGF2α induced uterine contractions in all groups. In conclusion, the expression of Rho A, ROCK 1, ROCK 2 not changed although myometrium thickness, uterine wet weight and the contractile responses of uterus increased in the PCOS group. The results suggest that the Rho-kinase inhibitors effectively suppressed increased contractions in the PCOS group they might be potential therapeutic agents.

Vitamin D deficiency in patients with aggressive periodontitis.

OBJECTIVES: Vitamin D deficiency is a frequent health problem worldwide, especially as fewer people spend much time in the sun. Vitamin D deficiency is linked to several infectious and inflammatory conditions, including periodontal disease. However, its role in aggressive periodontitis (AgP) has not been well studied. We evaluated the association between vitamin D concentration and periodontal disease, both AgP and chronic (CP) periodontitis. METHOD AND MATERIALS: Forty-seven AgP 55 CP and 27 control subjects participated. All patients were tested for serum vitamin D concentration (25(OH)D), parathyroid hormone, and serum bone-related biomarkers (alkaline phosphatases, calcium, and phosphorus) regulated by vitamin D. RESULTS: The patients with AgP had lower serum 25(OH)D concentration (11.22 ± 4.8 ng/ml) than controls (16.9 ± 6.4 ng/ml) and patients with CP (16.13 ± 8.3 ng/ml; overall p value 0.0002). These associations remained significant after adjustment for age and gender (p = 0.002). No significant differences were observed in any bone-related biomarker among the three groups, and no association was observed with periodontal disease indices. CONCLUSIONS: Our results suggest that vitamin D deficiency may be a potential risk factor for AgP. Given the high prevalence of vitamin D deficiency in AgP patients, routine screening for vitamin D status may be advisable in these subjects.

The relationship of periodontal disease severity to serum and GCF substance P levels in diabetics.

OBJECTIVE: To compare circulating and gingival crevicular fluid (GCF) substance P concentrations in well- and poorly controlled type 2 diabetic patients with chronic periodontitis. METHOD AND MATERIALS: Forty-five serum and 90 GCF samples were collected from diabetic patients with periodontal disease, and the concentrations of substance P were quantified by radioimmunoassay. RESULTS: Serum substance P levels were higher in the poorly controlled diabetic group than in patients with good glycemic control (P = .01); within the poorly controlled group, patients with severe attachment levels had the highest circulating substance P levels (P = .02). Additionally, the diseased sites showed higher substance P levels than control sites (P = .0016). The GCF substance P concentrations in diseased sites correlated significantly with clinical findings such as Plaque Index (r = 0.51, P = .001) and bleeding on probing (r = 0.35, P = .029). CONCLUSION: Within the limits of this study, our preliminary findings indicate that periodontal inflammation may influence circulating and GCF substance P levels in poorly controlled diabetic subjects.

Position and course of the mandibular canal in skulls.

OBJECTIVE: The aim of this study was to examine and describe the topography of the mandibular canal (MC) in both vertical and occlusal dimensions. STUDY DESIGN: Fifty-two adult skulls deposited in the University of Pittsburgh School of Dental Medicine skull collection were evaluated in this study. Cone-beam computerized tomographic scans of each skull were obtained. RESULTS: The vertical course of MC was classified into 3 types: straight projection (12.2%), catenary-like configuration (51.1%), and progressive descent from posterior to anterior (36.7%). The evaluation of the buccolingual dimension showed that the mandibular canal was located either in contact with or close to the lingual cortical plate (≤ 2 mm) in the molar region of the majority of the cases. As it proceeds anteriorly it moves toward the buccal aspect of the mandible, where it finally emerges through the mental foramen. Three emerging patterns of mandibular canal were observed: sharp turn (53.2%), soft curved exit (28.8%), and straight path (17.4%). The examination of the vertical dimension showed that the canal was located almost 1 cm above the inferior border of the mandible and then ascended to reach the mental foramen, which is located ~16 mm (range 13.4-20.3 mm) above the inferior border of the mandible. We found a strong correlation between height of the mandible and location of the mental foramen (r = 0.64; P < .0001). CONCLUSIONS: The course of mandibular canal described in vertical and axial dimensions and variation in its path have been classified. In addition to variation in location of MC, it has different anatomic configurations which clinicians should be familiar with in any surgical procedures involving the posterior mandible.

TLR4 as a risk factor for periodontal disease: a reappraisal.

AIM: To determine whether genetic variants of the TLR4 gene are associated with either chronic or aggressive periodontitis. METHODS: A systematic electronic search of literature was conducted to identify all published studies without any language restriction on the association between TLR4 and periodontal diseases, including chronic periodontitis and aggressive periodontitis. All case-control studies evaluating the TLR4 Asp299Gly and Thr399Ile polymorphisms in chronic or aggressive periodontitis were identified. A meta-analysis of the studies that fulfilled the inclusion criteria was performed. RESULTS: Seven studies comprising 744 chronic periodontitis cases and 855 controls and four studies consisting of a total of 295 aggressive periodontitis cases and 456 controls were included in the meta-analysis. In the pooled analysis, the TLR4 299Gly allele (TLR4+896 A>G) appeared to be a genetic risk factor for susceptibility to chronic periodontitis with a random effects and fixed effects odds ratio (OR) of 1.43 [95% confidence interval (CI):1.04-1.97; p=0.03]. On the other hand, the TLR4 399Ile polymorphism (TLR4+1196 C>T) showed a protective effect against aggressive periodontitis with a random effects OR of 0.29 (95% CI: 0.13-0.61; p=0.001). CONCLUSION: Our results suggest that the alleles 299Gly and 399Ile in TLR4 can be a potential genetic marker for periodontal disease.

Association of tagSNPs in the urokinase-plasminogen activator (PLAU) gene with Alzheimer's disease and associated quantitative traits.

The gene coding for urokinase-plasminogen activator (PLAU) is a strong biological and positional candidate gene for Alzheimer's disease (AD). Previously some studies have examined the role of common variation in the PLAU gene with AD risk but the results have been inconsistent and this inconsistency could have been due to the use of relatively small sample sizes. In this study we evaluated the distribution of four tagSNPs (rs2227562 in intron 5, rs2227564 in exon 6, rs2227571 in intron 9, and rs4065 in 3'UTR) in the PLAU gene in a large case-control study consisting of up to 1,000 AD patients and 697 white control subjects. We examined the role of these tagSNPs with AD risk and quantitative traits of AD, including age-at-onset (AAO), disease duration, and mini-mental state examination (MMSE) scores. The 3'UTR SNP revealed modest significant association with risk (OR = 0.71, 95% CI: 0.53-0.95; P = 0.02), AAO (P = 0.036) and disease duration (P = 0.04) of AD. In addition, the intron 9 SNP also revealed a significant association with AAO (P = 0.01) and disease duration (P = 0.006). Our data on a large number of AD cases and controls suggest that genetic variation in PLAU may affect the risk and AAO of AD.

Lack of association of 5 SNPs in the vicinity of the insulin-degrading enzyme (IDE) gene with late-onset Alzheimer's disease.

Insulin-degrading enzyme (IDE) is a strong biological and positional candidate gene for Alzheimer's disease (AD). Previously some studies have examined the role of common variation in the IDE gene with AD risk but the results have been inconsistent. In this study we examined the role of 5 SNPs that define a linkage disequilibrium (LD) block spanning 276kb around IDE. Our sample comprised up to 1012 late-onset AD (LOAD) cases and 771 older white controls. In addition, we also examined the association of these SNPs with quantitative measures of AD progression, namely age-at-onset (AAO), disease duration and Mini-Mental State Examination (MMSE) score. None of the SNPs examined in this fairly large case-control sample revealed significant association with AD risk. These SNPs also showed no significant association with AD quantitative traits.

Alpha-1-antichymotrypsin (ACT or SERPINA3) polymorphism may affect age-at-onset and disease duration of Alzheimer's disease.

In addition to genetic effects on disease risk, age-at-onset (AAO) of Alzheimer's disease (AD) is also genetically controlled. Using AAO as a covariate, a linkage signal for AD has been detected on chromosome 14q32 near the alpha1-antichymotrypsin (ACT) gene. Previously, a signal peptide polymorphism (codon -17A>T) in the ACT gene has been suggested to affect AD risk, but with inconsistent findings. Given that a linkage signal for AAO has been detected near ACT, we hypothesized that ACT genetic variation affects AAO rather than disease risk and this may explain the previous inconsistent findings between ACT genetic variation and AD risk. We examined the impact of the ACT signal peptide polymorphism on mean AAO in 909 AD cases. The ACT polymorphism was significantly associated with AAO and this effect was independent of the APOE polymorphism. Mean AAO among ACT/AA homozygotes was significantly lower than that in the combined AT+TT genotype group (p = 0.019) and this difference was confined to male AD patients (p = 0.002). Among male AD patients, the ACT/AA genotype was also associated with shorter disease duration before death as compared to the ACT/AT+TT genotypes (p = 0.012). These data suggest that the ACT gene may affect AAO and disease duration of AD.

Genetic variation in the choline acetyltransferase (CHAT) gene may be associated with the risk of Alzheimer's disease.

Several independent linkage studies have mapped a broad susceptibility region for Alzheimer's disease (AD) on the long arm of chromosome 10. There are several biological candidate genes in this region, including choline acetyltransferase (CHAT). A number of studies have examined the role of CHAT genetic variants with AD risk and age-at-onset (AAO), but the results are equivocal. We examined the association of three Single Nucleotide Polymorphisms (SNPs) in the CHAT gene in 1001 white sporadic late-onset AD (LOAD) cases and 708 white controls. We also examined the role of these three SNP with quantitative traits of AD including AAO, disease duration, and Mini-Mental State Examination (MMSE) score. We observed both allelic and genotypic associations of the intron 9 SNP with AD risk in the total sample (p = 0.029 for genotype and p = 0.028 for allele frequency differences) as well as among non-APOE*4 carriers (p = 0.007 for genotype and p = 0.006 for allele frequency differences). Three-site haplotype analysis confirmed that haplotypes determined by the intron 9 SNP were associated with either risk (p = 0.0009) or protective (p = 0.0082) effects among non-APOE*4 carriers. The three CHAT SNPs also showed a modest association with MMSE score. Our data suggest that genetic variation in the CHAT gene may be associated with AD risk and quantitative traits related to AD.

Three SNPs in the GSTO1, GSTO2 and PRSS11 genes on chromosome 10 are not associated with age-at-onset of Alzheimer's disease.

Linkage studies suggest the presence of putative risk and/or age-at-onset genes for Alzheimer's disease on Chromosome 10. Recently, a genomic converging approach using a combination of linkage, expression and association studies has reported significant associations of the glutathione S-transferase omega 1 and 2 (GSTO1 and GSTO2) genes and possibly the protease serine 11 (PRSS11) gene on chromosome 10 with age-at-onset, but not risk, for Alzheimer's disease (AD) and Parkinson disease. We investigated the association of the reported three polymorphisms in 990 sporadic late-onset AD cases (26% autopsy confirmed) and 735 controls. In our sample, we found no association either with age-at-onset in AD cases or with disease risk in the case-control cohort. However, haplotype analysis revealed a modest association of one haplotype with AD risk (p = 0.04). Additional markers in these genes need to be screened to explore their role in the etiology of AD.