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Articles by S Ahmed
Total Records ( 6 ) for S Ahmed
  L. E Kelemen , X Wang , Z. S Fredericksen , V. S Pankratz , P. D.P Pharoah , S Ahmed , A. M Dunning , D. F Easton , R. A Vierkant , J. R Cerhan , E. L Goode , J. E Olson and F. J. Couch
 

Background: Gene amplification leading to overexpression is a common event in breast tumors that is linked to tumor development and progression. The 17q23 region is amplified in >40% of breast tumors and contains several candidate oncogenes. Because common genetic variation in several oncogenes has been associated with cancer risk, we assessed the relevance of common variants in the 17q23 candidate oncogenes to breast cancer.

Methods: We investigated 60 polymorphisms in the TUBD1, SEPT4, PRKCA, TBX2, TBX4, TEX14, TLK2, YPEL2, and PPM1E genes from this amplicon for association with breast cancer risk among 798 Caucasian breast cancer cases and 843 unaffected Caucasian controls from the Mayo Clinic.

Results: Eight polymorphisms in PRKCA, TBX4, TLK2, and YPEL2 displayed significant dose-response associations with breast cancer risk (Ptrend < 0.05). Of these, PRKCA rs7342847 and TLK2 rs2245092 and rs733025 were also associated with hormone receptor–positive breast cancer: PRKCA rs7342847 (odds ratio, 0.7; 95% confidence interval, 0.6-0.9; Ptrend = 0.002) and TLK2 rs733025 and rs2245092 (both: odds ratio, 0.8; 95% confidence interval, 0.7-1.0; Ptrend = 0.03). Interactions between SEPT4 rs758377 and TEX14 rs302864 (Pinteraction = 0.0003) and between TLK2 rs733025 and YPEL2 rs16943468 (Pinteraction = 0.05) for risk of breast cancer were also observed.

Conclusion: These findings suggest that single polymorphisms and combinations of polymorphisms within candidate oncogenes from the 17q23 amplicon may influence risk of breast cancer overall and possibly specific molecular subtypes of breast tumors. The findings are discussed within the context of the results from two independent data sets. (Cancer Epidemiol Biomarkers Prev 2009;18(6):1864–8)

  K Konishi , L Shen , J Jelinek , Y Watanabe , S Ahmed , K Kaneko , M Kogo , T Takano , M Imawari , S. R Hamilton and J. P. J. Issa
 

Epigenetic changes have been proposed as mediators of the field defect in colorectal carcinogenesis, which has implications for risk assessment and cancer prevention. As a test of this hypothesis, we evaluated the methylation status of eight genes (MINT1, 2, 31, MLH1, p16, p14, MGMT, and ESR1), as well as BRAF and KRAS mutations, in 57 multiple colorectal neoplasias (M-CRN) and compared these to 69 solitary colorectal cancers (S-CRC). There were no significant differences in methylation between M-CRNs and S-CRCs except for p14 and MGMT that was significantly higher in M-CRNs than S-CRCs (16.1% versus 9.3%; 26.5% versus 17.3%, respectively; P < 0.05). We found significant (P < 0.05) correlations for MINT1 (r = 0.8), p16 (r = 0.8), MLH1 (r = 0.9), and MGMT (r = 0.6) methylation between tumors pairs of the same site (proximal/proximal and distal/distal). KRAS showed no concordance in mutations. BRAF mutation showed concordance in proximal site pairs but was discordant in different site pairs. Histologically, eight of 10 paired cancers with similar locations were concordant for a cribriform glandular configuration. We conclude that synchronous colorectal tumors of the same site are highly concordant for methylation of multiple genes, BRAF mutations, and a cribriform glandular configuration, all consistent with a patient-specific predisposition to particular subtypes of colorectal cancers. Screening for and secondary prevention of colon cancer should take this fact into account.

  S. J Woolford , S. J Clark , S Ahmed and M. M. Davis
 

Objective. To assess the feasibility and acceptability of a brief tool to help pediatricians communicate with parents of preschoolers about obesity risk, prevention, and treatment. Methods. The 2-sided Assessment and Targeted Messages (ATM) tool developed by the investigators included sections to assess nutrition and physical activity, self-efficacy and readiness-to-change, obesity-related family history, and treatment/prevention recommendations. Twenty-five pediatricians were recruited to use the ATM and then surveyed regarding their opinions of its feasibility and acceptability. Results. Response rate was 60%. Most ATM features were considered somewhat or very useful by the majority of respondents. The majority of physicians (62%) indicated that they were somewhat likely to use the ATM in the future, with only 23% indicating that they were very likely to use it. The greatest barrier to its use was time. Conclusion. Pediatricians considered the ATM tool moderately feasible and acceptable. Time-efficient methods to help physicians address obesity should be explored.

  R. L Milne , J Benitez , H Nevanlinna , T Heikkinen , K Aittomaki , C Blomqvist , J. I Arias , M. P Zamora , B Burwinkel , C. R Bartram , A Meindl , R. K Schmutzler , A Cox , I Brock , G Elliott , M. W. R Reed , M. C Southey , L Smith , A. B Spurdle , J. L Hopper , F. J Couch , J. E Olson , X Wang , Z Fredericksen , P Schurmann , M Bremer , P Hillemanns , T Dork , P Devilee , C. J van Asperen , R. A. E. M Tollenaar , C Seynaeve , P Hall , K Czene , J Liu , Y Li , S Ahmed , A. M Dunning , M Maranian , P. D. P Pharoah , G Chenevix Trench , J Beesley , kConFab Investigators , N. N Antonenkova , I. V Zalutsky , H Anton Culver , A Ziogas , H Brauch , C Justenhoven , Y. D Ko , S Haas , P. A Fasching , R Strick , A. B Ekici , M. W Beckmann , G. G Giles , G Severi , L Baglietto , D. R English , O Fletcher , N Johnson , I dos Santos Silva , J Peto , C Turnbull , S Hines , A Renwick , N Rahman , B. G Nordestgaard , S. E Bojesen , H Flyger , D Kang , K. Y Yoo , D. Y Noh , A Mannermaa , V Kataja , V. M Kosma , M Garcia Closas , S Chanock , J Lissowska , L. A Brinton , J Chang Claude , S Wang Gohrke , C. Y Shen , H. C Wang , J. C Yu , S. T Chen , M Bermisheva , T Nikolaeva , E Khusnutdinova , M. K Humphreys , J Morrison , R Platte , D. F Easton and on behalf of the Breast Cancer Association Consortium
  Background

A recent genome-wide association study identified single-nucleotide polymorphism (SNP) 2q35-rs13387042 as a marker of susceptibility to estrogen receptor (ER)–positive breast cancer. We attempted to confirm this association using the Breast Cancer Association Consortium.

Methods

2q35-rs13387042 SNP was genotyped for 31 510 women with invasive breast cancer, 1101 women with ductal carcinoma in situ, and 35 969 female control subjects from 25 studies. Odds ratios (ORs) were estimated by logistic regression, adjusted for study. Heterogeneity in odds ratios by each of age, ethnicity, and study was assessed by fitting interaction terms. Heterogeneity by each of invasiveness, family history, bilaterality, and hormone receptor status was assessed by subclassifying case patients and applying polytomous logistic regression. All statistical tests were two-sided.

Results

We found strong evidence of association between rs13387042 and breast cancer in white women of European origin (per-allele OR = 1.12, 95% confidence interval [CI] = 1.09 to 1.15; Ptrend = 1.0 x 10–19). The odds ratio was lower than that previously reported (P = .02) and did not vary by age or ethnicity (all P ≥ .2). However, it was higher when the analysis was restricted to case patients who were selected for a strong family history (P = .02). An association was observed for both ER-positive (OR = 1.14, 95% CI = 1.10 to 1.17; P = 10–15) and ER-negative disease (OR = 1.10, 95% CI = 1.04 to 1.15; P = .0003) and both progesterone receptor (PR)–positive (OR = 1.15, 95% CI = 1.11 to 1.19; P = 5 x 10–14) and PR-negative disease (OR = 1.10, 95% CI = 1.06 to 1.15; P = .00002).

Conclusion

The rs13387042 is associated with both ER-positive and ER-negative breast cancer in European women.

  R. E Rosenberg , A. N. U Ahmed , S. K Saha , M. A Chowdhury , S Ahmed , P. A Law , R. E Black , M Santosham and G. L. Darmstadt
 

Sepsis is a leading cause of mortality for neonates in developing countries; however, little research has focused on clinical predictors of nosocomial infection of preterm neonates in the low-resource setting. We sought to validate the only existing feasible score introduced by Singh et al. in 2003 and to create an improved score. In a secondary analysis of daily evaluations of 497 neonates ≤33 weeks gestational age admitted to a tertiary care NICU in Dhaka, Bangladesh, we tested the Singh score and then constructed and internally validated our own bedside predictive score. The Singh score had low sensitivity of 56.6% but good positive predictive value (PPV) of 78.1% in our sample. Our five-sign model requiring at least one clinical sign of infection (apnea, hepatomegaly, jaundice, lethargy and pallor) had an area under the receiver operating characteristic of 0.70, sensitivity of 77.1%, and PPV of 64.9%. Our clinical sepsis score is the first bedside clinical screen exclusively for hospitalized, very premature neonates in a low-resource setting, and warrants external validation.

  S. M Chacko , S Ahmed , K Selvendiran , M. L Kuppusamy , M Khan and P. Kuppusamy
 

Stem cells transplanted to the ischemic myocardium usually encounter massive cell death within a few days of therapy. Hypoxic preconditioning (HPC) is currently employed as a strategy to prepare stem cells for increased survival and engraftment in the heart. However, HPC of stem cells has provided varying results, supposedly due to the differences in the oxygen concentration, duration of exposure, and passage conditions. In the present study, we determined the effect of HPC on rat mesenchymal stem cells (MSCs) exposed to 0.5% oxygen concentration for 24, 48, or 72 h. We evaluated the expression of prosurvival, proangiogenic, and functional markers such as hypoxia-inducible factor-1, VEGF, phosphorylated Akt, survivin, p21, cytochrome c, caspase-3, caspase-7, CXCR4, and c-Met. MSCs exposed to 24-h hypoxia showed reduced apoptosis on being subjected to severe hypoxic conditions. They also had significantly higher levels of prosurvival, proangiogenic, and prodifferentiation proteins when compared with longer exposure (72 h). Cells taken directly from the cryopreserved state did not respond effectively to the 24-h HPC as those that were cultured under normoxia before HPC. Cells cultured under normoxia before HPC showed decreased apoptosis, enhanced expression of connexin-43, cardiac myosin heavy chain, and CD31. The preconditioned cells were able to differentiate into the cardiovascular lineage. The results suggest that MSCs cultured under normoxia before 24-h HPC are in a state of optimal expression of prosurvival, proangiogenic, and functional proteins that may increase the survival and engraftment in the infarct heart. These results could provide further insights into optimal preparation of MSCs which would greatly influence the effectiveness of cell therapy in vivo.

 
 
 
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