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Nipple aspirate fluid (NAF ) refers to the small amount of secretion that is found in breast ducts /lobules of most non -lactating women . This fluid can be collected repeatedly and non -invasively via the nipple using a modified breast pump , and therefore , it is considered to be a potential source for identifying markers of breast cancer . The purpose of this study was to understand factors associated with the ability to secrete fluid and factors associated with the major protein profiles in NAF ; and to identify protein profiles of NAF in a group of healthy non -lactating women who were 30 -40 years old , not pregnant , not breastfeeding , and not taking contraceptive medications . \r \n \r \nAmong 238 women studied , 66 % were secretors of NAF . Using multivariate logistic regression models , higher dietary intake of lactose [Odds Ratio (OR )=2 .7 ; 95 % Confidence Interval (CI ) : 1 .5 -4 .8] , earlier menarche (OR=0 .8 , CI : 0 .7 -1 .0 ) , being parous (OR=2 .3 , CI : 1 .0 -5 .6 ) , and older at first childbirth (OR=1 .5 , CI : 1 .0 -2 .1 ) were found to be independent and positive predictors for being a secretor of NAF . These findings suggest that dietary intake of lactose , a modifiable factor , may be used to change the NAF secretor status of women . \r \n \r \nNAF were analyzed for major proteins . Two major types of protein profiles , type I and type II , were identified . Type I NAF contains proteins found in cystic disease fluid of the breast , whereas type II NAF is enriched in milk -associated proteins . Using multiple logistic regression , type I NAF was predicted independently (P <0 .05 ) by higher body fat mass (Odds Ratio=3 .0 ; CI : 1 .5 -6 .1 ) , more years since last childbirth (OR=2 .6 ; 95 % CI : 1 .3 -5 .2 ) and a higher percentage of calories from saturated fat (OR=4 .1 ; 95 % CI : 1 .1 -14 .6 ) . These results suggest that protein profiles of NAF might be influenced by amounts and /or types of dietary and body fat . \r \n \r \nTwo different analytical strategies , 2D gel analysis coupled with MALDI -TOF /TOF , and 1D gel coupled with LC -MS /MS , were used to characterize protein profiles of type I and II NAF . Using these two strategies , a total of 99 proteins were identified : 13 unique to type I NAF , 57 unique to type II NAF , and 29 common to both types . These strategies will be used to characterize proteins in NAF of breast cancer cases . \r \n |
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