Kinetic Exclusion Assay of Biomolecules by Aptamer Capture.

DNA aptamers are short nucleotide oligomers selected to bind a target ligand with affinity and specificity rivaling that of antibodies. These remarkable features recommend aptamers as candidates for analytical and therapeutic applications that traditionally use antibodies as biorecognition elements. Numerous traditional and emerging analytical techniques have been proposed and successfully implemented to utilize aptamers for sensing purposes. In this work, we exploited the analytical capabilities offered by the kinetic exclusion assay technology to measure the affinity of fluorescent aptamers for their thrombin target and quantify the concentration of analyte in solution. Standard binding curves constructed by using equilibrated mixtures of aptamers titrated with thrombin were fitted with a 1:1 binding model and provided an effective Kd of the binding in the sub-nanomolar range. However, our experimental results suggest that this simple model does not satisfactorily describe the binding process; therefore, the possibility that the aptamer is composed of a mixture of two or more distinct Kd populations is discussed. The same standard curves, together with a four-parameter logistic equation, were used to determine "unknown" concentrations of thrombin in mock samples. The ability to identify and characterize complex binding stoichiometry, together with the determination of target analyte concentrations in the pM-nM range, supports the adoption of this technology for kinetics, equilibrium, and analytical purposes by employing aptamers as biorecognition elements.

Impact of race and ethnicity on outcomes for estrogen receptor-negative breast cancers: experience of an academic center with a charity hospital.

BACKGROUND: African American women have a higher breast cancer mortality rate than Caucasian women. Estrogen receptor (ER)-negative tumors, which are more aggressive than ER-positive tumors, occur more frequently in African American women than in Caucasian women and may contribute to apparent disparities in outcomes. However, outcome results need to be controlled for socioeconomic status (SES). We evaluated the effect of race and ethnicity on outcomes of patients with ER-negative tumors by determining outcomes in African American and Caucasian women with low SES but similar access to care. STUDY DESIGN: From a prospective database of 786 patients with stage 0 to III breast cancer, all 375 patients with ER-negative tumors were evaluated. Patients received standard definitive operations and adjuvant treatment. Compliance with treatment was more than 90%. Primary endpoints were cancer recurrence and overall survival (OS). Statistical analysis performed included Kaplan-Meier survival analysis, log-rank test, Cox proportional hazard model, Student's t-test, and chi-squared test. A p value < or = 0.05 was considered statistically significant. RESULTS: Fifty-four percent of African American patients had ER-negative tumors versus 39% in Caucasian patients. In both groups, 69% of patients received free care or Medicaid, with a median income of $16,577 (range $15,367 to $36,788). Comparing the 2 racial and ethnic groups, mean tumor size (p = 0.19), tumor grade distribution (p = 0.32), nodal distribution (p = 0.50), stage distribution (p = 0.30), rate of mastectomy (p = 0.47), receipt of adjuvant chemotherapy (p = 0.07), and financial class distribution (p = 0.67) were not significantly different. The 5-year OS was 77% for both groups (p = 0.59). On multivariate analysis, race and ethnicity were not independent predictors of OS (p = 0.73). CONCLUSIONS: In a predominantly indigent population, race and ethnicity had no impact on outcomes for ER-negative breast cancer.

Race/Ethnicity has no effect on outcome for breast cancer patients treated at an academic center with a public hospital.

BACKGROUND: African American women have a higher breast cancer mortality rate than Caucasian women. To understand this difference, socioeconomic status (SES) needs to be controlled, which can be achieved by evaluating outcome within a population that is underinsured or low SES. We elected to examine the effect of race/ethnicity on outcome of patients with operable breast cancer by evaluating outcome in a population with low SES and similar access to care. METHODS: From a prospective breast cancer database created in 1998, we examined outcome for 786 patients with stage 0 to III breast cancer treated up to September 2008. Patients were treated at Louisiana State University Health Sciences Center in Shreveport and E.A. Conway Hospital and the majority received standard definitive surgery as well as appropriate adjuvant treatment. Primary endpoints were cancer recurrence and death. Statistical analysis performed included Kaplan-Meier survival analysis, log-rank test, Cox proportional hazards model, independent-samples t test, and chi(2) test. P

Chiral base-mediated benzylic functionalisation of tricarbonylchromium(0) complexes of benzylamine derivatives.

The novel complex (eta 6-benzylamine)tricarbonylchromium(0) 11 was prepared in up to 66% yield by direct complexation with Cr(CO)6 in refluxing 1,4-dioxane. Imine derivatives of this complex were readily deprotonated at the benzylic position by diamide 5, and the resultant anions reacted regioselectively with electrophiles (Me3SiCl or MeI) to give fairly good yields of products substituted at the benzylic carbon. Products of up to 87% e.e. were obtained in these reactions, with the highest enantioselectivity being derived from the tert-butyl-substituted imine complex 25.

Structural features of bovine caseinomacropeptide A and B by 1H nuclear magnetic resonance spectroscopy.

Samples of bovine caseinomacropeptide (CMP) were isolated from kappa-casein A and kappa-casein B and fractionated to give aglycosylated CMP A and CMP B and monoglycosylated CMP A. The secondary structures of these three peptides were compared under neutral and acidic (pH 4.2) conditions, using two-dimensional (2D) 1H nuclear magnetic resonance (NMR) spectroscopy. The differences between the spectra at pH 4.2 and 7.0 and the spectra of the aglycosylated and glycosylated CMP A were subtle, indicating little change in backbone conformation with these changes. These results Suggest that differences in the coagulation properties of milks containing either kappa-casein A or kappa-casein B are more likely to be related to factors, such as micelle size or charge, than to structural differences arising from altered backbone conformation of the macropeptide segments of the kappa-caseins.