Notecarin D binds human factor V and factor Va with high affinity in the absence of membranes.

Notecarin D (NotD) is a prothrombin (ProT) activator in the venom of the tiger snake, Notechis scutatus, and a factor Xa (FXa) homolog. NotD binds specifically to the FXa binding site expressed on factor V (FV) upon activation to factor Va (FVa) by thrombin. NotD active site-labeled with 5-fluorescein ([5F]FFR-NotD) binds FV and FVa with remarkably high affinity in the absence of phospholipids (K(D) 12 and ≤ 0.01 nm, respectively). In the presence of membranes, the affinity of [5F]FFR-NotD for FVa is similar, but increased ∼55-fold for FV. Binding of FXa active site-labeled with Oregon Green to FV and FVa in the presence of phospholipids is ∼5,000- and ∼80-fold weaker than [5F]FFR-NotD, respectively. NotD reports FVa and not FV binding by a 3-fold increase in tripeptide substrate hydrolysis, demonstrating allosteric regulation by FVa. The NotD·FVa·membrane complex activates ProT with K(m)((app)) similar to prothrombinase, and ∼85-fold weaker without membranes. Active site-blocked NotD exhibits potent anticoagulant activity in plasma thrombin generation assays, representing inhibition of productive prothrombinase assembly and possible disruption of FXa inhibition by the tissue factor pathway inhibitor. The results show that high affinity binding of NotD to FVa is membrane-independent, unlike the strict membrane dependence of FXa for high affinity FVa binding.

The School for Science and Math at Vanderbilt: An Innovative Research-Based Program for High School Students.

The School for Science and Math at Vanderbilt (SSMV) is an innovative partnership program between a Research I private university and a large urban public school system. The SSMV was started in 2007 and currently has 101 students enrolled in the program, with a total of 60 students who have completed the 4-yr sequential program. Students attend the SSMV for one full day per week during the school year and 3-6 wk in the summers following their ninth- to 11th-grade years, with each grade of 26 students coming to the Vanderbilt campus on a separate day. The research-based curriculum focuses on guiding students through the process of learning to develop questions and hypotheses, designing projects and performing analyses, and communicating results of these projects. The SSMV program has elevated the learning outcomes of students as evidenced by increased achievement scores relative to a comparison group of students; has provided a rigorous research-based science, technology, engineering, and mathematics elective curriculum that culminates in a Summer research internship; has produced 27 Intel and Siemens semifinalists and regional finalists over the past 4 yr; and has supported the development of writing and communication skills resulting in regional and national oral presentations and publications in scientific journals.

A comparison of the presumptive luminol test for blood with four non-chemiluminescent forensic techniques.

Presumptive blood detection tests are used by forensic investigators to detect trace amounts of blood or to investigate suspicious stains. Through the years, a number of articles have been published on the popular techniques of the day. However, there is no single paper that critiques and compares the five most common presumptive blood detection tests currently in use: luminol, phenolphthalein (Kastle-Meyer), leucomalachite green, Hemastix and the forensic light source. The present authors aimed to compare the above techniques with regard to their sensitivity, ease of use and safety. The luminol test was determined to be the most sensitive of the techniques, while Hemastix is a suitable alternative when the luminol test is not appropriate.

Attempted cleaning of bloodstains and its effect on the forensic luminol test.

The forensic luminol test has long been valued for its ability to detect trace amounts of blood that are invisible to the naked eye. This is the first quantitative study to determine the effect on the luminol test when an attempt is made to clean bloodstained tiles with a known interfering catalyst (bleach). Tiles covered with either wet or dry blood were tested, and either water or sodium hypochlorite solution (bleach) was used to clean the tiles. As expected, the chemiluminescence intensity produced when luminol was applied generally decreased with the number of times that a tile was cleaned with water, until the chemiluminescence was neither visible nor detectable. However, when the tiles were cleaned with bleach there was an initial drop in chemiluminescence intensity, followed by a rise to a consistently high value, visibly indistinguishable from that of blood. Examination of bleach drying time suggested that any interfering effect becomes negligible after 8 h.