Improving electrochemical hybridization assays with restriction enzymes.

Nucleic acids in blood are early indicators of disease that could be detected by point-of-care biosensors if sufficiently sensitive and facile sensors existed. Electrochemical hybridization assays are sensitive and specific but are limited to very short nucleic acids. We have developed a restriction enzyme-assisted electrochemical hybridization (REH) assay for improved nucleic acid detection. By incorporating target-specific restriction enzymes, we detect long nucleic acids, with performance dependent on the location of the cut site relative to the electrode surface. Thus, we have further established guidelines for REH design to serve as a generalizable platform for robust electrochemical detection of long nucleic acids.

Carbon Electrode-Based Biosensing Enabled by Biocompatible Surface Modification with DNA and Proteins.

Modification of electrodes with biomolecules is an essential first step for the development of bioelectrochemical systems, which are used in a variety of applications ranging from sensors to fuel cells. Gold is often used because of its ease of modification with thiolated biomolecules, but carbon screen-printed electrodes (SPEs) are gaining popularity due to their low cost and fabrication from abundant resources. However, their effective modification with biomolecules remains a challenge; the majority of work to-date relies on nonspecific adhesion or broad amide bond formation to chemical handles on the electrode surface. By combining facile electrochemical modification to add an aniline handle to electrodes with a specific and biocompatible oxidative coupling reaction, we can readily modify carbon electrodes with a variety of biomolecules. Importantly, both proteins and DNA maintain bioactive conformations following coupling. We have then used biomolecule-modified electrodes to generate microbial monolayers through DNA-directed immobilization. This work provides an easy, general strategy to modify inexpensive carbon electrodes, significantly expanding their potential as bioelectrochemical systems.

The emergence of psychoanalytical electrochemistry: the translation of MDD biomarker discovery to diagnosis with electrochemical sensing.

The disease burden and healthcare costs of psychiatric diseases along with the pursuit to understand their underlying biochemical mechanisms have led to psychiatric biomarker investigations. Current advances in evaluating candidate biomarkers for psychiatric diseases, such as major depressive disorder (MDD), focus on determining a specific biomarker signature or profile. The origins of candidate biomarkers are heterogenous, ranging from genomics, proteomics, and metabolomics, while incorporating associations with clinical characterization. Prior to clinical use, candidate biomarkers must be validated by large multi-site clinical studies, which can be used to determine the ideal MDD biomarker signature. Therefore, identifying valid biomarkers has been challenging, suggesting the need for alternative approaches. Following validation studies, new technology must be employed to transition from biomarker discovery to diagnostic biomolecular profiling. Current technologies used in discovery and validation, such as mass spectroscopy, are currently limited to clinical research due to the cost or complexity of equipment, sample preparation, or measurement analysis. Thus, other technologies such as electrochemical detection must be considered for point-of-care (POC) testing with the needed characteristics for physicians' offices. This review evaluates the advantages of using electrochemical sensing as a primary diagnostic platform due to its rapidity, accuracy, low cost, biomolecular detection diversity, multiplexed capacity, and instrument flexibility. We evaluate the capabilities of electrochemical methods in evaluating current candidate MDD biomarkers, individually and through multiplexed sensing, for promising applications in detecting MDD biosignatures in the POC setting.

The prevention of firearm injuries in Canadian youth.

Firearm injuries are a significant and preventable cause of death in Canadian youth. Adolescent and young adult males are disproportionately affected; however, firearm-related deaths occur in youth of all ages. Canada's rate of firearm ownership is lower than that of the USA, but high compared with other upper-income countries. The availability of firearms to youth is an important factor in adolescent suicide, unintentional firearm deaths, gang homicide and school shootings. Guns should not be kept in homes or environments where children and adolescents live or play. Screening for the presence of a firearm in the home is an essential part of the safety assessment of a depressed or suicidal youth, and removal of the firearm from the home must be recommended in this situation. Legislative measures to strictly control the acquisition, transport, ownership and storage of firearms, and to reduce smuggling of firearms, are also recommended.

The Impact of Age and Cognitive Reserve on Resting-State Brain Connectivity.

Cognitive reserve (CR) is a protective mechanism that supports sustained cognitive function following damage to the physical brain associated with age, injury, or disease. The goal of the research was to identify relationships between age, CR, and brain connectivity. A sample of 90 cognitively normal adults, ages 45-64 years, had their resting-state brain activity recorded with electroencephalography (EEG) and completed a series of memory and executive function assessments. CR was estimated using years of education and verbal IQ scores. Participants were divided into younger and older age groups and low- and high-CR groups. We observed greater left- than right-hemisphere coherence in younger participants, and greater right- than left-hemisphere coherence in older participants. In addition, greater coherence was observed under eyes-closed than eyes-open recording conditions for both low-CR and high-CR participants, with a more substantial difference between recording conditions in individuals high in CR regardless of age. Finally, younger participants low in CR exhibited greater mean coherence than younger participants high in CR, whereas the opposite pattern was observed in older participants, with greater coherence in older participants high in CR. Together, these findings suggest the possibility of a shift in the relationship between CR and brain connectivity during aging.

A Chemical Biology Study of Human Pluripotent Stem Cells Unveils HSPA8 as a Key Regulator of Pluripotency.

Chemical biology methods such as high-throughput screening (HTS) and affinity-based target identification can be used to probe biological systems on a biomacromolecule level, providing valuable insights into the molecular mechanisms of those systems. Here, by establishing a human embryonal carcinoma cell-based HTS platform, we screened 171,077 small molecules for regulators of pluripotency and identified a small molecule, Displurigen, that potently disrupts hESC pluripotency by targeting heat shock 70-kDa protein 8 (HSPA8), the constitutively expressed member of the 70-kDa heat shock protein family, as elucidated using affinity-based target identification techniques and confirmed by loss-of-function and gain-of-function assays. We demonstrated that HSPA8 maintains pluripotency by binding to the master pluripotency regulator OCT4 and facilitating its DNA-binding activity.

Acclimating international graduate students to professional engineering ethics.

This article describes the education portion of an ongoing grant-sponsored education and research project designed to help graduate students in all engineering disciplines learn about the basic ethical principles, rules, and obligations associated with engineering practice in the United States. While the curriculum developed for this project is used for both domestic and international students, the educational materials were designed to be sensitive to the specific needs of international graduate students. In recent years, engineering programs in the United States have sought to develop a larger role for professional ethics education in the curriculum. Accreditation requirements, as well as pressures from the private sector, have helped facilitate this shift in focus. Almost half of all engineering graduate students in the U.S. are international students. Further, research indicates that the majority of these students will remain in the U.S. to work post-graduation. It is therefore in the interest of the profession that these students, coming from diverse backgrounds, receive some formal exposure to the professional and ethical expectations and norms of the engineering profession in the United States to help ensure that they have the knowledge and skills--non-technical as well as technical--required in today's engineering profession. In becoming acculturated to professional norms in a host country, international students face challenges that domestic students do not encounter; such as cultural competency, language proficiency, and acculturation stress. Mitigating these challenges must be a consideration in the development of any effective education materials. The present article discusses the project rationale and describes the development of on-line instructional materials aimed at helping international engineering graduate students acclimate to professional engineering ethics standards in the United States. Finally, a brief data summary of students' perceptions of the usefulness of the content and instructional interface is provided to demonstrate the initial effectiveness of the materials and to present a case for project sustainability.

Correlation of a reported history of chickenpox with seropositive immunity in pregnant women.

OBJECTIVE: To evaluate to what degree a positive verbal history of prior chickenpox infection correlates with current immunity. STUDY DESIGN: Patients presenting for prenatal registration at Naval Medical Center, San Diego, from January through June 2002 were candidates to participate in the study. Each patient was asked about her personal history of chickenpox. A blood sample was then obtained for an enzyme-linked immunosorbent assay IgG antibody test. RESULTS: Results were obtained on 1,085 patients. Of the 940 evaluable patients who reported a positive history of varicella, 904 (96.2%) were serologically immune; 21 (2.2%) of them had a negative antibody titer, and 15 (1.6%) of them had an equivocal titer. The overall seronegativity rate was 4.14% for all patients enrolled. CONCLUSION: There is a strong correlation between a reported history of chickenpox and serum immunity. Universal screening does not seem necessary, but education of susceptible individuals is warranted.