The frequency natural antisense transcript first promotes, then represses, frequency gene expression via facultative heterochromatin.

The circadian clock is controlled by a network of interconnected feedback loops that require histone modifications and chromatin remodeling. Long noncoding natural antisense transcripts (NATs) originate from Period in mammals and frequency (frq) in Neurospora. To understand the role of NATs in the clock, we put the frq antisense transcript qrf (frq spelled backwards) under the control of an inducible promoter.

The histone H3 lysine 9 methyltransferase DIM-5 modifies chromatin at frequency and represses light-activated gene expression.

The transcriptional program controlling the circadian rhythm requires coordinated regulation of chromatin. Characterization of the chromodomain helicase DNA-binding enzyme CHD1 revealed DNA methylation in the promoter of the central clock gene frequency (frq) in Neurospora crassa. In this report, we show that the DNA methylation at frq is not only dependent on the DNA methyltransferase DIM-2 but also on the H3K9 methyltransferase DIM-5 and HP1.

Regulated DNA methylation and the circadian clock: implications in cancer.

Since the cloning and discovery of DNA methyltransferases (DNMT), there has been a growing interest in DNA methylation, its role as an epigenetic modification, how it is established and removed, along with the implications in development and disease. In recent years, it has become evident that dynamic DNA methylation accompanies the circadian clock and is found at clock genes in Neurospora, mice and cancer cells. The relationship among the circadian clock, cancer and DNA methylation at clock genes suggests a correlative indication that improper DNA methylation may influence clock gene expression, contributing to the etiology of cancer.

A universal cloning method based on yeast homologous recombination that is simple, efficient, and versatile.

Cloning by homologous recombination (HR) in Saccharomyces cerevisiae is an extremely efficient and cost-effective alternative to other methods of recombinant DNA technologies. Unfortunately, it is incompatible with all the various specialized plasmids currently used in microbiology and biomedical research laboratories, and is therefore, not widely adopted. In an effort to dramatically improve the versatility of yeast gap-repair cloning and make it compatible with any DNA plasmid, we demonstrate that by simply including a yeast-cloning cassette (YCC) that contains the 2-micron origin of replication (2μm ori) and the ura3 gene for selection, multiple DNA fragments can be assembled into any DNA vector.

Synthetic and crystallographic studies of a new inhibitor series targeting Bacillus anthracis dihydrofolate reductase.

Bacillus anthracis, the causative agent of anthrax, poses a significant biodefense danger. Serious limitations in approved therapeutics and the generation of resistance have produced a compelling need for new therapeutic agents against this organism. Bacillus anthracis is known to be insensitive to the clinically used antifolate, trimethoprim, because of a lack of potency against the dihydrofolate reductase enzyme.

Electrophysiologic characteristics of anger-triggered arrhythmias.

Background: Anger can precipitate ventricular arrhythmias in patients with implantable cardioverter-defibrillators (ICDs). Determining electrophysiologic characteristics of anger-triggered arrhythmias may help elucidate the mechanisms that link emotion and arrhythmia.

Objectives: We sought to compare the morphology and initiation pattern between ventricular arrhythmias that are triggered by anger and those that are not.

Highly efficient ligands for dihydrofolate reductase from Cryptosporidium hominis and Toxoplasma gondii inspired by structural analysis.

The search for effective therapeutics for cryptosporidiosis and toxoplasmosis has led to the discovery of novel inhibitors of dihydrofolate reductase (DHFR) that possess high ligand efficiency: compounds with high potency and low molecular weight. Detailed analysis of the crystal structure of dihydrofolate reductase-thymidylate synthase from Cryptosporidium hominis and a homology model of DHFR from Toxoplasma gondii inspired the synthesis of a new series of compounds with a propargyl-based linker between a substituted 2,4-diaminopyrimidine and a trimethoxyphenyl ring. An enantiomerically pure compound in this series exhibits IC50 values of 38 and 1 nM against C.

Structure-activity relationships of Bacillus cereus and Bacillus anthracis dihydrofolate reductase: toward the identification of new potent drug leads.

New and improved therapeutics are needed for Bacillus anthracis, the etiological agent of anthrax. To date, antimicrobial agents have not been developed against the well-validated target dihydrofolate reductase (DHFR). In order to address whether DHFR inhibitors could have potential use as clinical agents against Bacillus, 27 compounds were screened against this enzyme from Bacillus cereus, which is identical to the enzyme from B.

Salicylic acid activates sigma factor B by rsbU-dependent and -independent mechanisms.

Salicylic acid (SAL) may impact Staphylococcus aureus virulence by activating the sigB operon (rsbU-V-W-sigB), thus leading to reductions in alpha-toxin production and decreased fibronectin binding (L. I. Kupferwasser et al.

Psychological traits and emotion-triggering of ICD shock-terminated arrhythmias.

Objective: We have previously reported on the triggering of arrhythmia and hence, implanted cardioverter-defibrillators (ICD) shock by strong emotion. The purpose of the present study was to examine whether concordant psychological traits distinguish patients who experience emotion-triggered ICD shock.

Methods: Two hundred forty ICD patients completed the Speilberger Trait Anxiety and Anger Inventories and Anger Expression Scale, and the abridged Cook-Medley Hostility Scale approximately 2 months after ICD implantation.

Doxorubicin cardiotoxicity: prevention of congestive heart failure with serial cardiac function monitoring with equilibrium radionuclide angiocardiography in the current era.

Background: Congestive heart failure (CHF) is among the most serious toxicities of doxorubicin, a potent cancer chemotherapeutic agent. Serial left ventricular ejection fraction (LVEF) monitoring during doxorubicin therapy for preventing CHF was proposed over 20 years ago. The current utility and cost-effectiveness of this approach in the present era are not known.

Emotional and physical precipitants of ventricular arrhythmia.

Background: Observational studies have suggested that psychological stress increases the incidence of sudden cardiac death. Whether emotional or physical stressors can trigger spontaneous ventricular arrhythmias in patients at risk has not been systematically evaluated.

Methods And Results: Patients with implantable cardioverter-defibrillators (ICDs) were given diaries to record levels of defined mood states and physical activity, using a 5-point intensity scale, during 2 periods preceding spontaneously occurring ICD shocks (0 to 15 minutes and 15 minutes to 2 hours) and during control periods 1 week later.

Pharmacologic stress perfusion imaging with adenosine: role of simultaneous low-level treadmill exercise.

Background: Adenosine is commonly used for pharmacologic stress myocardial perfusion imaging (MPI). However, it frequently results in adverse effects, and the subdiaphragmatic tracer uptake may interfere with the image interpretation. Our aim was to determine the feasibility of combining low-level treadmill exercise with adenosine MPI and its impact on adverse effects, image quality, and myocardial ischemia.