NOVEL G-QUADRUPLEX BINDERS WITH POTENTIAL FOR A DUAL DNA CROSS-LINKING MECHANISM OF ACTION

Genomic DNA is organized around the double-stranded of B-form DNA, which is both durable and flexible enough to store and pass on genetic information. Once freed from the associations of an extended complimentary sequence, single stranded DNA and RNA can adopt a vast array of stable secondary structure motifs, such as stem-loop, pseudo-knots, and tetra-loops, ideal for its involvement in biological settings other than as a store of genetic information. Originally, alkylating agents were used as mustard gas and related chemical weapons in World War I. Alkylating agents, in general, can react with one or two different 7-N-guanine residues and could potentially result in the cross-linkage of DNA strands, preventing uncoiling of the DNA double helix leading to cell death. More recent evidence show that guanine-rich nucleic acids can fold into distinctive four-stranded conformers found in telomeric DNA repeats (i.e. TTAGGG), also known as G-quadruplexes (G4), as well as in sequences in the promoter and other regulatory regions of genes, especially those involved in cellular proliferation. Small molecules that induce the formation of, and selectively bind to, G4 structures are of interest for development as potential anticancer therapeutics. Novel 10-oxoanthracene and substituted anthracenyl isoxazole esters (AIEs) were synthesized and characterized based on NMR studies. To date, quarfloxin is the only G-quadruplex ligand from the large number developed to progress to clinical evaluation. The synthesis, structural characterization, and biological studies will be presented

Molecular Modeling Assisted Design and Synthesis of Unsymmetrical Anthracene Isoxazole Small Molecule Anti-tumor Agents

There are several isoxazoles in general medical practice and their metabolic fate and disposition is well known, and thus, this heterocyclic ring is often considered among the privileged scaffolds or templates for drug design and discovery. Many examples can be found of 3-aryl-isoxazoles which in theory have a chiral axis, yet actual experimental examples of direct determinations of isoxazole rotational barriers are few and far between. The dihedral angle of the 3-aryl to isoxazole bond in antibacterials of the oxacillin series increased with substitution in the 2- and 6- positions of the phenyl. Although his calculated barrier was low, this implied that atropisomers are possible for unsymmetrical substitution. The chirality of these systems differs from that of other compounds as their configuration is inverted by rotation about single bonds and can be accomplished by thermal equilibration. Thus, depending on the barrier to rotation, some of these atropisomers may only be isolated at low temperatures, if at all

Pronghorn Habitat Suitability in the Texas Panhandle

Habitat quality is an important factor that can greatly affect wildlife populations. Pronghorn (Antilocapra americana) habitat in the Texas Panhandle, USA has been lost through growth of human settlements and agricultural lands. We determined the most pertinent environmental variables affecting habitat selection using multiple methods, including a search of peer-reviewed literature, expert opinion ranking, and habitat suitability modeling. We determined quality and extent of pronghorn habitat in the Texas Panhandle using the MAXENT modeling environment to build a presence-only habitat suitability model based on global positioning system (GPS) locations collected via aerial surveys. Our habitat suitability model indicated that woodlands, agricultural land, and summer precipitation had the greatest contributions to the overall model. Areas with greatest habitat suitability are associated with high pronghorn population densities, particularly in the northwestern corner of the Panhandle. This probabilistic model may serve as a useful tool for pronghorn conservation primarily because it provides insight into what factors are most predictive of their presence, which areas are most suitable for pronghorn, and as a simple, replicable process to identify and evaluate pronghorn habitat

Anthracenyl isoxazole amides (AIMs) stabilize quadruplex DNA structures in telomeric and c-MYC promotor sequences

Approximately 23,000 people are affected by malignant brain and CNS tumors in the United States each year and those afflicted have a median survival rate of only 12–15 months due to the limited treatment options available. The anthracenyl isoxazole amides (AIMs) are a novel class of compounds that have been shown to possess significant anti tumor activity in the NCI 60 cell line panel and to inhibit growth of SNB-19 glioblastoma cells at low micromolar and nanomolar concentrations. The goal of our current research is to characterize the mechanism underlying the anti tumor activity of the AIMs. We hypothesize the mechanism of growth inhibition to involve binding and stabilization of a DNA tertiary structure known as a guanine quadruplex. Various regulatory regions of DNA, such the c-MYC oncogene promoter sequence and repeating sequences formed at the end of telomeres, adopt the quadruplex conformation. Stabilization of quadruplex structures by small-molecule binding ligands has been reported to modulate the expression of genes and inhibit telomerase activity. Down-regulation of certain oncogenes or the inhibition of telomerase can cause tumor cells to undergo apoptosis or become unable to efficiently replicate. To establish whether interactions between the AIMs and quadruplex-forming sequences act to stabilize the quadruplex tertiary structure, circular dichroism spectroscopy (CD) was employed. CD is a method that utilizes the differential absorbance of left and right circularly polarized light to examine the chiral structure of molecules. CD thermal melting studies were conducted to determine whether the AIMs would increase the melting temperature of quadruplex forming sequences as an indication of increased stability. Our results demonstrated the AIMs, at two equivalents, increase the melting temperature (Tm) of both the c-MYC promoter and telomeric sequences by approximately 2–3 °C with strong statistical significance and reproducibility. Utilizing CD allows the use of low micromolar concentrations of DNA and this method will be used in the future to rapidly develop additional structure-activity relationships between novel AIMs and quadruplex forming sequences. Our laboratory has also shown chemical shifts in the imino region upon treatment with the AIMs for both the c-MYC promotor and telomeric sequence by NMR, providing additional evidence of the AIMs interaction with quadruplex structures. Interestingly, fluorescence microscopy of SNB-19 cells treated with AIMs show their localization is primarily in the mitochondria, and mitochondrial DNA contains several other important quadruplex forming sequences. Mitochondrial-dependent apoptosis has been suggested for other quadruplex binding ligands and therefore our future work will examine the potential stabilization of mitochondrial quadruplexes by these and other novel AIMs

Virtual Reality "exergames": A promising countermeasure to improve motivation and restorative effects during long duration spaceflight missions

Long duration spaceflight missions will require novel exercise systems to protect astronaut crew from the detrimental effects of microgravity exposure. The SPRINT protocol is a novel and promising exercise prescription that combines aerobic and resistive training using a flywheel device, and it was successfully employed in a 70-day bed-rest study as well as onboard the International Space Station. Our team created a VR simulation to further augment the SPRINT protocol when using a flywheel ergometer training device (the Multi-Mode Exercise Device or M-MED). The simulation aspired to maximal realism in a virtual river setting while providing real-time biometric feedback on heart rate performance to subjects. In this pilot study, five healthy, male, physically-active subjects aged 35 +/- 9.0 years old underwent 2 weeks of SPRINT protocol, either with or without the VR simulation. After a 1-month washout period, subjects returned for a subsequent 2 weeks in the opposite VR condition. We measured physiological and cognitive variables of stress, performance, and well-being. While physiological effects did not suggest much difference with the VR condition over 2 weeks, metrics of motivation, affect, and mood restoration showed detectable differences, or trended toward more positive outcomes than exercise without VR. These results provide evidence that a well-designed VR "exergaming" simulation with biometric feedback could be a beneficial addition to exercise prescriptions, especially if users are exposed to isolation and confinement.This project was funded through an internal seed grant mechanism by the College of Engineering and the Human Clinical Research Facility at Texas A&M University, College Station, TX, United States

Cleavage by signal peptide peptidase is required for the degradation of selected tail-anchored proteins.

The regulated turnover of endoplasmic reticulum (ER)-resident membrane proteins requires their extraction from the membrane lipid bilayer and subsequent proteasome-mediated degradation. Cleavage within the transmembrane domain provides an attractive mechanism to facilitate protein dislocation but has never been shown for endogenous substrates. To determine whether intramembrane proteolysis, specifically cleavage by the intramembrane-cleaving aspartyl protease signal peptide peptidase (SPP), is involved in this pathway, we generated an SPP-specific somatic cell knockout. In a stable isotope labeling by amino acids in cell culture-based proteomics screen, we identified HO-1 (heme oxygenase-1), the rate-limiting enzyme in the degradation of heme to biliverdin, as a novel SPP substrate. Intramembrane cleavage by catalytically active SPP provided the primary proteolytic step required for the extraction and subsequent proteasome-dependent degradation of HO-1, an ER-resident tail-anchored protein. SPP-mediated proteolysis was not limited to HO-1 but was required for the dislocation and degradation of additional tail-anchored ER-resident proteins. Our study identifies tail-anchored proteins as novel SPP substrates and a specific requirement for SPP-mediated intramembrane cleavage in protein turnover

The HLA Class II Allele Allele DRB1*15 is over-represented in patients with Idiopathic Pulmonary Fibrosis

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive and medically refractory lung disease with a grim prognosis. Although the etiology of IPF remains perplexing, abnormal adaptive immune responses are evident in many afflicted patients. We hypothesized that perturbations of human leukocyte antigen (HLA) allele frequencies, which are often seen among patients with immunologic diseases, may also be present in IPF patients. METHODS/PRINCIPAL FINDINGS: HLA alleles were determined in subpopulations of IPF and normal subjects using molecular typing methods. HLA-DRB1*15 was over-represented in a discovery cohort of 79 Caucasian IPF subjects who had lung transplantations at the University of Pittsburgh (36.7%) compared to normal reference populations. These findings were prospectively replicated in a validation cohort of 196 additional IPF subjects from four other U.S. medical centers that included both ambulatory patients and lung transplantation recipients. High-resolution typing was used to further define specific HLA-DRB1*15 alleles. DRB1*1501 prevalence in IPF subjects was similar among the 143 ambulatory patients and 132 transplant recipients (31.5% and 34.8%, respectively, p = 0.55). The aggregate prevalence of DRB1*1501 in IPF patients was significantly greater than among 285 healthy controls (33.1% vs. 20.0%, respectively, OR 2.0; 95%CI 1.3-2.9, p = 0.0004). IPF patients with DRB1*1501 (n = 91) tended to have decreased diffusing capacities for carbon monoxide (DL(CO)) compared to the 184 disease subjects who lacked this allele (37.8±1.7% vs. 42.8±1.4%, p = 0.036). CONCLUSIONS/SIGNIFICANCE: DRB1*1501 is more prevalent among IPF patients than normal subjects, and may be associated with greater impairment of gas exchange. These data are novel evidence that immunogenetic processes can play a role in the susceptibility to and/or manifestations of IPF. Findings here of a disease association at the HLA-DR locus have broad pathogenic implications, illustrate a specific chromosomal area for incremental, targeted genomic study, and may identify a distinct clinical phenotype among patients with this enigmatic, morbid lung disease

Iron Deficiency and the Well-being of Older Adults: Early Results From a Randomized Nutrition Intervention

Iron deficiency is widespread throughout the developing world. We provide new evidence on the effect of iron deficiency on economic and social prosperity of older adults drawing on data from a random assignment treatment-control design intervention. The Work and Iron Status Evaluation is an on-going study following over 17,000 individuals in Central Java, Indonesia. Half the respondents receive a treatment of 120 mg of iron every week for a year; the controls receive a placebo. Compliance is monitored carefully. Results from the first six months of the intervention are presented for adults age 30 through 70 years. Males who were iron deficient prior to the intervention and who are assigned to the treatment are better off in terms of physical health, psycho-social health and economic success. These men are more likely to be working, sleep less, lose less work time to illness, are more energetic, more able to conduct physically arduous activities and their psycho-social health is better. There is evidence that economic productivity of these males also increased. Among iron-deficient males assigned to the treatment who were also self-employed prior to the baseline, hourly earnings rose substantially and so they earned more on a monthly basis. Benefits for women are in the same direction but the effects are more muted. The results provide unambiguous evidence in support of the hypothesis that health has a causal effect on economic prosperity of males during middle and older ages

<i>CrystalGrower</i>: a generic computer program for Monte Carlo modelling of crystal growth.

From Europe PMC via Jisc Publications RouterHistory: ppub 2020-11-01, epub 2020-11-18Publication status: PublishedA Monte Carlo crystal growth simulation tool, CrystalGrower, is described which is able to simultaneously model both the crystal habit and nanoscopic surface topography of any crystal structure under conditions of variable supersaturation or at equilibrium. This tool has been developed in order to permit the rapid simulation of crystal surface maps generated by scanning probe microscopies in combination with overall crystal habit. As the simulation is based upon a coarse graining at the nanoscopic level features such as crystal rounding at low supersaturation or undersaturation conditions are also faithfully reproduced. CrystalGrower permits the incorporation of screw dislocations with arbitrary Burgers vectors and also the investigation of internal point defects in crystals. The effect of growth modifiers can be addressed by selective poisoning of specific growth sites. The tool is designed for those interested in understanding and controlling the outcome of crystal growth through a deeper comprehension of the key controlling experimental parameters