Journal of nature and science最新文献

Previous studies have revealed that p53 heterozygous (p53+/-) mice are extremely susceptible to radiation-induced tumorigenesis. To investigate whether genetic background influences radiation induced tumor susceptibility, we crossed p53+/- 129/Sv mice with genetically diverse strains to generate p53+/- F1 hybrids. The results showed that genetic background had a profound impact on tumor latency after exposure to gamma radiation, while the tumor spectrum did not change. We further characterized the thymic lymphomas that arose in the p53+/- mice by genome-wide loss of heterozygosity (LOH) analyses and found that genetic background strongly influenced the frequency of LOH and the loss of which parental allele on different chromosomes. Further research is needed to identify which genetic variations control the LOH patterns in radiation-induced thymic lymphomas and to evaluate its relevance to human cancers.

Influenza infection is the cause of thousands of hospitalizations and deaths each year; infection during pregnancy results in increased morbidity and mortality. Underserved women are particularly susceptible to not receiving recommended vaccinations. This project explored the effect of a simple paper based prompt on the influenza vaccination rate in a resident continuity clinic for the underserved. Using this reminder to providers to discuss the influenza vaccination with their patients, we were able to increase vaccination rates in our clinic from 2.2% to 14.2%. This implementation of a simple, low cost, low tech prompt to providers increased the rate of influenza vaccination in our clinic and we present this approach as an easy to implement method of improving vaccination rates. We also suggest this method as an alternative to an alert in the electronic medical record in situations where the electronic medical record may not be accessed during every patient encounter.

Aggressive behavior in Drosophila melanogaster serves to acquire or defense vital resources such as food, territory or access to mates. Flies learn from previous fighting experience and modify and adapt their behavior to new situations, suggesting that learning and memory play a major role in agonistic encounters. Prior fighting experience influences the outcome of later contests: losing a fight increases the probability of losing second contests, revealing the formation of a "loser" effect. In a recent publication, we developed a new behavioral arena that eliminates handling of flies prior to, during and after fights to study the learning and memory associated with aggression. We compared two handling procedures commonly used in laboratories to study aggression with the new chambers and demonstrated that handling negatively influences aggression and prevents "loser" effect formation. In addition, we observed new aspects of behavior such as the formation of robust winner effects.

Leukemia inhibitory factor (LIF), a cytokine that belongs to the interleukin-6 family, regulates multiple important biological functions. Recently, we found that LIF is an important negative regulator of p53 in human colorectal cancer cells. LIF negatively regulates p53 protein levels and functions by activation of the Stat3 signaling pathway, which in turn induces the expression of ID1, the helix-loop-helix (HLH) protein inhibitor of differentiation and DNA binding. ID1 increases MDM2 expression at both mRNA and protein levels to accelerate p53 protein degradation. Overexpression of LIF increases chemoresistance of cultured colorectal cancer cells and colorectal xenograft tumors in a largely p53-dependent manner. Furthermore, LIF is overexpressed in a large percentage of human colorectal cancer specimens and LIF overexpression is associated with a poor prognosis in colorectal cancer patients. Our study revealed a new role of LIF in tumorigenesis through regulation of the p53 signaling pathway.

Disruption of WNT/β-catenin signaling causes muscle developmental defects. However, it has been unclear how WNT/β-catenin signaling regulates each step of myogenesis. The in vitro culture of primary myoblasts and C2C12 cells (a myoblast cell line) has the ability to differentiate into myofibers in culture with differentiation inducers. These in vitro systems are useful to investigate each step of muscle development, ranging from cell proliferation to homeostasis, under the control of experimental conditions. Our recent study shows that WNT/β-catenin signaling can regulate myogenesis in a temporal specific manner by controlling the gene expression of cyclin A2 (Ccna2) and cell division cycle 25C (Cdc25c) during myoblast proliferation and fermitin family homolog 2 (Fermt2) during myoblast fusion and differentiation, respectively. In the well-differentiated myofibers, WNT/β-catenin signaling plays a role in the maintenance of their structure through a cadherin/β-catenin/actin complex formation, which is important for connecting a myofiber's cytoskeleton to the surrounding extracellular matrix. Thus, our recent study coupled with previous findings indicates that WNT/β-catenin signaling regulates myogenesis in a variety of ways, and any failure of these steps of myogenesis causes muscle developmental defects.

Recent advances in theory of solid state nuclear magnetic resonance (NMR) such as Floquet-Magnus expansion and Fer expansion, address alternative methods for solving a time-dependent linear differential equation which is a central problem in quantum physics in general and solid-state NMR in particular. The power and the salient features of these theoretical approaches that are helpful to describe the time evolution of the spin system at all times are presented. This review article presents a broad view of manipulations of spin systems in solid-state NMR, based on milestones theories including the average Hamiltonian theory and the Floquet theory, and the approaches currently developing such as the Floquet-Magnus expansion and the Fer expansion. All these approaches provide procedures to control and describe the spin dynamics in solid-state NMR. Applications of these theoretical methods to stroboscopic and synchronized manipulations, non-synchronized experiments, multiple incommensurated frequencies, magic-angle spinning samples, are illustrated. We also reviewed the propagators of these theories and discussed their convergences. Note that the FME is an extension of the popular Magnus Expansion and Average Hamiltonian Theory. It aims is to bridge the AHT to the Floquet Theorem but in a more concise and efficient formalism. Calculations can then be performed in a finite-dimensional Hilbert space instead of an infinite dimensional space within the so-called Floquet theory. We expected that the FME will provide means for more accurate and efficient spin dynamics simulation and for devising new RF pulse sequence.