CT as a first-line modality in elderly patients with stable blunt chest trauma.

Purpose: Blunt thoracic injuries are common among elderly patients and may be a common cause of morbidity and death from blunt trauma injuries. We aimed to examine the impact of chest CT on the diagnosis and change of management plan in elderly patients with stable blunt chest trauma. We hypothesized that chest CT may play an important role in providing optimal management to this subgroup of trauma patients.

The emergency department length of stay: Is the time running out?

Purpose: To examine the relationships between emergency department length of stay (EDLOS) with hospital length of stay (HLOS) and clinical outcome in hemodynamically stable trauma patients.

Methods: Prospective data collected for 2 years from consecutive trauma patients admitted to the trauma resuscitation bay. Only stable blunt trauma patients with appropriate trauma triage criteria requiring trauma team activation were included in the study.

Effect of the reflectional symmetry on the coherent hole transport across DNA hairpins.

The coherent hole transfer in three types of DNA hairpins containing strands with adenine (A) and guanine (G) nucleobases has been studied. The investigated hairpins involve AGGAn, AGAGA, or (AG)A strands that connect the hole donor and hole acceptor located on opposite ends of hairpins. The positive charge transfer from the photo-excited donor to the acceptor is shown to be slower for AGGAn in comparison with AGAGA and (AG)A sequences.

Deep-hole transfer leads to ultrafast charge migration in DNA hairpins.

Charge transport through the DNA double helix is of fundamental interest in chemistry and biochemistry, but also has potential technological applications such as for DNA-based nanoelectronics. For the latter, it is of considerable interest to explore ways to influence or enhance charge transfer. In this Article we demonstrate a new mechanism for DNA charge transport, namely 'deep-hole transfer', which involves long-range migration of a hole through low-lying electronic states of the nucleobases.

Conformationally Gated Charge Transfer in DNA Three-Way Junctions.

Molecular structures that direct charge transport in two or three dimensions possess some of the essential functionality of electrical switches and gates. We use theory, modeling, and simulation to explore the conformational dynamics of DNA three-way junctions (TWJs) that may control the flow of charge through these structures. Molecular dynamics simulations and quantum calculations indicate that DNA TWJs undergo dynamic interconversion among "well stacked" conformations on the time scale of nanoseconds, a feature that makes the junctions very different from linear DNA duplexes.

Charge Transport across DNA-Based Three-Way Junctions.

DNA-based molecular electronics will require charges to be transported from one site within a 2D or 3D architecture to another. While this has been shown previously in linear, π-stacked DNA sequences, the dynamics and efficiency of charge transport across DNA three-way junction (3WJ) have yet to be determined. Here, we present an investigation of hole transport and trapping across a DNA-based three-way junction systems by a combination of femtosecond transient absorption spectroscopy and molecular dynamics simulations.

Impact of a single base pair substitution on the charge transfer rate along short DNA hairpins.

Numerical studies of hole migration along short DNA hairpins were performed with a particular emphasis on the variations of the rate and quantum yield of the charge separation process with the location of a single guanine:cytosine (G:C) base pair. Our calculations show that the hole arrival rate increases as the position of the guanine:cytosine base pair shifts from the beginning to the end of the sequence. Although these results are in agreement with recent experimental findings, the mechanism governing the charge migration along these sequences is revisited here.

Between superexchange and hopping: an intermediate charge-transfer mechanism in poly(A)-poly(T) DNA hairpins.

We developed a model for hole migration along relatively short DNA hairpins with fewer that seven adenine (A):thymine (T) base pairs. The model was used to simulate hole migration along poly(A)-poly(T) sequences with a particular emphasis on the impact of partial hole localization on the different rate processes. The simulations, performed within the framework of the stochastic surrogate Hamiltonian approach, give values for the arrival rate in good agreement with experimental data.

DNA base pair stacks with high electric conductance: a systematic structural search.

We report a computational search for DNA π-stack structures exhibiting high electric conductance in the hopping regime, based on the INDO/S calculations of electronic coupling and the method of data analysis called k-means clustering. Using homogeneous poly(G)-poly(C) and poly(A)-poly(T) stacks as the simplest structural models, we identify the configurations of neighboring G:C and A:T pairs that allow strong electronic coupling and, therefore, molecular electric conductance much larger than the values reported for the corresponding reference systems in the literature. A computational approach for modeling the impact of thermal fluctuations on the averaged dimer structure was also proposed and applied to the [(G:C),(G:C)] and [(A:T),(A:T)] duplexes.

Electronic excitation energy transfer between nucleobases of natural DNA.

Transfer of the electronic excitation energy in calf thymus DNA is studied by time-resolved fluorescence spectroscopy. The fluorescence anisotropy, after an initial decay starting on the femtosecond time scale, dwindles down to ca. 0.

Exponential distance dependence of photoinitiated stepwise electron transfer in donor-bridge-acceptor molecules: implications for wirelike behavior.

Donor-bridge-acceptor (D-B-A) systems in which a 3,5-dimethyl-4-(9-anthracenyl)julolidine (DMJ-An) chromophore and a naphthalene-1,8:4,5-bis(dicarboximide) (NI) acceptor are linked by oligomeric 2,7-fluorenone (FN(n)) bridges (n = 1-3) have been synthesized. Selective photoexcitation of DMJ-An quantitatively produces DMJ(+•)-An(-•), and An(-•) acts as a high-potential electron donor. Femtosecond transient absorption spectroscopy in the visible and mid-IR regions showed that electron transfer occurs quantitatively in the sequence: DMJ(+•)-An(-•)-FN(n)-NI → DMJ(+•)-An-FN(n)(-•)-NI → DMJ(+•)-An-FN(n)-NI(-•).

Effects of various halogen anions and cations of alkali metals on energetics of excess charge recombination in stilbene donor-acceptor capped DNA hairpins.

DNA hairpin conjugates with a stilbenedicarboxamide (Sa) hole donor and a stilbenediether (Sd) hole acceptor are considered as model systems for studying charge recombination (CR) of excess charges in DNA. Using the method of thermodynamic integration, we estimated the relative free energies of this process in hairpins with three adenine:thymine pairs between Sa and Sd surrounded by 1 M aqueous solutions of ionic compounds M(+)Cl(-) (M = Li, Na, K) and Na(+)X(-) (X = F, Cl, Br, I). The values of this quantity were calculated with respect to the free energy for the same hairpin in the 1 M NaCl aqueous solution.

Effect of electrostatic interactions and dynamic disorder on the distance dependence of charge transfer in donor-bridge-acceptor systems.

Using a tight-binding model of charge transport in systems with static and dynamic disorder, we present a theoretical study of the positive charge transfer in molecular assemblies that involve a hole donor and an acceptor connected by fluorene and phenyl bridges. Two parameters that determine the rate of charge transfer within the proposed model are the charge transfer integral between neighboring units and the site energies. Fluctuations in the values of the charge transfer integral and the energy landscape for hole transport were calculated by taking into account variations of the dihedral angle between neighboring units and electrostatic interaction of positive charge moving along the bridge and the negative charge that remains on the hole donor.

Effect of GC base pairs on charge transfer through DNA hairpins: the importance of electrostatic interactions.

DNA hairpins in which an electron donor and an electron acceptor are attached to the ends are excellent model systems for the study of charge transfer in weakly coupled pi-stacked systems. In this communication we report on a computational study of the effect of the base pair sequence in these DNA hairpins on the kinetics of charge transfer. We show that the rate of charge transfer strongly depends on the actual position of a GC base pair in a sequence that otherwise only contains AT base pairs.

Does progesterone inhibit bacteria-stimulated interleukin-8 production by lower genital tract epithelial cells?

Objective: Progesterone (P(4)) has been clinically shown to prevent the recurrence of preterm birth. The mechanism(s) of action is unclear, but may involve modulation of the immunologic inflammatory response of the lower genital tract. We evaluated the effects of P(4) on interleukin-8 (IL-8) production by vaginal and cervical epithelial cells stimulated with bacterial species that are commonly associated with preterm birth.

A prospective, randomized, controlled, multicenter study of a real-time, intraoperative probe for positive margin detection in breast-conserving surgery.

Background: This randomized, double-arm trial was designed to study the benefit of a novel device (MarginProbe, Dune Medical Devices, Caesarea, Israel) in intraoperative margin assessment for breast-conserving surgery (BCS) and the associated reduction in reoperations.

Methods: In the device group, the probe was applied to the lumpectomy specimen and additional tissue was excised according to device readings. Study arms were compared by reoperation rates and by correct surgical reaction confirmed by histology.

Effect of structural dynamics on charge transfer in DNA hairpins.

We present a theoretical study of the positive charge transfer in stilbene-linked DNA hairpins containing only AT base pairs using a tight-binding model that includes a description of structural fluctuations. The parameters are the charge transfer integral between neighboring units and the site energies. Fluctuations in these parameters were studied by a combination of molecular dynamics simulations of the structural dynamics and density functional theory calculations of charge transfer integrals and orbital energies.

Absolute rates of hole transfer in DNA.

Absolute rates of hole transfer between guanine nucleobases separated by one or two A:T base pairs in stilbenedicarboxamide-linked DNA hairpins were obtained by improved kinetic analysis of experimental data. The charge-transfer rates in four different DNA sequences were calculated using a density-functional-based tight-binding model and a semiclassical superexchange model. Site energies and charge-transfer integrals were calculated directly as the diagonal and off-diagonal matrix elements of the Kohn-Sham Hamiltonian, respectively, for all possible combinations of nucleobases.

Embryonic radial glia bridge spinal cord lesions and promote functional recovery following spinal cord injury.

Radial glial cells are neural stem cells (NSC) that are transiently found in the developing CNS. To study radial glia, we isolated clones following immortalization of E13.5 GFP rat neurospheres with v-myc.

Artificial genetic selection for an efficient translation initiation site for expression of human RACK1 gene in Escherichia coli.

In bacterial expression systems, translation initiation is usually the rate limiting and the least predictable stage of protein synthesis. Efficiency of a translation initiation site can vary dramatically depending on the sequence context. This is why many standard expression vectors provide very poor expression levels of some genes.

Microtubules are critical for radial glial morphology: possible regulation by MAPs and MARKs.

Radial glia are a polarized cell type that in most neural regions appear only transiently during development. They have long been recognized as glia or glial progenitors that support neuronal migration. Recent evidence indicates that radial glia also give rise to neurons and appear to be a major population of dividing precursor cells in the embryonic cortical ventricular zone.

DNA splicing by directed ligation (SDL).

Splicing by directed ligation (SDL) is a method of in-phase joining of PCR-generated DNA fragments that is based on a pre-designed combination of class IIS restriction endonuclease recognition and cleavage sites. Since these enzymes cleave outside of their recognition sites, the resulting sticky end can have any desired sequence, and the site itself can be removed and does not appear in the final spliced DNA product. SDL is based on the addition of class IIS recognition sites onto primers used to amplify DNA sequences.

Charge hopping in DNA.

The efficiency of charge migration through stacked Watson-Crick base pairs is analyzed for coherent hole motion interrupted by localization on guanine (G) bases. Our analysis rests on recent experiments, which demonstrate the competition of hole hopping transitions between nearest neighbor G bases and a chemical reaction of the cation G(+) with water. In addition, it has been assumed that the presence of units with several adjacent stacked G bases on the same strand leads to the additional vibronic relaxation process (G(+)G.