Circadian Rhythm Dysregulation and Leukemia Development: The Role of Clock Genes as Promising Biomarkers

The circadian clock (CC) is a daily system that regulates the oscillations of physiological processes and can respond to the external environment in order to maintain internal homeostasis. For the functioning of the CC, the clock genes (CG) act in different metabolic pathways through the clock-controlled genes (CCG), providing cellular regulation. The CC’s interruption can result in the development of different diseases, such as neurodegenerative and metabolic disorders, as well as cancer. Leukemias correspond to a group of malignancies of the blood and bone marrow that occur when alterations in normal cellular regulatory processes cause the uncontrolled proliferation of hematopoietic stem cells. This review aimed to associate a deregulated CC with the manifestation of leukemia, looking for possible pathways involving CG and their possible role as leukemic biomarkers.     

Oscillating cascade unsteady aerodynamics including separated flow effects

A mathematical model is developed to predict the effect of flow separation on the unsteady aerodynamic lift and moment acting on a two-dimensional flat plate cascade which is harmonically oscillating in a subsonic flow field. The unsteady flow is considered to be a small perturbation to the uniform steady flow, with the steady flow assumed to separate at a specified fixed position on the airfoil suction surface. This formulation does not require the difference in the upwash velocity across the airfoil in the separated flow region to be determined before calculating the unsteady pressure difference across the chordline of the airfoils, thereby eliminating the assumption that the upwash difference is zero at the trailing edge when the steady flow is separated. Results obtained demonstrate that although flow separation decreases bending mode stability, it does not result in bending mode flutter. However, flow separation can result in torsion mode flutter, with this instability being a function of the location of both the separation point and the elastic axis.     

Communication during marital conflict: When couples alter their appraisal, they change their behavior.

In a sample of 77 recently married couples, within-person variance in cognitive appraisal was expected to predict corresponding within-person variance in communication behavior during conflict. Three types of appraisal were considered: expectancies of partner understanding, expectancies of partner negative communication, and attributions. Couples were observed in 4 different conflict conversations, completed during 2 assessment sessions, and appraisals were assessed prior to each conversation. Hierarchical linear modeling was used to analyze within-person effects. Changes from one conversation to the next in all 3 types of appraisal predicted corresponding within-person change in communication, and many effects were larger for wives than for husbands. Results were strongest for expectancies of partner understanding. Expectancies predicted change in one's own behavior after controlling for the accuracy of the expectancy. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Response of intraocular pressure to retrobulbar and peribulbar anesthesia

BACKGROUND AND OBJECTIVE: To evaluate the response of intraocular pressure (IOP) to retrobulbar and peribulbar anesthesia. PATIENTS AND METHODS: Patients were prospectively masked and randomized to receive either 4 cc of retrobulbar anesthesia (X = 29) or 6 cc of peribulbar anesthesia (X = 30), each consisting of a 50:50 mixture of 2% xylocaine and 0.75% bupivacaine with 150 units of hyaluronidase. IOPs were measured pre-anesthesia and 1, 2, and 5 minutes post-anesthesia in nonglaucoma patients undergoing cataract extraction and intraocular lens implantation. RESULTS: Mean IOPs in the retrobulbar group as determined with a tonometer were 18.24, 18.66, 19.14, and 17.86 mm Hg pre-anesthesia and 1, 2, and 5 minutes post-anesthesia, respectively. In the peribulbar group, the mean IOPs were 18.53, 21.20, 20.40, and 19.20 mm Hg, respectively. The 1-minute pressures in the two groups were statistically different (P = .023). Within the peribulbar group, the 1- and 2-minute pressures were statistically different from the pre-anesthesia IOP (P = .001 and P = .018, respectively). CONCLUSION: Peribulbar anesthesia, with its higher volume of anesthetic (6 vs 4 cc), results in a higher initial IOP. This difference was slight and short lived, and occurred in the absence of any external ocular compression. This study may have application in avoiding elevation of IOP in select patients undergoing a local procedure.     

Microchip-based purification of DNA from biological samples

A microchip solid-phase extraction method for purification of DNA from biological samples, such as blood, is demonstrated. Silica beads were packed into glass microchips and the beads immobilized with sol-gel to provide a stable and reproducible solid phase onto which DNA could be adsorbed. Optimization of the DNA loading conditions established a higher DNA recovery at pH 6.1 than 7.6. This lower pH also allowed for the flow rate to be increased, resulting in a decrease in extraction time from 25 min to less than 15 min. Using this procedure, template genomic DNA from human whole blood was purified on the microchip platform with the only sample preparation being mixing of the blood with load buffer prior to loading on the microchip device. Comparison between the microchip SPE (microchipSPE) procedure and a commercial microcentrifuge method showed comparable amounts of PCR-amplifiable DNA could be isolated from cultures of Salmonella typhimurium. The greatest potential of the microchipSPE device was illustrated by purifying DNA from spores from the vaccine strain of Bacillus anthracis, where eventual integration of SPE, PCR, and separation on a single microdevice could potentially enable complete detection of the infectious agent in less than 30 min.     

Controlled Nucleation of GaN Nanowires Grown with Molecular Beam Epitaxy

The location of GaN nanowires is controlled with essentially perfect selectivity using patterned SiN_x prior to molecular beam epitaxy growth. Nanowire growth is uniform within mask openings and absent on the mask surface for over 95% of the usable area of a 76 mm diameter substrate. The diameters of the resulting nanowires are controlled by the size of the mask openings. Openings of approximately 500 nm or less produce single nanowires with symmetrically faceted tips.     

A global collocation technique for the solution of opening mode crack problems

A review of various experimental and numerical techniques for determination of fracture mechanics calibration functions (i.e., the variation of K ₁ and CMOD with crack length) revealed that neither technique, employed independently, can determine K ₁, CMOD, and full field stresses in closed form over a wide range of crack lengths. To fill this void, a combined experimental/numerical collocation technique based on a series expansion of the modified Westergaard functions was developed. This technique uses both boundary conditions, known a priori, and interior stress field conditions, determined using a suitable experimental technique, for analysis of two dimensional, finite body, opening mode crack problems. This paper reports on an investigation of the accuracy of this technique and its sensitivity to errors in experimental data for a sample problem of practical interest.