High-Resolution Harmonics Ultrasound Imaging for Non-Invasive Characterization of Wound Healing in a Pre-Clinical Swine Model

This work represents the first study employing non-invasive high-resolution harmonic ultrasound imaging to longitudinally characterize skin wound healing. Burn wounds (day 0-42), on the dorsum of a domestic Yorkshire white pig were studied non-invasively using tandem digital planimetry, laser speckle imaging and dual mode (B and Doppler) ultrasound imaging. Wound depth, as measured by B-mode imaging, progressively increased until day 21 and decreased thereafter. Initially, blood flow at the wound edge increased up to day 14 and subsequently regressed to baseline levels by day 21, when the wound was more than 90% closed. Coinciding with regression of blood flow at the wound edge, there was an increase in blood flow in the wound bed. This was observed to regress by day 42. Such changes in wound angiogenesis were corroborated histologically. Gated Doppler imaging quantitated the pulse pressure of the primary feeder artery supplying the wound site. This pulse pressure markedly increased with a bimodal pattern following wounding connecting it to the induction of wound angiogenesis. Finally, ultrasound elastography measured tissue stiffness and visualized growth of new tissue over time. These studies have elegantly captured the physiological sequence of events during the process of wound healing, much of which is anticipated based on certain dynamics in play, to provide the framework for future studies on molecular mechanisms driving these processes. We conclude that the tandem use of non-invasive imaging technologies has the power to provide unprecedented insight into the dynamics of the healing skin tissue.     

Powerful Tests for Multi-Marker Association Analysis Using Ensemble Learning

Multi-marker approaches have received a lot of attention recently in genome wide association studies and can enhance power to detect new associations under certain conditions. Gene-, gene-set- and pathway-based association tests are increasingly being viewed as useful supplements to the more widely used single marker association analysis which have successfully uncovered numerous disease variants. A major drawback of single-marker based methods is that they do not look at the joint effects of multiple genetic variants which individually may have weak or moderate signals. Here, we describe novel tests for multi-marker association analyses that are based on phenotype predictions obtained from machine learning algorithms. Instead of assuming a linear or logistic regression model, we propose the use of ensembles of diverse machine learning algorithms for prediction. We show that phenotype predictions obtained from ensemble learning algorithms provide a new framework for multi-marker association analysis. They can be used for constructing tests for the joint association of multiple variants, adjusting for covariates and testing for the presence of interactions. To demonstrate the power and utility of this new approach, we first apply our method to simulated SNP datasets. We show that the proposed method has the correct Type-1 error rates and can be considerably more powerful than alternative approaches in some situations. Then, we apply our method to previously studied asthma-related genes in 2 independent asthma cohorts to conduct association tests.     

Immature frontal lobe contributions to cognitive control in children: evidence from fMRI.

Event-related fMRI was employed to characterize differences in brain activation between children ages 8-12 and adults related to two forms of cognitive control: interference suppression and response inhibition. Children were more susceptible to interference and less able to inhibit inappropriate responses than were adults. Effective interference suppression in children was associated with prefrontal activation in the opposite hemisphere relative to adults. In contrast, effective response inhibition in children was associated with activation of posterior, but not prefrontal, regions activated by adults. Children failed to activate a region in right ventrolateral prefrontal cortex that was recruited for both types of cognitive control by adults. Thus, children exhibited immature prefrontal activation that varied according to the type of cognitive control required.     

Molecular docking analysis of phytocompounds from Acacia farnesiana with protein targets linked to bronchitis

Acute bronchitis is a lower respiratory tract lung infection that causes bronchial inflammation. The known protein drug targets are peptidoglycan D, D-transpeptidase, and DNA topoisomerase 4 subunit A for bronchitis linked infections. These are the membrane associated macromolecules which takes a major role in the formation of cell wall membrane by synthesising the cross-linked peptidoglycan. Therefore, it is of interest to design molecules with improved binding features with these protein targets. Hence, we document the molecular docking analysis data of four phytocompounds from Acacia farnesiana having optimal binding features with these targets linked to bronchitis for further consideration.     

Cryoenzymic studies on myosin subfragment 1: perturbation of an enzyme reaction by temperature and solvent

The effects of temperature and solvent on myosin subfragment 1 ATPase have been studied. Under all of the conditions used the data could be fitted to the Bagshaw - Trentham pathway: (formula; see text) Ethylene glycol (40%) was used as the cryosolvent ; this makes K1 and k+2 measurable and allows for temperature studies over an extensive temperature range (+35 to -20 degrees C) and thus to reasonably accurate thermodynamic parameters. The following techniques were used: ATP chase (for K1 and k+2); Pi burst (k+2 or k+3 + k-3); single-turnover Pi burst [k0 = k +4K3 /(1 + K3)] absorption stopped flow (k+2 or k+3 + k-3); steady state (k+6 or k0). Myosin provides examples of causes for nonlinear Arrhenius and van't Hoff plots. A temperature-induced structural change is exemplified by a "jump" in an Arrhenius plot of k+2 and "breaks" in van't Hoff plots of K1 and K3. A change in rate-limiting step is illustrated from stopped-flow experiments ( kobsd approximately k+2 at low and approximately k+3 + k-3 at high temperatures) and steady-state experiments (kcat approximately k+6 at low and approximately k0 at high temperatures). A third cause is illustrated by k0: an Arrhenius plot of k0 is nonlinear since there is a break in K3. These studies illustrate the use of temperature perturbation as a way of revealing reaction intermediates and of defining the conditions required for the isolation of a particular intermediate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Kinetics of the allosteric transition of aspartate transcarbamylase. Chemical quench studies

Using a chemical quench device, the rate of synthesis of carbamyl aspartate from the substrates aspartate and carbamyl phosphate was followed as a function of the time between mixing the enzyme with substrates and quenching with trichloroacetic acid. This function, which is linear at long times, shows (at 4 degrees C) a transient lag phase of product of roughly 10 ms. However, when the catalytic subunit (in which the enzymatic activity is desensitized) is used instead of the enzyme, the lag disappears. Therefore the lag seems to be associated with the control functions of the enzyme, i.e. to represent the allosteric transition involved in substrate-substrate (homotropic) co-operativity. Thus the relaxation time for the activation process is roughly 10 ms. The implications of these results are examined.     

Initiation of Spore Germination in Glycolytic Mutants of Bacillus subtilis

Enzyme activities of glycolysis and glyconeogenesis are present in spores of Bacillus subtilis, the rate-limiting step of glucose (GLC) metabolism being its phosphorylation. GLC allows initiation of germination in the presence of fructose (FRU) and asparagine (ASN), not because it is used via the Embden-Meyerhof path, but because it is oxidized in the nonphosphorylated form via the spore-specific GLC dehydrogenase. Spores of mutants lacking GLC-phosphoenolpyruvate transferase, FRU-6-P-kinase, or phosphoglucoisomerase activity can still be initiated by the above substrate combination. Furthermore, GLC can be replaced by 2-deoxy-GLC, which is also oxidized by GLC-dehydrogenase, but not by α- or β-methylglucoside, which are not substrates of this enzyme. GLC probably acts by reducing nicotinamide adenine dinucleotide (or nicotinamide adenine dinucleotide phosphate), which is used for some metabolic reaction other than the cytochrome-linked electron transport system, since inhibitors of this system do not inhibit initiation. Spores of a mutant lacking FRU-1-P-kinase activity can no longer be initiated by GLC+FRU+ASN, but they do respond to the combination of GLC+mannose+ASN. Since spores of a FRU-6-P-kinase (or phosphoglucoisomerase) mutant can still respond to either FRU or mannose, FRU-6-P (or some derivative) apparently is needed for initiation (in addition to reduced nicotinamide adenine dinucleotide and an amino donor). Alanine can initiate germination in spores of all of the above mutants, indicating that it can form all required compounds. However, in a mutant lacking P-glycerate kinase activity, alanine initiates only after a long lag and at a slow rate, indicating that some compound in the upper metabolic subdivision is required for initiation, in agreement with the above findings. All initiating agents of B. subtilis probably produce the same required compound(s) by different metabolic routes.     

Use of interposed polytetrafluorethylene (PTFE) graft in distal splenorenal shunt

Two patients with massive upper gastrointestinal hemorrhages required transsplenic decompression of the esophageal varices, but because technical difficulties precluded tension-free anastomoses, interposition of PTFE grafts was used to solve these difficult situations.