Plant biomacromolecule delivery methods in the 21st century

The 21st century witnessed a boom in plant genomics and gene characterization studies through RNA interference and site-directed mutagenesis. Specifically, the last 15 years marked a rapid increase in discovering and implementing different genome editing techniques. Methods to deliver gene editing reagents have also attempted to keep pace with the discovery and implementation of gene editing tools in plants. As a result, various transient/stable, quick/lengthy, expensive (requiring specialized equipment)/inexpensive, and versatile/specific (species, developmental stage, or tissue) methods were developed. A brief account of these methods with emphasis on recent developments is provided in this review article. Additionally, the strengths and limitations of each method are listed to allow the reader to select the most appropriate method for their specific studies. Finally, a perspective for future developments and needs in this research area is presented.

A model to predict the histopathology of human stroke using diffusion and T2-weighted magnetic resonance imaging

BACKGROUND AND PURPOSE

We sought to identify MRI measures that have high probability in a short acquisition time to predict, at early time points after onset of ischemia, the eventual development of cerebral infarction in clinical patients who suffer occlusion of a cerebral artery.

METHODS

We developed an MR tissue signature model based on experimentally derived relationships of the apparent diffusion coefficient of water (ADCw) and T2 to ischemic brain tissue histopathology. In eight stroke patients we measured ADCw and T2 intensity using diffusion-weighted echo-planar imaging (DW-EPI). Tissue signature regions were defined, and theme maps of the ischemic focus at subacute time points after stroke onset were generated.

RESULTS

Five MR signatures were identified in human stroke foci: two that may predict either cell recovery or progression to necrosis, one that may mark the transition to cell necrosis, and two that may be markers of established cell necrosis.

CONCLUSIONS

An MR tissue signature model of ischemic histopathology using ADCw and T2 can now be tested for its potential to predict reversible and identify irreversible cellular damage in human ischemic brain regions.

Quantification of thallium-201 scintigrams in acute myocardial infarction

A method has been developed for measurement of myocardial infarct size from thallium-201 scintigrams that depends on computer measurement of levels of radioactivity in the myocardium. In 16 dogs, thallium-201 scintigrams were obtained in the left lateral and left anterior oblique projections 48 hours after ligation of the left anterior descending coronary artery. Scintigraphic results were obtained by two independent observers and were compared with tissue measurements of infarct volume calculated from thallium autoradiograms and nitro-blue tetrazolium (NBT)-stained tissue slices. Infarct volumes derived from tissue measurements were used to develop criteria for the computer scintigraphic technique. There was no significant difference in the scintigraphic measurements made by the two observers. Scintigraphic infarct size in the left lateral and left anterior oblique projections correlated with tissue infarct size with r values of 0.88 and 0.75, respectively, for thallium autoradiography and 0.71 and 0.70, respectively, for NBT tissue staining. The range of infarct volume was 3.3 to 14.8 percent of the left ventricular mass. Results of this study suggest that scintigraphic quantitation of infarct size is feasible in this dog model.