MRI Features in a Canine Model of Ischemic Stroke: Correlation between Lesion Volume and Neurobehavioral Status during the Subacute Stage

The purpose of this study was to evaluate the diagnostic value of magnetic resonance imaging (MRI) and assess the correlation between the volume of the ischemic lesion and neurobehavioral status during the subacute stage of ischemic stroke. Ischemic stroke was induced in 6 healthy laboratory beagles through permanent occlusion of the middle cerebral artery (MCAO). T2-weighted and fluid-attenuated inversion recovery (FLAIR) imaging, diffusion-weighted imaging (DWI), measurement of the apparent diffusion coefficient (ADC) ratio, and neurobehavioral evaluation were performed 3 times serially by using a 1.5-T MR system: before and 3 and 10 d after MCAO. Ischemic lesions demonstrated T2 hyperintensity, FLAIR hyperintensity, and DWI hyperintensity. The ADC ratio was decreased initially but then was increased at 10 d after MCAO. Ischemic lesion volumes on T2-weighted and FLAIR imaging were not significantly different from those on DWI. The lesion volume and neurobehavioral score showed strong correlation. Our results suggest that conventional MRI may be a reliable diagnostic tool during the subacute stage of canine ischemic stroke.Abbreviations: ADC, apparent diffusion coefficient; DWI, diffusion-weighted imaging; FLAIR, fluid-attenuated inversion recovery; MCAO, middle cerebral artery occlusion; MRI, magnetic resonance imaging; PWI, perfusion-weighted imagingIn human medicine, stroke is a leading cause of adult mortality and neurologic disability worldwide.¹ Strokes previously were thought to be uncommon in small animals, but the true prevalence is unknown.⁴ These events are now recognized more frequently in dogs because of increased use of magnetic resonance imaging (MRI).^5,14,17Because the infusion of thrombolytic agents, such as urokinase or tissue plasminogen activator, within 3 to 6 h of the onset symptoms is effective in restoring blood flow and improving stroke outcome in humans,¹⁹ the detection of early ischemic changes is now thought to be necessary to improve patient outcome. Computed tomography and conventional MRI are not sufficiently sensitive to predict the presence and extent of ischemic damage during the acute stage after a stroke.^12,20 Therefore several MRI sequences, such as fluid-attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), and MR angiography, have been developed for early diagnosis and subsequent follow-up of ischemic stroke.³ High-field magnetic strengths (at least 1.5 T) are necessary to perform these sequences.In contrast to the situation in humans, ischemic stroke in many dogs is diagnosed during the subacute stage—24 h to 6 wk after the vascular insult—due to the time lag between the onset of clinical signs to referral and to the lack of standard diagnostic protocols for ischemic stroke in dogs. In most reports of strokes in dogs, the median interval between the onset of neurologic dysfunction and performance of an MRI was more than 2 d.^5,14,17 Whereas DWI has marked sensitivity to very early ischemic changes in the brain, T2-weighted and FLAIR images gradually become more hyperintense later (that is, during the first 24 h after the insult).³ Therefore, hyperintensity on T2-weighted and FLAIR images is believed to be representative of mature lesions.¹⁵ In light of these findings, we hypothesized that conventional MR sequences, such as T2-weighted and FLAIR imaging as well as DWI would be used for the diagnosis of the subacute stage of ischemic stroke in dogs.The purpose of this study was to evaluate the diagnostic value of MRI and assess the correlation between the volume of ischemic lesions and neurobehavioral status during the subacute stage of ischemic stroke in dogs. We therefore investigated the lesion volume of T2-weighted and FLAIR images compared with that on DWI images. Furthermore, we assessed the relationship between the apparent diffusion coefficient (ADC) of the ischemic lesions and the neurobehavioral status of the dogs.     

Morphological variation in the horse: defining complex traits of body size and shape

Horses, like many domesticated species, have been selected for broad variation in skeletal size. This variation is not only an interesting model of rapid evolutionary change during domestication, but is also directly applicable to the horse industry. Breeders select for complex traits like body size and skeletal conformation to improve marketability, function, soundness and performance in the show ring. Using a well-defined set of 35 measurements, we have identified and quantified skeletal variation in the horse species. We collected measurements from 1215 horses representing 65 breeds of diverse conformation such as the American Miniature, Shetland Pony, Arabian Horse, Thoroughbred, Shire and Clydesdale. Principal components analysis has identified two key dimensions of skeletal variation in the horse. Principal component 1 is positively correlated with every measurement and quantifies overall body size. Principal component 2 captures a pattern of bone widths vs. lengths and thus quantifies variation in overall bone thickness. By defining these complex skeletal traits, we have created a framework for whole genome association studies to identify quantitative trait loci that contribute to this variation.     

Functional Characterization of 14 Pht1 Family Genes in Yeast and Their Expressions in Response to Nutrient Starvation in Soybean

Background

Phosphorus (P) is essential for plant growth and development. Phosphate (Pi) transporter genes in the Pht1 family play important roles in Pi uptake and translocation in plants. Although Pht1 family genes have been well studied in model plants, little is known about their functions in soybean, an important legume crop worldwide.

Principal Findings

We identified and isolated a complete set of 14 Pi transporter genes (GmPT1-14) in the soybean genome and categorized them into two subfamilies based on phylogenetic analysis. Then, an experiment to elucidate Pi transport activity of the GmPTs was carried out using a yeast mutant defective in high-affinity Pi transport. Results showed that 12 of the 14 GmPTs were able to complement Pi uptake of the yeast mutant with Km values ranging from 25.7 to 116.3 µM, demonstrating that most of the GmPTs are high-affinity Pi transporters. Further results from qRT-PCR showed that the expressions of the 14 GmPTs differed not only in response to P availability in different tissues, but also to other nutrient stresses, including N, K and Fe deficiency, suggesting that besides functioning in Pi uptake and translocation, GmPTs might be involved in synergistic regulation of mineral nutrient homeostasis in soybean.

Conclusions

The comprehensive analysis of Pi transporter function in yeast and expression responses to nutrition starvation of Pht1 family genes in soybean revealed their involvement in other nutrient homeostasis besides P, which could help to better understand the regulation network among ion homeostasis in plants.     

Multi‐Length‐Scale Morphologies in PCPDTBT/PCBM Bulk‐Heterojunction Solar Cells

Additives are known to improve the performance of organic photovoltaic devices based on mixtures of a low bandgap polymer, poly[2,6‐(4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b′]‐dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadiazole)] (PCPDTBT) and [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM). The evolution of the morphology during the evaporation of the mixed solvent, which comprises additive and chlorobenzene (CB), is investigated by in‐situ grazing incidence X‐ray scattering, providing insight into the key role the additive plays in developing a multi‐length‐scale morphology. Provided the additive has a higher vapor pressure and a selective solubility for PCBM, as the host solvent (CB) evaporates, the mixture of the primary solvent and additive becomes less favorable for the PCPDTBT, while completely solubilizing the PCBM. During this process, the PCPDTBT first crystallizes into fibrils and then the PCBM, along with the remaining PCPDTBT, is deposited, forming a phase‐separated morphology comprising domains of pure, crystalline PCPDTBT fibrils and another domain that is a PCBM‐rich mixture with amorphous PCPDTBT. X‐ray/neutron scattering and diffraction methods, in combination with UV–vis absorption spectroscopy and transmission electron microscopy, are used to determine the crystallinity and phase separation of the resultant PCPDTBT/PCBM thin films processed with or without additives. Additional thermal annealing is carried out and found to change the packing of the PCPDTBT. The two factors, degree of crystallinity and degree of phase separation, control the multi‐length‐scale morphology of the thin films and significantly influence device performance.     

Molecular cloning and characterization of a novel human gene containing 4 ankyrin repeat domains

Ankyrin repeat, one of the most important protein motifs, plays a wide variety of roles in protein-protein interactions and in the signal pathways. Via large-scale sequencing, a novel 941-bp gene was isolated from an 18-week old human fetal brain cDNA library. It encodes a putative protein of 158 amino acid residues with four conserved ankyrin repeat domains. It displays a high degree of homology with rat low-density lipoprotein receptor-related protein 2-binding protein (Lrp2bp), and was therefore was named hLrp2bp (human Lrp2bp). The hLrp2bp gene was located in chromosome 4q35 and the conserved ankyrin repeat domains were located between amino acid residues 10 and 116. RT-PCR revealed that hLrp2bp was mainly expressed in the human testis, small intestine, colon and blood leukocytes, and in human pancreatic adenocarcinoma cells. A HEK293 cell was transfected with the ORF of hLrp2bp, and analyses showed that the protein was distributed both in the cytoplasm and nucleus.     

Influence of spatial structure on effective nutrient diffusion in bacterial biofilms

The main contribution of this paper is to use homogenization techniques to compute diffusion coefficients from experimental images of microbial biofilms. Our approach requires the analysis of several experimental spatial structures of biofilms in order to derive from them a Representative Volume Element (RVE). Then, we apply a suitable numerical procedure to the RVE to derive the diffusion coefficients. We show that diffusion coefficients significantly vary with the biofilm structure. These results suggest that microbial biofilm structures can favour nutrient access in some cases.     

Disruption of Ssp411 causes impaired sperm head formation and male sterility in mice

Background

We previously cloned the Ssp411 gene. We found that the Ssp411 protein is predominantly expressed in elongated spermatids in the rat testis in a stage-dependent manner. Although our findings strongly suggested that Ssp411 might play an important role in mammalian spermatogenesis, this hypothesis has not been studied.

Synergistic interactions between Glomus mosseae and Bradyrhizobium japonicum in enhancing proton release from nodules and hyphae

Soybean (Glycine max L. Merr.) seedlings were inoculated with Glomus mosseae (GM) and Bradyrhizobium japonicum (BJ) together or separately to study the effect of interactions on net H⁺ effluxes of nodules or extraradical hyphae by in vivo vibrating electrode techniques. GM promoted three-fold the H⁺ effluxes of nodules on mycorrhizal lateral roots and BJ increased eight-fold the net H⁺ effluxes of hyphae developing in the vicinity of nodules on lateral roots. Increments in plant P content were positively and linearly correlated with the net H⁺ efflux of nodules and hyphae. It is concluded that increased H⁺ effluxes of nodules resulted from enhanced nitrogenase activities induced by the presence of the AM fungus in lateral roots. The results point to additive effects of interactions between mycorrhizal fungi and rhizobia in increasing the extent of acidification of the “nodulesphere” and the hyposphere.