An Inverse Finite Element Method for Determining the Tissue Compressibility of Human Left Ventricular Wall during the Cardiac Cycle

The determination of the myocardium’s tissue properties is important in constructing functional finite element (FE) models of the human heart. To obtain accurate properties especially for functional modeling of a heart, tissue properties have to be determined in vivo. At present, there are only few in vivo methods that can be applied to characterize the internal myocardium tissue mechanics. This work introduced and evaluated an FE inverse method to determine the myocardial tissue compressibility. Specifically, it combined an inverse FE method with the experimentally-measured left ventricular (LV) internal cavity pressure and volume versus time curves. Results indicated that the FE inverse method showed good correlation between LV repolarization and the variations in the myocardium tissue bulk modulus K (K = 1/compressibility), as well as provided an ability to describe in vivo human myocardium material behavior. The myocardium bulk modulus can be effectively used as a diagnostic tool of the heart ejection fraction. The model developed is proved to be robust and efficient. It offers a new perspective and means to the study of living-myocardium tissue properties, as it shows the variation of the bulk modulus throughout the cardiac cycle.     

Review of recent research into cellulosic whiskers, their properties and their application in nanocomposite field

There are numerous examples where animals or plants synthesize extracellular high-performance skeletal biocomposites consisting of a matrix reinforced by fibrous biopolymers. Cellulose, the world's most abundant natural, renewable, biodegradable polymer, is a classical example of these reinforcing elements, which occur as whisker-like microfibrils that are biosynthesized and deposited in a continuous fashion. In many cases, this mode of biogenesis leads to crystalline microfibrils that are almost defect-free, with the consequence of axial physical properties approaching those of perfect crystals. This quite "primitive" polymer can be used to create high performance nanocomposites presenting outstanding properties. This reinforcing capability results from the intrinsic chemical nature of cellulose and from its hierarchical structure. Aqueous suspensions of cellulose crystallites can be prepared by acid hydrolysis of cellulose. The object of this treatment is to dissolve away regions of low lateral order so that the water-insoluble, highly crystalline residue may be converted into a stable suspension by subsequent vigorous mechanical shearing action. During the past decade, many works have been devoted to mimic biocomposites by blending cellulose whiskers from different sources with polymer matrixes.     

Spinal p38beta isoform mediates tissue injury-induced hyperalgesia and spinal sensitization

Antagonist studies show that spinal p38 mitogen-activated protein kinase plays a crucial role in spinal sensitization. However, there are two p38 isoforms found in spinal cord and the relative contribution of these two to hyperalgesia is not known. Here we demonstrate that the isoforms are distinctly expressed in spinal dorsal horn: p38alpha in neurons and p38beta in microglia. In lieu of isoform selective inhibitors, we examined the functional role of these two individual isoforms in nociception by using intrathecal isoform-specific antisense oligonucleotides to selectively block the expression of the respective isoform. In these rats, down-regulation of spinal p38beta, but not p38alpha, prevented nocifensive flinching evoked by intraplantar injection of formalin and hyperalgesia induced by activation of spinal neurokinin-1 receptors through intrathecal injection of substance P. Both intraplantar formalin and intrathecal substance P produced an increase in spinal p38 phosphorylation and this phosphorylation (activation) was prevented when spinal p38beta, but not p38alpha, was down-regulated. Thus, spinal p38beta, probably in microglia, plays a significant role in spinal nociceptive processing and represents a potential target for pain therapy.     

Localized Surface Plasmon Resonance (LSPR) Detection of Diphtheria Toxoid Using Gold Nanoparticle-Monoclonal Antibody Conjugates

Plasmonics - Detection of diphtheria toxin (DT) which is produced by Corynebacterium diphtheria, a zoonotic pathogen and a leading cause of diphtheria, is the critical step in the clinical...     

Toward understanding of rice innate immunity against Magnaporthe oryzae

The blast fungus, Magnaporthe oryzae, causes serious disease on a wide variety of grasses including rice, wheat and barley. The recognition of pathogens is an amazing ability of plants including strategies for displacing virulence effectors through the adaption of both conserved and variable pathogen elicitors. The pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) were reported as two main innate immune responses in plants, where PTI gives basal resistance and ETI confers durable resistance. The PTI consists of extracellular surface receptors that are able to recognize PAMPs. PAMPs detect microbial features such as fungal chitin that complete a vital function during the organism’s life. In contrast, ETI is mediated by intracellular receptor molecules containing nucleotide-binding (NB) and leucine rich repeat (LRR) domains that specifically recognize effector proteins produced by the pathogen. To enhance crop resistance, understanding the host resistance mechanisms against pathogen infection strategies and having a deeper knowledge of innate immunity system are essential. This review summarizes the recent advances on the molecular mechanism of innate immunity systems of rice against M. oryzae. The discussion will be centered on the latest success reported in plant–pathogen interactions and integrated defense responses in rice.     

Genetic,cytogenetic and morphological diversity in Helicrysum leucocephalum (Asteraceae) populations

Helichrysum (family Asteraceae) is a large, heterogeneous and polyphyletic genus. Most of the Helichrysum species have ornamental and medicinal values. Helicrysum leucocephalum Boiss., has wide geographical distribution in Iran and forms several local populations. The present investigation was performed to study inter populations, genetic, cytogenetic and morphological diversity of this medicinal species. The AMOVA test showed significant genetic difference among the studied populations but the Mantel test did not show correlation between the genetic distance and geographical distance of these populations. STRUCTURE and reticulation analyses showed some degree of genetic admixture and gene exchange among the studied populations. These populations had different chromosome numbers and also differed significantly in the size of their chromosomes.     

Locomotor function shapes the passive mechanical properties and operating lengths of muscle

Locomotor muscles often perform diverse roles, functioning as motors that produce mechanical energy, struts that produce force and brakes that dissipate mechanical energy. In many vertebrate muscles, these functions are not mutually exclusive and a single muscle often performs a range of mechanically diverse tasks. This functional diversity has obscured the relationship between a muscle''s locomotor function and its mechanical properties. I use hopping in toads as a model system for comparing muscles that primarily produce mechanical energy with muscles that primarily dissipate mechanical energy. During hopping, hindlimb muscles undergo active shortening to produce mechanical energy and propel the animal into the air, whereas the forelimb muscles undergo active lengthening to dissipate mechanical energy during landing. Muscles performing distinct mechanical functions operate on different regions of the force–length curve. These findings suggest that a muscle''s operating length may be shaped by potential trade-offs between force production and sarcomere stability. In addition, the passive force–length properties of hindlimb and forelimb muscles vary, suggesting that passive stiffness functions to restrict the muscle''s operating length in vivo. These results inform our understanding of vertebrate muscle variation by providing a clear link between a muscle''s locomotor function and its mechanical properties.     

Evaluation of Alginate/Chitosan nanoparticles as antisense delivery vector: Formulation,optimization and in vitro characterization

Nanoparticles comprising Alginate/Chitosan polymers were prepared by pregel preparation method through drop wise addition of various concentrations of CaCl₂ to a defined concentration of Sodium Alginate. Then, Chitosan/Antisense solution with a certain N/P ratio was added to the pregel to make the nanoparticles. The effect of such parameters as polymer ratio, CaCl₂/Alginate ratio and N/P ratio on the particle size distribution and loading efficacy was studied. The optimum conditions were 1:1 (w/w) Alginate to Chitosan ratio, 0.2% CaCl₂/Alginate ratio and N/P ratio of 5 at pH 5.3. The resulting nanoparticles had a loading efficacy of 95.6% and average size of 194 nm as confirmed by PCS method and SEM images showed spherical and smooth particles. The zeta potential of optimized nanoparticles prepared by this method was about +30 mV which could result in good stability of nanoparticles during manipulation and storage.     

Factors that influence decisions by families to donate brain tissue for medical research

Whilst mainstream transplant literature provides valuable insights into the influences on families to donate organs and tissues for transplant, the relevance of these findings in relation to organ donation for research remain speculative. The present study aims to expand the research donation literature, by exploring factors that influence a family’s decision to donate brain tissue to neuroscience research. The verbal responses of the senior available next-of-kin (NOK), to the question of brain donation for research, are analysed. The donation rate was high (54%) over the 5-year-period. NOK relationship to the deceased, and post mortem interval were the main factors associated with a positive donation. Parents were most likely to donate and this may result from a lifetime of decision-making on behalf of the deceased. Also, the longer the interval between death of the potential donor and the question being asked, the greater the likelihood of donation.