Calmodulin kinase II inhibition protects against myocardial cell apoptosis in vivo

Inhibition of the multifunctional Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) or depletion of sarcoplasmic reticulum (SR) Ca(2+) stores protects against apoptosis from excessive isoproterenol (Iso) stimulation in cultured ventricular myocytes, suggesting that CaMKII inhibition could be a novel approach to reducing cell death in conditions of increased adrenergic tone, such as myocardial infarction (MI), in vivo. We used mice with genetic myocardial CaMKII inhibition due to transgenic expression of a highly specific CaMKII inhibitory peptide (AC3-I) to test whether CaMKII was important for apoptosis in vivo. A second line of mice expressed a scrambled, inactive form of AC3-I (AC3-C). AC3-C and wild-type (WT) littermates were used as controls. AC3-I mice have reduced SR Ca(2+) content and are resistant to Iso- and MI-induced apoptosis compared with AC3-C and WT mice. Phospholamban (PLN) is a target for modulation of SR Ca(2+) content by CaMKII. PLN(-/-) mice have increased susceptibility to Iso-induced apoptosis. Verapamil pretreatment prevented Iso-induced apoptosis in PLN(-/-) mice, indicating the involvement of a Ca(2+)-dependent pathway. AC3-I and AC3-C mice were bred into a PLN(-/-) background. Loss of PLN increased and equalized SR Ca(2+) content in AC3-I, AC3-C, and WT mice and abolished the resistance to apoptosis in AC3-I mice after MI. There was a trend (P = 0.07) for increased Iso-induced apoptosis in AC3-I mice lacking PLN compared with AC3-I mice with PLN. These findings indicate CaMKII is proapoptotic in vivo and suggest that regulation of SR Ca(2+) content by PLN contributes to the antiapoptotic mechanism of CaMKII inhibition.     

A dynamic pathway for calcium-independent activation of CaMKII by methionine oxidation

tRNAs are synthesized as immature precursors, and on their way to functional maturity, extra nucleotides at their 5' ends are removed by an endonuclease called RNase P. All RNase P enzymes characterized so far are composed of an RNA plus one or more proteins, and tRNA 5' end maturation is considered a universal ribozyme-catalyzed process. Using a combinatorial purification/proteomics approach, we identified the components of human mitochondrial RNase P and reconstituted the enzymatic activity from three recombinant proteins. We thereby demonstrate that human mitochondrial RNase P is a protein enzyme that does not require a trans-acting RNA component for catalysis. Moreover, the mitochondrial enzyme turns out to be an unexpected type of patchwork enzyme, composed of a tRNA methyltransferase, a short-chain dehydrogenase/reductase-family member, and a protein of hitherto unknown functional and evolutionary origin, possibly representing the enzyme's metallonuclease moiety. Apparently, animal mitochondria lost the seemingly ubiquitous RNA world remnant after reinventing RNase P from preexisting components.     

Legacies in Switchgrass Resistance to and Recovery from Drought Suggest That Good Years Can Sustain Plants Through Bad Years

The warm-season perennial switchgrass (Panicum virgatum) is a candidate bioenergy crop. To be successful, switchgrass production must be maintained on low-quality landscapes with minimal inputs while facing future climates that are expected to be more extreme and more variable. We propose that antecedent rainfall constrains how plants respond to drought, as well as subsequently recover from drought. To test this idea, we examined how six switchgrass genotypes responded to a 1-year severe drought and then recovered under normal rainfall in the following year. These plants had previously grown for 3 years under a range of dry to wet rainfall levels in a shallow-soil common garden with no fertilizer. Plants previously exposed to drought produced less biomass, and basal area after the severe drought was relieved compared to previously well-watered plants. In addition, there were legacy effects caused by plant size: plants that were larger pre-drought were more likely to survive the severe drought, and plants that were larger during the severe drought recovered more biomass, basal area, and tillers post-drought. Although genotypes differed somewhat in their responses, the size constraint was consistent across genotypes. These findings suggest that we can establish more drought-resilient switchgrass stands by, for example, planning for initial irrigation or planting during a wet year to allow plants to grow larger prior to experiencing drought. Additional studies are needed to understand whether these rainfall and size legacies persist or are transient.     

Effect of slice thickness on brain magnetic resonance image texture analysis

Background  

The accuracy of texture analysis in clinical evaluation of magnetic resonance images depends considerably on imaging arrangements and various image quality parameters. In this paper, we study the effect of slice thickness on brain tissue texture analysis using a statistical approach and classification of T1-weighted images of clinically confirmed multiple sclerosis patients.     

Critical requirement for professional APCs in eliciting T cell responses to novel fragments of histidyl-tRNA synthetase (Jo-1) in Jo-1 antibody-positive polymyositis

Polymyositis (PM) is an autoimmune muscle disease characterized by oligoclonal T cell infiltrates mediating myocytotoxicity. Although antigenic triggers for this process remain undefined, clinically homogeneous subsets of PM patients are characterized by autoantibodies directed against nuclear and cytoplasmic Ags that include histidyl-tRNA synthetase (Jo-1). Available evidence suggests that formation of anti-Jo-1 autoantibodies is Ag-driven and therefore dependent on CD4(+) T cells that may also direct cytolytic CD8(+) T cells involved in myocyte destruction. To assess peripheral blood T cell responses to Jo-1, we first subcloned full-length human Jo-1 as well as novel fragments of Jo-1 into the maltose-binding protein expression vector pMALc2. Expressed proteins were then used in standard proliferation assays with either PBMC or autologous DCs as sources of APCs. Although PBMC-derived APCs and DCs both supported peripheral blood T cell proliferation when primed with full-length human Jo-1, only DCs promoted proliferative responses to a unique amino-terminal fragment of Jo-1. mAb blockade of different HLA Ags revealed that these responses were MHC class II dependent. Therefore, for the first time, these studies demonstrate anti-Jo-1 T cell responses in Jo-1 Ab-positive PM patients as well as in healthy control subjects. More importantly, this work underscores the critical importance of APC type in dictating T cell responses to a novel antigenic fragment of Jo-1.     

Ecoepidemiology,short history and control of Chagas disease in the endemic countries and the new challenge for non-endemic countries

Chagas disease is maintained in nature through the interchange of three cycles: the wild, peridomestic and domestic cycles. The wild cycle, which is enzootic, has existed for millions of years maintained between triatomines and wild mammals. Human infection was only detected in mummies from 4,000-9,000 years ago, before the discovery of the disease by Carlos Chagas in 1909. With the beginning of deforestation in the Americas, two-three centuries ago for the expansion of agriculture and livestock rearing, wild mammals, which had been the food source for triatomines, were removed and new food sources started to appear in peridomestic areas: chicken coops, corrals and pigsties. Some accidental human cases could also have occurred prior to the triatomines in peridomestic areas. Thus, triatomines progressively penetrated households and formed the domestic cycle of Chagas disease. A new epidemiological, economic and social problem has been created through the globalisation of Chagas disease, due to legal and illegal migration of individuals infected by Trypanosoma cruzi or presenting Chagas disease in its varied clinical forms, from endemic countries in Latin America to non-endemic countries in North America, Europe, Asia and Oceania, particularly to the United States of America and Spain. The main objective of the present paper was to present a general view of the interchanges between the wild, peridomestic and domestic cycles of the disease, the development of T. cruzi among triatomine, their domiciliation and control initiatives, the characteristics of the disease in countries in the Americas and the problem of migration to non-endemic countries.     

Regulation of [3H]nitrendipine binding by phospholipases A2 and C through direct and GTP-sensitive mechanisms.

We compared the effects of Phospholipases A2, C, B and D on [3H]nitrendipine binding to hamster cardiac membranes, in the absence and presence of ATP or GTP. Phospholipase A2, competitively inhibited [3H]nitrendipine binding to hamster cardiac membranes unchanged by ATP or GTP (Ki = 5 ng/ml); as evidenced by complete and reversible displacement of [3H]nitrendipine binding and increase in KD on Scatchard analyses. Phospholipase C also completely inhibited [3H]nitrendipine binding to hamster cardiac membranes (Ki = 5 micrograms/ml) with a decrease in Bmax and no change in KD on Scatchard analyses. The addition of GTP alone inhibited the PLC effect in EGTA-treated membranes. The addition of GTP with either CaCl2 or ATP or both resulted in an equal and opposite enhancement of the PLC effect. Phospholipases B and D had no effect on [3H]nitrendipine binding. These data support: (1) Direct effect of PLA2 on dihydropyridine binding. (2) Indirect regulation of dihydropyridine binding by Phospholipase C through a GTP and ATP-sensitive mechanism.     

MORPHOLOGICAL,ANATOMICAL, AND MOLECULAR CONSEQUENCES OF GROWTH AND DEVELOPMENT AT LOW TEMPERATURE IN SECALE CEREALE

Growth of winter cereals at low, nonfreezing temperatures is essential for the establishment of a cold-hardy state and subsequent survival of the overwintering plant. In this paper, I describe the consequences of growth and development of Secale cereale L. cv. Puma at cold-hardening temperatures with respect to leaf morphology, anatomy, and biochemistry, and with particular emphasis on their relationship to photosynthetic acclimation. Low temperature-induced structural and functional alterations at the level of ribulose bisphosphate carboxylase-oxygenase and the chloroplast thylakoid membrane are described and related to overall photosynthetic efficiency and capacity for CO₂ utilization. Growth and development at cold-hardening temperatures appear to result in changes in protein conformation and membrane organization, but not in basic composition. It is proposed that developmental temperature imparts a significant effect on the assembly of these multimeric, photosynthetic components, which leads to distinct structural and functional changes.