Heart-type fatty acid-binding protein reciprocally regulates glucose and fatty acid utilization during exercise

The role of heart-type cytosolic fatty acid-binding protein (H-FABP) in mediating whole body and muscle-specific long-chain fatty acid (LCFA) and glucose utilization was examined using exercise as a phenotyping tool. Catheters were chronically implanted in a carotid artery and jugular vein of wild-type (WT, n = 8), heterozygous (H-FABP(+/-), n = 8), and null (H-FABP(-/-), n = 7) chow-fed C57BL/6J mice, and mice were allowed to recover for 7 days. After a 5-h fast, conscious, unrestrained mice were studied during 30 min of treadmill exercise (0.6 mph). A bolus of [(125)I]-15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid and 2-deoxy-[(3)H]glucose was administered to obtain rates of whole body metabolic clearance (MCR) and indexes of muscle LCFA (R(f)) and glucose (R(g)) utilization. Fasting, nonesterified fatty acids (mM) were elevated in H-FABP(-/-) mice (2.2 +/- 0.9 vs. 1.3 +/- 0.1 and 1.3 +/- 0.2 for WT and H-FABP(+/-)). During exercise, blood glucose (mM) increased in WT (11.7 +/- 0.8) and H-FABP(+/-) (12.6 +/- 0.9) mice, whereas H-FABP(-/-) mice developed overt hypoglycemia (4.8 +/- 0.8). Examination of tissue-specific and whole body glucose and LCFA utilization demonstrated a dependency on H-FABP with exercise in all tissues examined. Reductions in H-FABP led to decreasing exercise-stimulated R(f) and increasing R(g) with the most pronounced effects in heart and soleus muscle. Similar results were seen for MCR with decreasing LCFA and increasing glucose clearance with declining levels of H-FABP. These results show that, in vivo, H-FABP has reciprocal effects on glucose and LCFA utilization and whole body fuel homeostasis when metabolic demands are elevated by exercise.     

What's in it for the companion animal? Pet attachment and college students' behaviors toward pets

Research on the human-nonhuman animal bond has focused primarily on its advantages to the human. The purpose of this study is to investigate behaviors of caregivers (owners) of companion animals (pets) and to examine the relationship between such behaviors and scores on a pet attachment scale. Participants were 501 largely nontraditional (older, married, employed full-time) college students living with a pet dog or cat. The study categorized owner behaviors as essential, standard, enriched, or luxury care. Almost all participants reported engaging in essential care behaviors, with numbers declining from category to category. Pet attachment scores appeared related to standard and enriched care behaviors but not to essential care. Too few participants reported doing luxury care behaviors to link them to attachment. The results suggest that even pet owners reporting low attachment provide beneficial care and attention to their pets and that pet attachment may be of limited use when looking at the benefit of the human-animal bond to the companion animal.     

Role of integrin-linked kinase in regulating phosphorylation of Akt and fibroblast survival in type I collagen matrices through a beta1 integrin viability signaling pathway

A beta1 integrin phosphatidylinositol 3-kinase/Akt pathway regulates fibroblast survival in collagen matrices. When fibroblasts attach to collagen, Akt becomes phosphorylated, providing a survival signal. In contrast, in response to mechanical forces generated during collagen contraction, Akt is dephosphorylated and fibroblasts undergo apoptosis. The kinase(s) responsible for regulating Akt phosphorylation in response to matrix-derived mechanical signals are unclear. Integrin-linked kinase (ILK) is associated with the beta1 integrin in the focal adhesion complex and as such is a candidate kinase that may regulate Akt phosphorylation and fibroblast viability. Nevertheless, there is no direct evidence that matrix-derived mechanical forces regulate cell viability by modulating ILK activity. Here, we show that ILK activity decreased in response to collagen matrix contraction, which correlated with Akt dephosphorylation and induction of fibroblast apoptosis. In contrast, enforced activation of beta1 integrin by activating antibody preserved ILK and Akt activity during collagen matrix contraction, and this is associated with protection from collagen contraction-induced apoptosis. Knock-down of ILK by small, interfering RNA (siRNA) attenuated Akt phosphorylation in response to ligation of beta1 integrin by collagen or activating antibody and enhanced fibroblast apoptosis in response to collagen contraction. Kinase dead ILK attenuated Akt phosphorylation and enhanced fibroblast apoptosis, whereas hyperactive and wild type ILK augmented Akt phosphorylation and protected fibroblasts from apoptosis. Constitutively active Akt preserved Akt activity and rescued ILK siRNA-treated fibroblasts from collagen contraction-induced apoptosis. These data establish that matrix-derived mechanical forces sensed by beta1 integrin are capable of modulating ILK activity which regulates fibroblast viability via an Akt-dependent mechanism.     

Reducing the stimulation of CD8+ T cells during infection with intracellular bacteria promotes differentiation primarily into a central (CD62LhighCD44high) subset

During infection with lymphocytic choriomeningitis virus, CD8(+) T cells differentiate rapidly into effectors (CD62L(low)CD44(high)) that differentiate further into the central memory phenotype (CD62L(high)CD44(high)) gradually. To evaluate whether this CD8(+) T cell differentiation program operates in all infection models, we evaluated CD8(+) T cell differentiation during infection of mice with recombinant intracellular bacteria, Listeria monocytogenes (LM) and Mycobacterium bovis (BCG), expressing OVA. We report that CD8(+) T cells primed during infection with the attenuated pathogen BCG-OVA differentiated primarily into the central subset that correlated to reduced attrition of the primed cells subsequently. CD8(+) T cells induced by LM-OVA also differentiated into central phenotype cells first, but the cells rapidly converted into effectors in contrast to BCG-OVA. Memory CD8(+) T cells induced by both LM-OVA as well as BCG-OVA were functional in that they produced cytokines and proliferated extensively in response to antigenic stimulation after adoptive transfer. During LM-OVA infection, if CD8(+) T cells were guided to compete for access to APCs, then they received reduced stimulation that was associated with increased differentiation into the central subset and reduced attrition subsequently. Similar effect was observed when CD8(+) T cells encountered APCs selectively during the waning phase of LM-OVA infection. Taken together, our results indicate that the potency of the pathogen can influence the differentiation and fate of CD8(+) T cells enormously, and the extent of attrition of primed CD8(+) T cells correlates inversely to the early differentiation of CD8(+) T cells primarily into the central CD8(+) T cell subset.     

Heme oxygenase-1 gene transfer inhibits angiotensin II-mediated rat cardiac myocyte apoptosis but not hypertrophy

Cardiac myocyte apoptosis underlies the pathophysiology of cardiomyopathy, and plays a critical role in the transition from myocardial hypertrophy to heart failure. Angiotensin II (Ang II) induces cardiac myocyte apoptosis and hypertrophy which contribute to heart failure possibly through enhanced oxidative stress; however, the mechanisms underlying the activation of both pathways and their interactions remain unclear. In the present study, we have investigated whether overexpression of the antioxidant protein heme oxygenase-1 (HO-1) protects against apoptosis and hypertrophy in cultured rat cardiac myocytes treated with Ang II. Our findings demonstrate that Ang II (100 nM, 24 h) alone upregulates HO-1 expression and induces both myocyte hypertrophy and apoptosis, assessed by measuring terminal deoxynucleotidyltransferase dUTP nick-end labelling (TUNEL) staining, caspase-3 activity and mitochondrial membrane potential. Ang II elicited apoptosis was augmented in the presence of tin protoporphyrin, an inhibitor of HO activity, while HO-1 gene transfer to myocytes attenuated Ang II-mediated apoptosis but not hypertrophy. Adenoviral overexpression of HO-1 was accompanied by a significant increase in Ang II induced phosphorylation of Akt, however, Ang II-mediated p38 mitogen activated protein kinase (MAPK) phosphorylation was attenuated. Inhibition of phosphotidylinositol-3-kinase enhanced myocyte apoptosis elicited by Ang II, however, p38MAPK inhibition had no effect, suggesting that overexpression of HO-1 protects myocytes via augmented Akt activation and not through modulation of p38MAPK activation. Our findings identify the signalling pathways by which HO-1 gene transfer protects against apoptosis and suggest that overexpression of HO-1 in cardiomyopathies may delay the transition from myocyte hypertrophy to heart failure.     

Influence of Polymer Seed Coatings, Soil Raking, and Time of Sowing on Seedling Performance in Post-Mining Restoration

This study represents part of a broader investigation into novel seed broadcasting methodologies as a means to optimize rehabilitation techniques following sand mining. Specifically, the study investigated the use of polymer seed coatings, time of sowing application, and in situ raking of the topsoil to optimize seedling recruitment to site. For polymer seed coatings, an ex situ trial was undertaken to evaluate seed coating effects on seedling emergence. Results demonstrated that seed coatings did not significantly inhibit maximum emergence percentage of 10 Banksia woodland species (out of 11 evaluated), but coated seeds from four species were on average 2–6 days slower to emerge than noncoated seeds. Seed coatings were found to have a greater effect in situ, with more coated seeds emerging than noncoated seeds. Topsoil raking (following seed sowing) and time of sowing were found to have the greatest impact on seedling emergence, with higher emergence following topsoil raking (5‐ to 90‐fold increase) and sowing in May (late autumn) (1.4‐ to 12‐fold increase) rather than in July (mid‐winter). The implications for mining rehabilitation are discussed, and areas for further research are considered.     

In vivo motion of the rectus femoris muscle after tendon transfer surgery

Rectus femoris transfer surgery is performed to convert the rectus femoris muscle from a knee extensor to a knee flexor. In this surgery, the distal tendon of the rectus femoris is detached from the patella and reattached to one of the knee flexor tendons. The outcomes of this procedure are variable, and it is not known if the surgery successfully converts the muscle to a knee flexor. We measured the motion of muscle tissue within the rectus femoris and vastus intermedius during knee extension in 10 unimpaired control subjects (10 limbs) and 6 subjects (10 limbs) after rectus femoris transfer using cine phase-contrast magnetic resonance imaging. Displacements of the vastus intermedius during knee extension were similar between control and tendon transfer subjects. In the control subjects, the rectus femoris muscle consistently moved in the direction of the knee extensors and displaced more than the vastus intermedius. The rectus femoris also moved in the direction of the knee extensors in the tendon transfer subjects; however, the transferred rectus femoris displaced less than the vastus intermedius. These results suggest that the rectus femoris is not converted to a knee flexor after its distal tendon is transferred to the posterior side of the knee, but its capacity for knee extension is diminished by the surgery.     

Divergent Functions Through Alternative Splicing: The Drosophila CRMP Gene in Pyrimidine Metabolism, Brain, and Behavior

DHP and CRMP proteins comprise a family of structurally similar proteins that perform divergent functions, DHP in pyrimidine catabolism in most organisms and CRMP in neuronal dynamics in animals. In vertebrates, one DHP and five CRMP proteins are products of six genes; however, Drosophila melanogaster has a single CRMP gene that encodes one DHP and one CRMP protein through tissue-specific, alternative splicing of a pair of paralogous exons. The proteins derived from the fly gene are identical over 90% of their lengths, suggesting that unique, novel functions of these proteins derive from the segment corresponding to the paralogous exons. Functional homologies of the Drosophila and mammalian CRMP proteins are revealed by several types of evidence. Loss-of-function CRMP mutation modifies both Ras and Rac misexpression phenotypes during fly eye development in a manner that is consistent with the roles of CRMP in Ras and Rac signaling pathways in mammalian neurons. In both mice and flies, CRMP mutation impairs learning and memory. CRMP mutant flies are defective in circadian activity rhythm. Thus, DHP and CRMP proteins are derived by different processes in flies (tissue-specific, alternative splicing of paralogous exons of a single gene) and vertebrates (tissue-specific expression of different genes), indicating that diverse genetic mechanisms have mediated the evolution of this protein family in animals.