MnSOD antisense treatment and exercise-induced protection against arrhythmias

Exercise provides protection against ischemia-reperfusion (I-R)-induced arrhythmias, myocardial stunning, and infarction. An exercise-induced increase in myocardial manganese superoxide dismutase (MnSOD) activity has been reported to be vital for protection against infarction. However, whether MnSOD is essential for exercise-induced protection against ventricular arrhythmias is unknown. We determined the effects of preventing the exercise-induced increase in MnSOD activity on arrhythmias during I-R resulting in myocardial stunning. Male rats remained sedentary or were subjected to successive bouts of endurance exercise. During in vivo myocardial I-R, the incidence of arrhythmias was significantly lower in the exercise-trained rats than in the sedentary rats as evidenced by the arrhythmia. When exercised rats were pretreated with antisense oligonucleotides directed against MnSOD, protection from arrhythmias was attenuated. Moreover, I-R resulted in significant increases in nitro-tyrosine (NT) in the sedentary group. Exercise abolished this I-R-induced NT formation but this protection was unchanged by antisense treatment. Protein carbonyls were increased by I-R, but neither exercise nor antisense treatment impacted carbonyl formation. These data demonstrate that an exercise-induced increase in MnSOD activity is important for protection against arrhythmias. The mechanism by which MnSOD provides protection does not appear to be linked to protein nitrosylation or oxidation.     

Extracellular signal-regulated kinase and phosphoinositol-3 kinase mediate IGF-1 induced proliferation of fetal sheep cardiomyocytes

Growth of the fetal heart involves cardiomyocyte enlargement, division, and maturation. Insulin-like growth factor-1 (IGF-1) is implicated in many aspects of growth and is likely to be important in developmental heart growth. IGF-1 stimulates the IGF-1 receptor (IGF1R) and downstream signaling pathways, including extracellular signal-regulated kinase (ERK) and phosphoinositol-3 kinase (PI3K). We hypothesized that IGF-1 stimulates cardiomyocyte proliferation and enlargement through stimulation of the ERK cascade and stimulates cardiomyocyte differentiation through the PI3K cascade. In vivo administration of Long R3 IGF-1 (LR3 IGF-1) did not stimulate cardiomyocyte hypertrophy but led to a decreased percentage of cells that were binucleated in vivo. In culture, LR3 IGF-1 increased myocyte bromodeoxyuridine (BrdU) uptake by three- to five-fold. The blockade of either ERK or PI3K signaling (by UO-126 or LY-294002, respectively) completely abolished BrdU uptake stimulated by LR3 IGF-1. LR3 IGF-1 did not increase footprint area, but as expected, phenylephrine stimulated an increase in binucleated cardiomyocyte size. We conclude that 1) IGF-1 through IGF1R stimulates cardiomyocyte division in vivo; hyperplastic growth is the most likely explanation of IGF-1 stimulated heart growth in vivo; 2) IGF-1 through IGF1R does not stimulate binucleation in vitro or in vivo; 3) IGF-1 through IGF1R does not stimulate hypertrophy either in vivo or in vitro; and 4) IGF-1 through IGF1R requires both ERK and PI3K signaling for proliferation of near-term fetal sheep cardiomyocytes in vitro.     

First report of a natural hybrid between Schistosoma mansoni and S. rodhaini

Experimental crosses between Schistosoma mansoni and S. rodhaini have shown that hybrid offspring are viable, yet, until now, no naturally occurring hybrid has been identified. A collection of freshwater snails from Nyamlebi-Ngoma, Ukerewe Island, Lake Victoria, Tanzania, yielded a mixed infection within a single Biomphalaria sudanica of S. mansoni females and S. mansoni-S. rodhaini hybrid males. The hybrids were identified using deoxyribonucleic acid (DNA) sequences. Mitochondrial DNA 16S and 12S sequences of the hybrids match those of S. mansoni, whereas their nuclear ribosomal DNA ITS1 and ITS2 sequences match those of S. rodhaini. The identification of hybrids in Tanzania highlights the possibility that the genetic identity of either parasite species might be modified by introgression.     

Enzymic synthesis,chemical characterisation and Sda activity of GalNAcß1-4[NeuAcα2-3]Galß1-4GlcNAc and GalNAcß1-4[NeuAcα2-3]Galß1-4Glc

The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and¹H-500 MHz NMR spectroscopy. In Sd^a serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity.     

Ultra-deep sequencing reveals the microRNA expression pattern of the human stomach

Background

While microRNAs (miRNAs) play important roles in tissue differentiation and in maintaining basal physiology, little is known about the miRNA expression levels in stomach tissue. Alterations in the miRNA profile can lead to cell deregulation, which can induce neoplasia.

Methodology/Principal Findings

A small RNA library of stomach tissue was sequenced using high-throughput SOLiD sequencing technology. We obtained 261,274 quality reads with perfect matches to the human miRnome, and 42% of known miRNAs were identified. Digital Gene Expression profiling (DGE) was performed based on read abundance and showed that fifteen miRNAs were highly expressed in gastric tissue. Subsequently, the expression of these miRNAs was validated in 10 healthy individuals by RT-PCR showed a significant correlation of 83.97% (P<0.05). Six miRNAs showed a low variable pattern of expression (miR-29b, miR-29c, miR-19b, miR-31, miR-148a, miR-451) and could be considered part of the expression pattern of the healthy gastric tissue.

Conclusions/Significance

This study aimed to validate normal miRNA profiles of human gastric tissue to establish a reference profile for healthy individuals. Determining the regulatory processes acting in the stomach will be important in the fight against gastric cancer, which is the second-leading cause of cancer mortality worldwide.     

Targeting the Cell Stress Response of Plasmodium falciparum to Overcome Artemisinin Resistance

Successful control of falciparum malaria depends greatly on treatment with artemisinin combination therapies. Thus, reports that resistance to artemisinins (ARTs) has emerged, and that the prevalence of this resistance is increasing, are alarming. ART resistance has recently been linked to mutations in the K13 propeller protein. We undertook a detailed kinetic analysis of the drug responses of K13 wild-type and mutant isolates of Plasmodium falciparum sourced from a region in Cambodia (Pailin). We demonstrate that ART treatment induces growth retardation and an accumulation of ubiquitinated proteins, indicative of a cellular stress response that engages the ubiquitin/proteasome system. We show that resistant parasites exhibit lower levels of ubiquitinated proteins and delayed onset of cell death, indicating an enhanced cell stress response. We found that the stress response can be targeted by inhibiting the proteasome. Accordingly, clinically used proteasome inhibitors strongly synergize ART activity against both sensitive and resistant parasites, including isogenic lines expressing mutant or wild-type K13. Synergy is also observed against Plasmodium berghei in vivo. We developed a detailed model of parasite responses that enables us to infer, for the first time, in vivo parasite clearance profiles from in vitro assessments of ART sensitivity. We provide evidence that the clinical marker of resistance (delayed parasite clearance) is an indirect measure of drug efficacy because of the persistence of unviable parasites with unchanged morphology in the circulation, and we suggest alternative approaches for the direct measurement of viability. Our model predicts that extending current three-day ART treatment courses to four days, or splitting the doses, will efficiently clear resistant parasite infections. This work provides a rationale for improving the detection of ART resistance in the field and for treatment strategies that can be employed in areas with ART resistance.     

Inflammatory Bowel Disease and Risk of Adverse Pregnancy Outcomes

Background and Objectives

Existing data on pregnancy complications in inflammatory bowel disease (IBD) are inconsistent. To address these inconsistencies, we investigated potential associations between IBD, IBD-related medication use during pregnancy, and pregnancy loss, pre-eclampsia, preterm delivery, Apgar score, and congenital abnormalities.

Methods

We conducted a cohort study in >85,000 Danish National Birth Cohort women who were pregnant in the period 1996-2002 and had information on IBD, IBD-related medication use (systemic or local corticosteroids, 5-aminosalicylates), pregnancy outcomes and potential confounders. We evaluated associations between IBD and adverse pregnancy/birth outcomes using Cox regression and log-linear binomial regression.

Results

IBD was strongly and significantly associated with severe pre-eclampsia, preterm premature rupture of membranes and medically indicated preterm delivery in women using systemic corticosteroids during pregnancy (hazard ratios [HRs] >7). IBD was also associated with premature preterm rupture of membranes in women using local corticosteroid medications (HR 3.30, 95% confidence interval [CI] 1.33-8.20) and with medically indicated preterm delivery (HR 1.91, 95% CI 0.99-3.68) in non-medicated women. Furthermore, IBD was associated with low 5-minute Apgar score in term infants (risk ratio [RR] 2.19, 95% CI 1.03-4.66). Finally, Crohn’s disease (but not ulcerative colitis) was associated with major congenital abnormalities in the offspring (RR 1.85, 95% CI 1.06-3.21). No child with a congenital abnormality born to a woman with IBD was exposed to systemic corticosteroids in utero.

Conclusion

Women with IBD are at increased risk of severe pre-eclampsia, medically indicated preterm delivery, preterm premature rupture of membranes, and delivering infants with low Apgar score and major congenital malformations. These associations are only partly explained by severe disease as reflected by systemic corticosteroid use.     

Structural characterization of a ribose-5-phosphate isomerase B from the pathogenic fungus Coccidioides immitis

Background

F-spondin is a multi-domain extracellular matrix (ECM) protein and a contact-repellent molecule that directs axon outgrowth and cell migration during development. The reelin_N domain and the F-spondin domain (FS domain) comprise a proteolytic fragment that interacts with the cell membrane and guides the projection of commissural axons to floor plate. The FS domain is found in F-spondins, mindins, M-spondin and amphiF-spondin.

Results

We present the crystal structure of human F-spondin FS domain at 1.95Å resolution. The structure reveals a Ca²⁺-binding C2 domain variant with an 8-stranded antiparallel β-sandwich fold. Though the primary sequences of the FS domains of F-spondin and mindin are less than 36% identical, their overall structures are very similar. The unique feature of F-spondin FS domain is the presence of three disulfide bonds associated with the N- and C-termini of the domain and a highly conserved N-linked glycosylation site. The integrin-binding motif found in mindin is not conserved in the F-spondin FS domain.

Conclusion

The structure of the F-spondin FS domain completes the structural studies of the multiple-domain ECM molecule. The homology of its core structure to a common Ca²⁺- and lipid-binding C2 domain suggests that the F-spondin FS domain may be responsible for part of the membrane targeting of F-spondin in its regulation of axon development. The structural properties of the FS domain revealed in this study pave the way for further exploration into the functions of F-spondin.