Effect of supplementall-tyrosine on pigment production in cultures of the Legionnaires' disease bacterium

The etiologic agent of Legionnaires' disease grows on certain agar media. Cultures of this organism on supplemented Mueller-Hinton agar are characterized by the appearance of brown pigment in and around areas of bacterial growth. The major peptone source in Mueller-Hinton agar is an acid hydrolysate of casein. Legionnaires' disease bacterium also grows on a medium in which the peptone source is 0.25% yeast extract, but no pigment is produced. If the yeast extract agar is enriched withl-tyrosine, pigment formation can occur. Pigmentation of cultures of Legionnaires' disease bacterium may be mediated by a phenolo-monooxygenase, or tyrosinase.     

Pyridostigmine improves cardiac function and rhythmicity through RyR2 stabilization and inhibition of STIM1-mediated calcium entry in heart failure

Heart failure (HF) is characterized by asymmetrical autonomic balance. Treatments to restore parasympathetic activity in human heart failure trials have shown beneficial effects. However, mechanisms of parasympathetic-mediated improvement in cardiac function remain unclear. The present study examined the effects and underpinning mechanisms of chronic treatment with the cholinesterase inhibitor, pyridostigmine (PYR), in pressure overload HF induced by transverse aortic constriction (TAC) in mice. TAC mice exhibited characteristic adverse structural (left ventricular hypertrophy) and functional remodelling (reduced ejection fraction, altered myocyte calcium (Ca) handling, increased arrhythmogenesis) with enhanced predisposition to arrhythmogenic aberrant sarcoplasmic reticulum (SR) Ca release, cardiac ryanodine receptor (RyR2) hyper-phosphorylation and up-regulated store-operated Ca entry (SOCE). PYR treatment resulted in improved cardiac contractile performance and rhythmic activity relative to untreated TAC mice. Chronic PYR treatment inhibited altered intracellular Ca handling by alleviating aberrant Ca release and diminishing pathologically enhanced SOCE in TAC myocytes. At the molecular level, these PYR-induced changes in Ca handling were associated with reductions of pathologically enhanced phosphorylation of RyR2 serine-2814 and STIM1 expression in HF myocytes. These results suggest that chronic cholinergic augmentation alleviates HF via normalization of both canonical RyR2-mediated SR Ca release and non-canonical hypertrophic Ca signaling via STIM1-dependent SOCE.     

Transcriptional profiling of peripheral blood mononuclear cells in pancreatic cancer patients identifies novel genes with potential diagnostic utility

Background

It is well known that many malignancies, including pancreatic cancer (PC), possess the ability to evade the immune system by indirectly downregulating the mononuclear cell machinery necessary to launch an effective immune response. This knowledge, in conjunction with the fact that the trancriptome of peripheral blood mononuclear cells has been shown to be altered in the context of many diseases, including renal cell carcinoma, lead us to study if any such alteration in gene expression exists in PC as it may have diagnostic utility.

Methods and Findings

PBMC samples from 26 PC patients and 33 matched healthy controls were analyzed by whole genome cDNA microarray. Three hundred eighty-three genes were found to be significantly different between PC and healthy controls, with 65 having at least a 1.5 fold change in expression. Pathway analysis revealed that many of these genes fell into pathways responsible for hematopoietic differentiation, cytokine signaling, and natural killer (NK) cell and CD8+ T-cell cytotoxic response. Unsupervised hierarchical clustering analysis identified an eight-gene predictor set, consisting of SSBP2, Ube2b-rs1, CA5B, F5, TBC1D8, ANXA3, ARG1, and ADAMTS20, that could distinguish PC patients from healthy controls with an accuracy of 79% in a blinded subset of samples from treatment naïve patients, giving a sensitivity of 83% and a specificity of 75%.

Conclusions

In summary, we report the first in-depth comparison of global gene expression profiles of PBMCs between PC patients and healthy controls. We have also identified a gene predictor set that can potentially be developed further for use in diagnostic algorithms in PC. Future directions of this research should include analysis of PBMC expression profiles in patients with chronic pancreatitis as well as increasing the number of early-stage patients to assess the utility of PBMCs in the early diagnosis of PC.     

Population variables and life-history characteristics of the alligator pipefish Syngnathoides biaculeatus, in Papua New Guinea

Population structure and life-history variables of the widely distributed alligator pipefish Syngnathoides biaculeatus were characterized in Bootless Bay, Papua New Guinea over the course of 11 months. There was little evidence of seasonality with four focal populations showing no significant change in abundance. Similarly, the sex ratio remained 1:1 for all but 1 month. Reproductive males carrying eggs (148–278 mm in total length, L _T) were found in all months. Brood size was significantly, positively related to male L _T for newly laid broods only. Maximum observed brood size was 351 and mean ± s . d . brood size was 238 ± 57 for newly laid broods. Juveniles and males showed no change in mean L _T over the year while slightly smaller females were captured in November 2006 and September 2007. Males were significantly longer than females so von Bertalanffy growth coefficients were estimated separately for each sex: males L _∞= 285 mm, K = 0·82 year⁻¹ and females L _∞= 261 mm, K = 1·10 year⁻¹. These estimates suggest that this species grows rapidly and has a short-life span. In the context of growing concern about overexploitation of syngnathids, a rapid growth rate combined with year round reproductive activity suggests that the tropical S. biaculeatus may be relatively resilient with regard to fishing pressure.     

Current status of molecular markers for early detection of sporadic pancreatic cancer

Pancreatic cancer (PC) is a highly lethal malignancy with near 100% mortality. This is in part due to the fact that most patients present with metastatic or locally advanced disease at the time of diagnosis. Significantly, in nearly 95% of PC patients there is neither an associated family history of PC nor of diseases known to be associated with an increased risk of PC. These groups of patients who comprise the bulk of PC cases are termed as "sporadic PC" in contrast to the familial PC cases that comprise only about 5% of all PCs. Given the insidious onset of the malignancy and its extreme resistance to chemo and radiotherapy, an abundance of research in recent years has focused on identifying biomarkers for the early detection of PC, specifically aiming at the sporadic PC cohort. However, while several studies have established that asymptomatic individuals with a positive family history of PC and those with certain heritable syndromes are candidates for PC screening, the role of screening in identifying sporadic PC is still an unsettled question. The present review attempts to assess this critical question by investigating the recent advances made in molecular markers with potential use in the early diagnosis of sporadic PC - the largest cohort of PC cases worldwide. It also outlines a novel yet simple risk factor based stratification system that could be potentially employed by clinicians to identify those individuals who are at an elevated risk for the development of sporadic PC and therefore candidates for screening.     

Cytolytic and phospholipase C activity in Legionella species

To examine one possible mechanism of damage to leucocytes and tissue cells in legionellosis, seven species of Legionella were examined for cytolytic activity and for elaboration of phospholipase C, an enzyme that can damage mammalian cell membranes. Cytolysis was assessed using erythrocytes in agar. Phospholipase C was assayed by release of p-nitrophenol from p-nitrophenylphosphorylcholine and of tritiated phosphorylcholine from L-alpha-dipalmitoyl-[choline-methyl-3H]phosphatidylcholine. L. pneumophila, L. bozemanii, L. micdadei, L. dumoffii, L. gormanii, L. longbeachae and L. jordanis all lysed dog red blood cells, which have a high ratio of membrane phosphatidylcholine to sphingomyelin. The same strains hydrolysed varying amounts of p-nitrophenylphosphorylcholine; L. bozemanii exhibited the greatest activity. L. pneumophila, L. bozemanii, L. dumoffii, L. longbeachae and L. jordanis, but not L. micdadei, released tritiated phosphorylcholine from labelled substrate. These results indicate that several species of Legionella possess cytolytic capability; exotoxins with activity may play a role.     

A phospholipase C from the Dallas 1E strain of Legionella pneumophila serogroup 5: purification and characterization of conditions for optimal activity with an artificial substrate

Phospholipase C from the Dallas 1E strain of Legionella pneumophila serogroup 5 was purified from buffered yeast extract culture supernate by ion-exchange chromatography followed by fractionation by manganous chloride and ammonium sulphate precipitation steps. Enzyme activity was assayed by hydrolysis of p-nitrophenylphosphorylcholine and confirmed by release of radioactivity from tritiated L-alpha-dipalmitoylphosphatidylcholine labelled in the methyl groups of choline. After SDS-PAGE, the purified preparation yielded a single band upon Coomassie-blue staining. This protein migrated with an apparent Mr of 50,000-54,000. Phospholipase C activity was maximal at pH greater than or equal to 8.4 and was enhanced in the presence of sorbitol and of several nonionic detergents but was eliminated by SDS. EDTA, Cu2+, Fe2+ and Zn2+ inhibited enzyme activity, whereas Ba2+, Ca2+, Co2+, Mg2+ and Mn2+ restored activity to EDTA-treated material. No haemolytic activity was demonstrated with the purified enzyme.     

Inhibition of Aβ42 aggregation using peptides selected from combinatorial libraries

Increasing evidence suggests that the aggregation of the small peptide Aβ42 plays an important role in the development of Alzheimer's disease. Inhibiting the initial aggregation of Aβ42 may be an effective treatment for preventing, or slowing, the onset of the disease. Using an in vivo screen based on the enzyme EGFP, we have searched through two combinatorially diverse peptide libraries to identify peptides capable of inhibiting Aβ42 aggregation. From this initial screen, three candidate peptides were selected and characterized. ThT studies indicated that the selected peptides were capable of inhibiting amyloid aggregation. Additional ThT studies showed that one of the selected peptides was capable of disaggregating preformed Aβ42 fibers. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.