The type IV pilin,PilA, is required for full virulence of <Emphasis Type="Italic">Francisella tularensis</Emphasis> subspecies <Emphasis Type="Italic">tularensis</Emphasis>

Background  

All four Francisella tularensis subspecies possess gene clusters with potential to express type IV pili (Tfp). These clusters include putative pilin genes, as well as pilB, pilC and pilQ, required for secretion and assembly of Tfp. A hallmark of Tfp is the ability to retract the pilus upon surface contact, a property mediated by the ATPase PilT. Interestingly, out of the two major human pathogenic subspecies only the highly virulent type A strains have a functional pilT gene.     

Assessment of fertility protection and ovarian reserve with GnRH antagonist in rats undergoing chemotherapy with cyclophosphamide

Background  

Reproductive function following chemotherapy is of increasing importance given that survival rates are improving. We assessed whether a gonadotropin-releasing hormone antagonist (GnRHant; cetrorelix) could promote ovarian protection against damage due to chemotherapy.     

Cocaine-induced oxidative stress precedes cell death in human neuronal progenitor cells

By 2003, an estimated 34 million Americans had used cocaine according to the National Survey on Drug Use & Health. About 5.9 million of those had used in the past 12 months. Chronic cocaine users often develop addiction, dependency and tolerance to the drug. The psychological and physical effects of cocaine are due to the disruption of the limbic system in the central nervous system (CNS). Increased oxidative stress reported in the frontal cortex and the striatum of rats exposed to cocaine suggests that oxidative damage plays a significant role in cocaine-induced disruption of the CNS. Although it is evident that cocaine induces oxidative stress in the CNS, little has been learned about whether such increased oxidative stress is also relevant to apoptosis in cocaine-exposed models. To gain insight into the role of cocaine-induced oxidative stress in apoptosis, we hypothesized that oxidative stress precedes cell death when cocaine is administrated. To test this hypothesis, we have monitored the oxidative stress and apoptotic effects of acute cocaine exposure in human neuronal progenitor cells (HNPC). We found that oxidative stress was significantly increased at 48h after a 30min cocaine exposure compared to control cells, and that this was followed by cell death at 72h. Using the same experimental paradigm we have previously shown that pro-inflammatory genes are up-regulated in cocaine-exposed HNPC at 24h. Therefore, we suggest that the increased oxidative stress (possibly mediated by inflammatory responses) precedes cell death in cocaine-exposed HNPC. This may have implications for the consequences of cocaine abuse in situations where antioxidant capacity is compromised, as in the aging brain.     

Temporal transmission studies of mouse parvovirus 1 in BALB/c and C.B-17/Icr-Prkdc(scid) mice

Fecal shedding and transmission of mouse parvovirus 1 (MPV) to naive sentinels, breeding mates, and progeny were assessed. Neonatal SCID and BALB/c mice inoculated with MPV were evaluated over 24 wk; several mice from each strain were mated once during this period. Fecal MPV loads for each cage were determined weekly by quantitative polymerase chain reaction (PCR) analysis, and all mice were evaluated by quantitative PCR analysis of lymphoid tissues and seroconversion to MPV antigens in immunocompetent mice. Results indicated persistently high fecal shedding of MPV in SCID mice throughout the evaluation period sufficient to allow transmission to sentinels, naive breeding partners, and the progeny of infected male mice and naive partners. Lymphoid tissue viral loads in the progeny of infected female SCID mice were high at weaning but low at 6 wk of age. Infected BALB/c mice shed high levels of MPV in feces for 3 wk postinoculation, with seroconversion only in sentinels exposed during the first 2 wk postinoculation. Thereafter the feces of infected BALB/c mice and the lymphoid tissues of sentinels, naive breeding partners, and progeny intermittently contained extremely low levels of MPV DNA. Although pregnancy and lactation did not increase viral shedding in BALB/c mice, MPV exposure levels were sufficient to induce productive infection in some BALB/c progeny. These data indicate that the adaptive immune response suppresses, but does not eliminate, MPV shedding; this suppression is sufficient to inhibit infection of weanling and adult mice but allows productive infection of some progeny.     

Proteome changes in bovine longissimus thoracis muscle during the early postmortem storage period

Postmortem changes in protein composition up to 24 h in bovine longissimus thoracis muscle were investigated by two-dimensional gel electrophoresis and MALDI-TOF MS/MS. A total of 47 spots were significantly changed the first 24 h postmortem. The 39 identified proteins can be divided into five groups: metabolic enzymes, defense and stress proteins, structural proteins, proteolytic enzymes, and unclassified proteins. The identified metabolic enzymes are all associated with ATP-generating pathways, either the glycolytic pathway or energy metabolism. In addition, several defense and stress proteins were changed in abundance in this study. These findings contribute to a better understanding of the biochemical processes during postmortem storage of meat.     

ADP Ribosylation Factor 6 (ARF6) Promotes Acrosomal Exocytosis by Modulating Lipid Turnover and Rab3A Activation

Regulated secretion is a central issue for the specific function of many cells; for instance, mammalian sperm acrosomal exocytosis is essential for egg fertilization. ARF6 (ADP-ribosylation factor 6) is a small GTPase implicated in exocytosis, but its downstream effectors remain elusive in this process. We combined biochemical, functional, and microscopy-based methods to show that ARF6 is present in human sperm, localizes to the acrosomal region, and is required for calcium and diacylglycerol-induced exocytosis. Results from pulldown assays show that ARF6 exchanges GDP for GTP in sperm challenged with different exocytic stimuli. Myristoylated and guanosine 5′-3-O-(thio)triphosphate (GTPγS)-loaded ARF6 (active form) added to permeabilized sperm induces acrosome exocytosis even in the absence of extracellular calcium. We explore the ARF6 signaling cascade that promotes secretion. We demonstrate that ARF6 stimulates a sperm phospholipase D activity to produce phosphatidic acid and boosts the synthesis of phosphatidylinositol 4,5-bisphosphate. We present direct evidence showing that active ARF6 increases phospholipase C activity, causing phosphatidylinositol 4,5-bisphosphate hydrolysis and inositol 1,4,5-trisphosphate-dependent intra-acrosomal calcium release. We show that active ARF6 increases the exchange of GDP for GTP on Rab3A, a prerequisite for secretion. We propose that exocytic stimuli activate ARF6, which is required for acrosomal calcium efflux and the assembly of the membrane fusion machinery. This report highlights the physiological importance of ARF6 as a key factor for human sperm exocytosis and fertilization.     

Potential Zoonotic Trematodes Recovered in Stray Cats from Kuwait Municipality,Kuwait

Stray cats are a common feature roaming the streets and alleys of Kuwait; they could be a source of parasites, including trematodes, that affect humans. A survey was conducted to identify feline trematodes and throw the light on their public health significance in Kuwait. Out of 240 stray cats trapped from different localities of Kuwait from June 2011 to May 2012, 59 (24.6%) were found to be infected with 14 species of trematodes. The most common were trematodes of the genus Heterophyes, particularly H. heterophyes and H. dispar that were found in respectively 15.8% and 10.8% of the cats examined. Other trematodes recorded, with lower prevalences, were Heterophyes nocens (2.9%), Haplorchis taichui (3.8%), Stictodora sawakinensis (2.1%), Stellantchasmus falcatus (1.6%), Echinochasmus japonicus (1.6%), and Mesostephanus dottrensi (1.3%). Centrocestus cuspidatus, Galactosomum fregatae, Ascocotyle sp., Mesostephanus appendiculatus, Haplorchis yokogawai, and Pygidiopsis genata showed the lowest prevalence (0.4%) and intensity. The majority of the trematodes are recorded for the first time in Kuwait and even in the Gulf region. The study reveals that stray cats are good indicators of fish-borne trematodes in the environment. As all trematodes recovered are zoonotic, their significance to public health should be considred.