bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of rpoS in the survival of Escherichia coli in the viable but non‐culturable state
Authors: Boaretti Marzia , Del Mar Lleò Maria , Bonato Barbara , Signoretto Caterina , Canepari Pietro 
Published: September 2003

SummaryWhen exposed to stress‐provoking environmental conditions such as those of ground waters, many medically important bacteria have been shown to be capable of activating a survival strategy known as the viable but non‐culturable (VBNC) state. In this state bacteria are no longer culturable on conventional growth media, but the cells maintain their viability and pathogenicity genes/factors and can start dividing again, in a part of the cell population, upon restoration of favourable environmental conditions. Little is known about the genetic mechanisms underlying the VBNC state. In this study we show evidence of involvement of the rpoS gene in persistence of Escherichia coli in the VBNC state. The kinetics of entry into the non‐culturable state and duration of cell viability were measured in two E. coli mutants carrying an inactivated rpoS gene and compared with those of the parents. For these experiments, laboratory microcosms consisting of an artificial oligotrophic medium incubated at 4°C were used. The E. coli parental strains reached the non‐culturable state in 33 days when the plate counts were evaluated on Luria–Bertani agar containing sodium pyruvate, whereas cells of the rpoS mutants lost their culturability in only 21 days. Upon reaching unculturability the parents yielded respiring cells and cells with intact membranes for at least the next three weeks and resuscitation was allowed during this time. In contrast, the RpoS‐ mutant cells demonstrated intact membranes for only two weeks and a very restricted (<7 days) resuscitation capability. Guanosine 3′,5′‐bispyrophosphate (ppGpp) acts as a positive regulator during the production and functioning of RpoS. A mutant deficient in ppGpp production behaved like the rpoS mutants, while overproducers of ppGpp displayed a vitality at least comparable to that of RpoS+ strains. These results suggest that the E. coli parental strains enter the VBNC state which lasts for, at least, three weeks, after which apparently all the cells die. The rpoS mutants do not activate this survival strategy and early die. This implies involvement of the rpoS gene in E. coli persistence in the VBNC state.
Persistence of adhesive properties in Vibrio cholerae after long‐term exposure to sea water
Authors: Pruzzo Carla , Tarsi Renato , Del Mar Lleò Maria , Signoretto Caterina , Zampini Massimiliano , Pane Luigi , Colwell Rita R. , Canepari Pietro 
Published: September 2003

SummaryThe effect of exposure to artificial sea water (ASW) on the ability of classical Vibrio cholerae O1 cells to interact with chitin‐containing substrates and human intestinal cells was studied. Incubation of vibrios in ASW at 5°C and 18°C resulted in two kinds of cell responses: the viable but non‐culturable (VBNC) state (i.e. <0.1 colony forming unit ml−1) at 5°C, and starvation (i.e. maintenance of culturability of the population) at 18°C. The latter remained rod shaped and, after 40 days’ incubation, presented a 47–58% reduction in the number of cells attached to chitin, a 48–53% reduction in the number of bacteria adhering to copepods, and a 48–54% reduction in the number of bacteria adhering to human cultured intestinal cells, compared to control cells not suspended in ASW. Bacteria suspended in ASW at 5°C became coccoid and, after 40 days, showed 34–42% fewer cells attached to chitin, 52–55% fewer adhering to copep‐ods, and 45–48% fewer cells adhering to intestinal cell monolayers, compared to controls. Sarkosyl‐insoluble membrane proteins that bind chitin particles were isolated and analysed by SDS‐PAGE. After 40 days incubation in ASW at both 5°C and 18°C vibrios expressed chitin‐binding ligands similar to bacteria harvested in the stationary growth phase. It is concluded that as vibrios do not lose adhesive properties after long‐term exposure to ASW, it is important to include methods for VBNC bacteria when testing environmental and clinical samples for purposes of public health safety.
Enduring toxicity of transgenic Anabaena PCC 7120 expressing mosquito larvicidal genes from Bacillus thuringiensis ssp. israelensis†
Authors: Manasherob Robert , Otieno‐Ayayo Zachariah Ngalo , Ben‐Dov Eitan , Miaskovsky Rina , Boussiba Sammy , Zaritsky Arieh 
Published: September 2003

SummaryPersistence of biological control agents against mosquito larvae was tested under simulated field conditions. Mosquito larvicidal activity of transgenic Anabaena PCC 7120 expressing cry4Aa, cry11Aa and p20 from Bacillus thuringiensis ssp. israelensis was greater than B. thuringiensis ssp. israelensis primary powder (fun 89C06D) or wettable powder (WP) (Bactimos products) when either mixed with silt or exposed to sunlight outdoors. Reduction of Bactimos primary powder toxicity was at least 10‐fold higher than Anabaena’s after mixing with silt. In outdoors experiments, Bactimos WP remained toxic (over 30% mortality of 3rd instar Aedes aegypti larvae) for 2–4 days only, while transgenic Anabaena’s toxicity endured 8–21 days.
The influence of antibiotic production and pre‐emptive colonization on the population dynamics of Pantoea agglomerans (Erwinia herbicola) Eh1087 and Erwinia amylovora in planta
Authors: Giddens Stephen R. , Houliston Gary J. , Mahanty H. Khris 
Published: September 2003

SummaryStigma colonization by Erwinia amylovora is the crucial first step in the development of most fire blight infections in apple and pear trees. Suppression at this point of the disease process by antagonists of E. amylovora, such as Pantoea agglomerans (Erwinia herbicola) strain Eh1087, is a rational approach to control fire blight. We tested the hypothesis that the ability of E. amylovora to compete with Eh1087 for colonization of a stigma is reduced by the potential for Eh1087 to produce the phenazine antibiotic, d‐alanylgriseoluteic acid (AGA). In competition experiments on the stigmas of apple flowers, E. amylovora was significantly less successful against Eh1087 (AGA+) than against EhΔAGA (AGA‐). Further experiments to test the importance of pre‐emptive colonization of the stigma by either the pathogen or the antagonist suggested that AGA production significantly enhanced the competitiveness of Eh1087 when it was applied at the same time or 24 h before the pathogen. We also found that pre‐emptive stigma colonization by either the pathogen or the antagonist resulted in a population that was resilient to subsequent invasion by a second species suggesting that niche exclusion has a dominant influence on the dynamics of bacterial populations on stigmas.
A strain isolated from gas oil‐contaminated soil displays chemotaxis towards gas oil and hexadecane
Authors: Lanfranconi Mariana P. , Alvarez Héctor M. , Studdert Claudia A. 
Published: September 2003

SummaryIn this report we describe the isolation of a strain from soil contaminated with gas oil by taking bacteria from a chemotactic ring on gas oil‐containing soft agar plates. Partial 16 S rDNA sequencing of the isolated strain showed 99.1% identity with Flavimonas oryzihabitans. It was not only able to degrade different aliphatic hydrocarbons but it was also chemotactic towards gas oil and hexadecane, as demonstrated by the use of three different chemotaxis methods, such as agarose plug and capillary assays and swarm plate analysis. In addition, the strain was chemotactic to a variety of carbon sources that serve as growth substrates, including glucose, arabinose, mannitol, glycerol, gluconate, acetate, succinate, citrate, malate, lactate and casaminoacids. This is the first report on chemotaxis of a hydrocarbon‐degrading bacterium towards a pure alkane, such as hexadecane.The fact that environmental isolates show chemotaxis towards contaminant/s present in the site of isolation suggests that chemotaxis might enhance biodegradation by favouring contact between the degrading microorganism and its substrate.
Leitbakteria of microbial biofilm communities causing occlusion of biliary stents
Authors: Wenderoth Dirk F. , Ferslev Björn , Macarri Giampiero , Molinari Gabriella , Lünsdorf Heinrich , Timmis Kenneth N. 
Published: September 2003

SummaryBiliary stents inserted to relieve obstructive jaundice caused by biliary or pancreatic malignancies inevitably become occluded by microbial growth in the form of diverse microbial community biofilms. The scarce information available on these communities is based on cultivation methods, but such methods usually provide distorted overviews of community composition, so commonalities and differences in biliary stent communities are uncertain. We extracted DNA and RNA from the microbial communities of 11 biliary stents explanted from nine patients in hospitals from two different countries, amplified 16S rRNA and rDNA sequences, analysed the amplicons by the single‐strand conformation polymorphism (SSCP) method, and sequenced and deduced phylogenetic assignments of the major amplicons representing the major biofilm community members. We used a Modified Robbins Device (MRD) to study de novo development of a stent biofilm from a patient stent microbial community. Single‐strand conformation polymorphism fingerprinting revealed the same six abundant bacterial species, here designated Leitbakteria, namely Klebsiella pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, Enterobacter aerogenes, and two unculturable bacteria distantly related to E. coli and Shigella sonnei, in all of the stent biofilm communities. In the experimental biliary stent system, a sequential colonization of the stent surface was observed, with P. aeruginosa being the pioneer colonizer, followed by K. pneumoniae and one of the unculturable Leitbakteria, followed by the remainder of the community. The overview of microbial biofilm communities of biliary stents gained by the use of culture‐independent methods revealed new unculturable bacteria as major members of biliary stent biofilms, and the diversity of the abundant members of the stent biofilms is considerably lower than suggested from earlier studies based on cultivation methods, and that communities from different stents from different patients in different countries are remarkably similar and have similar major members, the stent Leitbakteria.
Inhibitors of swelling‐activated chloride channels increase infarct size and apoptosis in rabbit myocardium
Authors: Souktani Rachid , Ghaleh Bijan , Tissier Renaud , De Tassigny Alexandra d'Anglemont , Aouam Karim , Bedossa Pierre , Charlemagne Danièle , Samuel Janelyse , Henry Patrick , Berdeaux Alain 
Published: September 2003

AbstractApoptosis is a significant contributor to myocardial cell death during ischemia‐reperfusion and swelling‐activated chloride channels (ICl,swell) contribute to apoptosis. However, the relationship between ICl,swell, ischemia‐reperfusion and apoptosis remains unknown. To further investigate this, New Zealand rabbits underwent a 20‐min coronary artery occlusion (CAO) followed by 72 h of coronary artery reperfusion (CAR). Two ICl,swell blockers, 5‐nitro‐2‐[3‐phenylpropylamino]benzoic acid (NPPB) and indanyloxyacetic acid 94 (IAA‐94) (both 1 mg/kg), were administered prior to CAO and throughout the 72 h CAR. Infarct size (IS) was increased with NPPB and IAA‐94 compared with control (vehicle) rabbits (51 ± 2% and 48 ± 3% and vs. 35 ± 2%, respectively, P < 0.05). Similar results were found when NPPB was administered only during the reperfusion period. The percentage of TUNEL‐positive nuclei in the border zone of the infarct was increased with NPPB compared with control (37 ± 2% vs. 25 ± 3%, P < 0.05) as well as the number of cytoplasmic histone‐associated DNA fragments (0.45 ± 0.06 vs. 0.33 ± 0.04 absorbance units, P < 0.05). These findings support the concept that ICl,swell channels play an important role in the determination of myocardial infarct size and apoptosis during ischemia‐reperfusion.
Assessing immunotoxicity: guidelines
Authors: Putman E. , van der Laan J.W. , van Loveren H. 
Published: September 2003

AbstractOver the last couple of years the assessment of immunotoxic potential of human pharmaceuticals has drawn considerable attention worldwide. Regulatory agencies entrusted with the registration of pharmaceuticals (or other compounds) found an increased need for guidance on this issue. This has resulted in the release of guidance documents on immunotoxicity in Europe, USA and Japan in close succession. In Europe the CPMP has released their immunotoxicity guidance documents that are now in force. The FDA and the Japanese Authorities are in the process of doing so, and will shortly enforce them.Immune suppression and stimulation, hypersensitivity, photosensitivity, drug‐induced autoimmunity and developmental immunotoxicity are the focus of regulatory testing. This review discusses these kinds of immunotoxicity and their clinical implications. The three regional guidelines and screening tools for detection are discussed. Additionally, the scientific background on which these guidelines are based is briefly highlighted.
Activation of DNA biosynthesis in human hepatoblastoma HEPG2 cells by the nitric oxide donor, sodium nitroprusside
Authors: Sokołowska Maria , Rokita Hanna , Włodek Lidia 
Published: September 2003

AbstractThe role of nitric oxide (NO) in carcinogenesis is controversial as it has been shown to both stimulate and inhibit tumour growth. Also, there are contradictory opinions regarding the effects of NO on the proliferation of normal and tumour cells. The aim of our study was to use an in vitro model to determine the influence of exogenous NO donors on DNA biosynthesis by measuring [3H] thymidine incorporation in human hepatoblastoma cells (HepG2). The studies were conducted with the following NO precursors: sodium nitroprusside (SNP), S‐nitrosoglutathione, and nitroglycerine (NTG). Out of all three NO donors, SNP increased NO levels and strongly stimulated DNA biosynthesis. A SNP concentration of 150 μm induced optimal NO levels necessary for the activation of DNA biosynthesis. Lower levels of DNA biosynthesis (118% increase over the control) were observed in the presence of NTG, whereas S‐nitrosoglutathione had no effect. Antioxidants such as thiol‐containing drugs, N‐acetylcysteine and tocopherol, proved to be the most efficient co‐activators of SNP‐induced DNA synthesis. On the other hand, supplementing the SNP‐containing medium with compounds that induce oxidative stress and lower the level of –SH groups such as hydrogen peroxide, doxorubicin, and N‐ethylmaleimide, led to the inhibition of DNA synthesis. Therefore, our results firmly confirm the hypothesis that biological effects of exogenous NO donors depends on the redox status of the cell.
Neuroprotection assessment by topographic electroencephalographic analysis: effects of a sodium channel blocker to reduce polymorphic delta activity following ischaemic brain injury in rats
Authors: Williams Anthony J. , Lu Xi‐Chun M. , Hartings Jed A. , Tortella Frank C. 
Published: September 2003

AbstractThe spatiotemporal electroencephalogram (EEG) pathology associated with brain injury was studied using high‐resolution, 10‐electrode cortical EEG mapping in a rat model of middle cerebral artery occlusion (MCAo). Using this model we evaluated the ability of the novel sodium channel blocker and neuroprotective agent RS100642 to resolve injury‐induced EEG abnormalities as a measure of neurophysiological recovery from brain injury. The middle cerebral artery (MCA) was occluded for 1 h during which a dramatic loss of EEG power was measured over the injured cortex with near complete recovery upon reperfusion of blood to the MCA region in all rats. The resultant progression of the MCAo/reperfusion injury (6–72 h) included the appearance of diffuse polymorphic delta activity (PDA), as visually indicated by the presence of high‐amplitude slow‐waves recorded from both brain hemispheres. PDA was associated with large increases in EEG power, particularly evident in outer ‘peri‐infarct’ regions of the ipsilateral parietal cortex as visualized using topographic EEG mapping. Post‐injury treatment with RS100642 (1.0 mg/kg, i.v.) significantly reduced the PDA activity and attenuated the increase in EEG power throughout the course of the injury. These effects were associated with a reduction in brain infarct volume and improved neurological function. These methods of EEG analysis may be helpful tools to evaluate the physiological recovery of the brain from injury in humans following treatment with an experimental neuroprotective compound.
Inhibition of l‐arginine transport by reactive oxygen species in rat anococcygeus muscle
Authors: Tugba Durlu N. , Burcin Ismailoglu U. , Sahin‐Erdemli Inci 
Published: September 2003

AbstractThe effect of l‐arginine on nitrergic transmission and its alteration with reactive oxygen species (ROS) were investigated. l‐arginine potentiated the relaxation response induced by electrical field stimulation in rat anococygeus muscle. This effect was inhibited by l‐lysine, a cationic amino acid using y+L and y+ transport systems in a similar way with l‐arginine. The neutral amino acid l‐leucine, which uses only y+L system as a transport mechanism, inhibited this potentiation at only low frequency stimulation. Electrolysis of the physiological solution did not change the responses to electrical field stimulation, but inhibited the potentiation elicited by l‐arginine that was prevented in the presence of mannitol and N‐acetyl‐l‐cysteine.In conclusion, l‐arginine is transported via y+ system predominantly to potentiate the relaxation response to nitrergic nerve stimulation in rat anococcygeus muscle. ROS, primarily hydroxyl radicals inhibited l‐arginine‐induced potentiation probably by interacting with the y+ amino acid transport system.
Role of nitric oxide in the CBF autoregulation during acute stage after subarachnoid haemorrhage in rat pial artery
Authors: Cho Hyun Gee , Shin Hwa Kyoung , Shin Yung Woo , Lee Jeong Hyun , Hong Ki Whan 
Published: September 2003

AbstractThe present study was aimed to identify whether endogenously produced nitric oxide (NO) plays a role in preservation of cerebral blood flow (CBF) autoregulation in rat pial artery during the acute stage after subarachnoid haemorrhage (SAH). During the acute stage after SAH, the lower limit of CBF autoregulation significantly shifted to the higher arterial blood pressure in association with suppressed vasodilatation in response to acute hypotension, which was accompanied by significantly increased expression of endothelial nitric oxide synthase mRNA and increased production of superoxide anion in cerebral vessels. SAH‐induced increase in superoxide production was further enhanced under pretreatment with N‐nitro‐l‐arginine methyl ester in the cerebral vessels. Following additional administration of l‐arginine (100 mg/kg, i.p.), the haemodynamic alterations were significantly restored in association with significantly reduced superoxide level in the cerebral vessels. In line with these findings, rats that received polyethylene glycol superoxide dismutase and catalase or Mn(III) tetrakis (4‐benzoic acid) porphyrin chloride showed recovery of impaired autoregulatory vasodilation in response to acute hypotension. Thus, it is suggested that NO endogenously produced is importantly implicated in the preservation of CBF autoregulation during the acute stage after SAH via its capability to scavenge superoxide anion.
Increased adrenergic contractility and decreased mRNA expression of NOS III in aging rat urinary bladders
Authors: Lluel P. , Palea S. , Ribière P. , Barras M. , Teillet L. , Corman B. 
Published: September 2003

AbstractOur objective was to study age‐related changes in adrenergic contractility and gene expression profile in the rat urinary bladder. Young (3‐month old), adult (10‐month old) and senescent (30‐month old) male WAG/Rij rats were used. Gene expression profile in the rat urinary bladder was defined using AtlasTM microarray technology. In vitro contractile responses induced by KCl, phenylephrine (PHE) and norepinephrine (NE) were compared in isolated urinary bladders dissected from young, adult and senescent rats.Among a total of 1176 genes present on the arrays, 15 genes showed an increase in expression and 10 genes a decrease with age. Four genes related to nerve growth factor were upregulated whereas NOS type III was downregulated in aging rats.Intrinsic contractility of isolated rat urinary bladders was not changed between adult and aging rats as judged by the response curves to KCl. In contrast, an age‐related increase in the maximal contractile responses to NE, but not PHE, was noticed (13 ± 1, 48 ± 2% and 59 ± 2% at 3, 10 and 30 months, respectively). The α1D‐adrenoceptor antagonist BMY7378 antagonized NE‐induced contractions with low potency in both groups suggesting the involvement of the α1A‐adrenoceptor subtype. This was confirmed by microarray, which demonstrated mRNA expression for the α1A ‐adrenoceptor subtype only.These results suggest that aging of the urinary bladder is associated with an increase in the maximal contractile response to NE which could be due to NO shortage resulting from downregulation of urothelial NOS III.
The preventive effect of captopril or enalapril on reperfusion injury of the kidney of rats is independent of angiotensin II AT1 receptors
Authors: Pazoki‐Toroudi Hamid Reza , Hesami Ali , Vahidi Simin , Sahebjam Farhad , Seifi Behjat , Djahanguiri Bijan 
Published: September 2003

AbstractOcclusion of the artery of organs results in ischaemia. The opening of occluded artery results in tissue lesion identified as reperfusion injury (RI). Renin–angiotensin system seems to be involved in the RI. In this study we assessed the effects of different doses of two inhibitors of angiotensin converting enzyme (captopril or enalapril) and an angiotensin receptor type 1 (AT1) receptor blocker (losartan) in the RI of the kidney of rats. Female rats of 200–250 g were anaesthetized and used for RI studies. Different doses of captopril (5, 20 and 80 mg/kg), enalapril (1, 4 and 16 mg/kg) and/or losartan (5, 10 and 20 mg/kg) were used (s.c.) 120 min prior to the initiation of RI. Kidneys were removed and checked histologically for the presence and the grading of ischaemic injury. Appropriate controls were used as well. RI produced lesions comparable with that of ischaemia. Different doses of captopril or enalapril prevented these lesions. This is suggestive of the involvement of renin–angiotensin system in the RI. Different doses of losartan failed to prevent RI lesions which suggest that the effect of captopril or enalapril are not mediated through the AT1 receptors. Further studies on the involvement of AT2 receptor or other independent mechanisms are suggested.