bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rare actinomycete bacteria from the shallow water sediments of the Trondheim fjord, Norway: isolation, diversity and biological activity
Authors: Bredholdt Harald , Galatenko Olga A. , Engelhardt Kerstin , Fjærvik Espen , Terekhova Larissa P. , Zotchev Sergey B. 
Published: July 2007

SummaryActinomycete bacteria produce a wide variety of secondary metabolites with diverse biological activities, some of which have been developed for human medicine. Rare actinomycetes are promising sources in search for new drugs, and their potential for producing biologically active molecules is poorly studied. In this work, we have investigated the diversity of actinomycetes in the shallow water sediments of the Trondheim fjord (Norway). Due to the use of different selective isolation methods, an unexpected variety of actinomycete genera was isolated. Although the predominant genera were clearly Streptomyces and Micromonospora, representatives of Actinocorallia, Actinomadura, Knoellia, Glycomyces, Nocardia, Nocardiopsis, Nonomuraea, Pseudonocardia, Rhodococcus and Streptosporangium genera were isolated as well. To our knowledge, this is the first report describing isolation of Knoellia and Glycomyces species from the marine environment. 35 selected actinomycete isolates were characterized by 16S rDNA sequencing, and were shown to represent strains from 11 different genera. In addition, these isolates were tested for antimicrobial activity and the presence of polyketide synthase and non‐ribosomal peptide synthetase genes. This study confirms the significant biodiversity of actinobacteria in the Norwegian marine habitats, and their potential for producing biologically active compounds.
Submersed macrophytes play a key role in structuring bacterioplankton community composition in the large, shallow, subtropical Taihu Lake, China
Authors: Wu Qinglong L. , Zwart Gabriel , Wu Jianfeng , Kamst‐van Agterveld Miranda P. , Liu Shuangjiang , Hahn Martin W. 
Published: July 2007

SummaryWithin‐lake horizontal heterogeneity of bacterioplankton community composition (BCC) was investigated in the large and shallow subtropical Taihu Lake (2338 km2, maximum depth < 3 m). Samples were collected at 17 sites along a trophic gradient ranging from mesotrophic to hypertrophic areas in August and September 2004. These sites cover two alternative stable states of shallow lakes, which are basically characterized by the dominance or the lack of submerged macrophytes. In the case of Taihu Lake, the macrophyte‐dominated state is characterized by clear water and immobilized sediment, and the state largely lacking macrophytes is characterized by the dominance of phytoplankton, frequent wind‐driven re‐suspension of sediments, and a high turbidity. Three different methods, i.e. denaturing gradient gel electrophoresis (DGGE), reverse line blot hybridization (RLB) with probes targeting 17 freshwater bacterial groups, and 16S rRNA gene cloning and sequencing, were used for analysis of BCC. The BCC varied strongly between the two alternative ecological states, but less pronounced between phytoplankton‐dominated sites even spanning chlorophyll a gradients from 16.5 (mesotrophic) to 229.8 μg l−1 (hypertrophic). The 16S rRNA gene library representing the turbid water state contained many sequences closely related to sequences previously obtained from soil or freshwater sediment samples. Furthermore, sequences representing two new lineages of freshwater Actinobacteria were obtained from the investigated samples. Comparative statistical analyses of BCC along the investigated ecological gradients revealed that the dominance of submersed macrophytes was the most influential factor on BCC, responsible for a major part of the observed within‐habitat heterogeneity of BCC in Taihu Lake.
Self‐produced extracellular stimuli modulate the Pseudomonas aeruginosa swarming motility behaviour
Authors: Tremblay Julien , Richardson Anne‐Pascale , Lépine François , Déziel Eric 
Published: July 2007

Summary Pseudomonas aeruginosa presents three types of motilities: swimming, twitching and swarming. The latter is characterized by rapid and coordinated group movement over a semisolid surface resulting from morphological differentiation and intercellular interactions. A striking feature of P. aeruginosa swarming motility is the formation of migrating tendrils producing colonies with complex fractal‐like patterns. Previous studies have shown that normal swarming motility is intimately related to the production of extracellular surface‐active molecules: rhamnolipids (RLs), composed of monorhamnolipids (mono‐RLs) and dirhamnolipids (di‐RLs), and 3‐(3‐hydroxyalkanoyloxy) alkanoic acids (HAAs). Here, we report that (i) di‐RLs attract active swarming cells while HAAs behave as strong repellents, (ii) di‐RLs promote and HAAs inhibit tendril formation and migration, (iii) di‐RLs and HAAs display different diffusion kinetics on a surface as di‐RLs spread faster than HAAs in agar, (iv) di‐RLs and HAAs have no effect on swimming cells, suggesting that swarming cells are different from swimming cells not only in morphology but also at the regulatory level and (v) mono‐RLs act as wetting agents. We propose a model explaining how HAAs and di‐RLs together modulate the behaviour of swarming migrating cells by acting as self‐produced negative and positive chemotactic‐like stimuli.
New ways to break an old bond: the bacterial carbon–phosphorus hydrolases and their role in biogeochemical phosphorus cycling
Authors: Quinn John P. , Kulakova Anna N. , Cooley Natalie A. , McGrath John W. 
Published: July 2007

SummaryPhosphonates are organophosphorus molecules that contain the highly stable C–P bond, rather than the more common, and more labile, C–O–P phosphate ester bond. They have ancient origins but their biosynthesis is widespread among more primitive organisms and their importance in the contemporary biosphere is increasingly recognized; for example phosphonate‐P is believed to play a particularly significant role in the productivity of the oceans. The microbial degradation of phosphonates was originally thought to occur only under conditions of phosphate limitation, mediated exclusively by the poorly characterized C–P lyase multienzyme system, under Pho regulon control. However, more recent studies have demonstrated the Pho‐independent mineralization by environmental bacteria of three of the most widely distributed biogenic phosphonates: 2‐aminoethylphosphonic acid (ciliatine), phosphonoacetic acid, and 2‐amino‐3‐phosphonopropionic acid (phosphonoalanine). The three phosphonohydrolases responsible have unique specificities and are members of separate enzyme superfamilies; their expression is regulated by distinct members of the LysR family of bacterial transcriptional regulators, for each of which the phosphonate substrate of the respective degradative operon serves as coinducer. Previously no organophosphorus compound was known to induce the enzymes required for its own degradation. Whole‐genome and metagenome sequence analysis indicates that the genes encoding these newly described C–P hydrolases are distributed widely among prokaryotes. As they are able to function under conditions in which C–P lyases are inactive, the three enzymes may play a hitherto‐unrecognized role in phosphonate breakdown in the environment and hence make a significant contribution to global biogeochemical P‐cycling.
The underside of the cerebral cortex: layer V/VI spiny inverted neurons
Authors: Mendizabal‐Zubiaga Juan L. , Reblet Concepcion , Bueno‐Lopez Jose L. 
Published: July 2007

AbstractThis paper presents an account of past and current research on spiny inverted neurons – alternatively also known as ‘inverted pyramidal neurons’– in rats, rabbits and cats. In our laboratory, we have studied these cells with a battery of techniques suited for light and electron microscopy, including Nissl staining, Golgi impregnation, dye intracellular filling and axon retrograde track‐tracing. Our results show that spiny inverted neurons make up less than 8.5 and 5.5% of all cortical neurons in the primary and secondary rabbit visual cortex, respectively. Infragranular spiny inverted neurons constitute 15 and 8.5% of infragranular neurons in the same animal and areas. Spiny inverted neurons congregate at layers V–VI in all studied species. Studies have also revealed that spiny inverted neurons are excitatory neurons which furnish axons for various cortico‐cortical, cortico‐claustral and cortico‐striatal projections, but not for non‐telencephalic centres such as the lateral and medial geniculate nuclei, the colliculi or the pons. As a group, each subset of inverted cells contributing to a given projection is located below the pyramidal neurons whose axons furnish the same centre. Spiny inverted neurons are particularly conspicuous as a source of the backward cortico‐cortical projection to primary visual cortex and from this to the claustrum. Indeed, they constitute up to 82% of the infragranular cells that furnish these projections. Spiny inverted neurons may be classified into three subtypes according to the point of origin of the axon on the cell: the somatic basal pole which faces the cortical outer surface, the somatic flank and the reverse apical dendrite. As seen with electron microscopy, the axon initial segments of these subtypes are distinct from one another, not only in length and thickness, but also in the number of received synaptic boutons. All of these anatomical features together may support a synaptic‐input integration which is peculiar to spiny inverted neurons. In this way, two differently qualified streams of axonal output may coexist in a projection which arises from a particular infragranular point within a given cortical area; one stream would be furnished by the typical pyramidal neurons, whereas spiny inverted neurons would constitute the other source of distinct information flow.
Autophagic cell death induced by TrkA receptor activation in human glioblastoma cells
Authors: Hansen Katharina , Wagner Bettina , Hamel Wolfgang , Schweizer Michaela , Haag Friedrich , Westphal Manfred , Lamszus Katrin 
Published: July 2007

AbstractThe neurotrophin receptor tropomyosin‐related kinase A (TrkA) and its ligand nerve growth factor (NGF) are expressed in astrocytomas, and an inverse association of TrkA expression with malignancy grade was described. We hypothesized that TrkA expression might confer a growth disadvantage to glioblastoma cells. To analyze TrkA function and signaling, we transfected human TrkA cDNA into the human glioblastoma cell line G55. We obtained three stable clones, all of which responded with striking cytoplasmic vacuolation and subsequent cell death to NGF. Analyzing the mechanism of cell death, we could exclude apoptosis and cellular senescence. Instead, we identified several indications of autophagy: electron microscopy showed typical autophagic vacuoles; acridine orange staining revealed acidic vesicular organelles; acidification of acidic vesicular organelles was prevented using bafilomycin A1; cells displayed arrest in G2/M; increased processing of LC3 occurred; vacuolation was prevented by the autophagy inhibitor 3‐methyladenine; no caspase activation was detected. We further found that both activation of ERK and c‐Jun N‐terminal kinase but not p38 were involved in autophagic vacuolation. To conclude, we identified autophagy as a novel mechanism of NGF‐induced cell death. Our findings suggest that TrkA activation in human glioblastomas might be beneficial therapeutically, especially as several of the currently used chemotherapeutics also induce autophagic cell death.
Lifeguard/neuronal membrane protein 35 regulates Fas ligand‐mediated apoptosis in neurons via microdomain recruitment
Authors: Fernández Miriam , Segura Miguel F. , Solé Carme , Colino Alicia , Comella Joan X. , Ceña Valentín 
Published: July 2007

AbstractFas ligand (FasL)‐receptor system plays an essential role in regulating cell death in the developing nervous system, and it has been implicated in neurodegenerative and inflammatory responses in the CNS. Lifeguard (LFG) is a protein highly expressed in the hippocampus and the cerebellum, and it shows a particularly interesting regulation by being up‐regulated during postnatal development and in the adult. We show that over‐expression of LFG protected cortical neurons from FasL‐induced apoptosis and decreased caspase‐activation. Reduction of endogenous LFG expression by small interfering RNA sensitized cerebellar granular neurons to FasL‐induced cell death and caspase‐8 activation, and also increased sensitivity of cortical neurons. In differentiated cerebellar granular neurons, protection from FasL‐induced cell death could be attributed exclusively to LFG and appears to be independent of FLICE inhibitor protein. Thus, LFG is an endogenous inhibitor of FasL‐mediated neuronal death and it mediates the FasL resistance of CNS differentiated neurons. Finally, we also demonstrate that LFG is detected in lipid rafts microdomains, where it may interact with Fas receptor and regulate FasL‐activated signaling pathways.
Cellular and subcellular rat brain spermidine synthase expression patterns suggest region‐specific roles for polyamines, including cerebellar pre‐synaptic function
Authors: Krauss M. , Weiss T. , Langnaese K. , Richter K. , Kowski A. , Veh R. W. , Laube G. 
Published: July 2007

AbstractIn the brain, the polyamines spermidine (Spd) and spermine (Spm) serve highly specific functions by interacting with various ion channel receptors intimately involved with synaptic signaling. Both, glial cells and neurons contain Spd/Spm, but release and uptake mechanisms could re‐distribute polyamines between cell types. The cellular and subcellular localization of polyamine biosynthetic enzymes may therefore offer a more appropriate tool to identify local sources of enhanced Spd/Spm synthesis, which may be related with specific roles in neuronal circuits and synaptic function. A recently characterized antibody against Spd synthase was therefore used to screen the rat brain for compartment‐specific peaks in enzyme expression. The resulting labeling pattern indicated a clearly heterogeneous expression predominantly localized to neurons and neuropil. The highest levels of Spd synthase expression were detected in the accumbens nucleus, taenia tecta, cerebellar cortex, cerebral cortical layer I, hippocampus, hypothalamus, mesencephalic raphe nuclei, central and lateral amygdala, and the circumventricular organs. Besides a diffuse labeling of the neuropil in several brain areas, the distinct labeling of mossy fiber terminals in the cerebellar cortex directly indicated a synaptic role for Spd synthesis. Electron microscopy revealed a preferential distribution of the immunosignal in synaptic vesicle containing areas. A pre‐synaptic localization was also observed in parallel and climbing fiber terminals. Electrophysiological recordings in acute cerebellar slices revealed a Spd‐induced block of evoked extracellular field potentials resulting from mossy fiber stimulation in a dose‐dependent manner.
ATP‐sensitive potassium channel opener iptakalim protects against MPP+‐induced astrocytic apoptosis via mitochondria and mitogen‐activated protein kinase signal pathways
Authors: Zhang Shu , Zhou Fang , Ding Jian‐Hua , Zhou Xi‐Qiao , Sun Xiu‐Lan , Hu Gang 
Published: July 2007

AbstractInhibition of astrocytic apoptosis has been regarded as a novel prospective strategy for treating neurodegenerative disorders such as Parkinson’s disease. In the present study, we demonstrated that iptakalim (IPT), an ATP‐sensitive potassium channel (KATP channel) opener, exerted protective effect on MPP+‐induced astrocytic apoptosis, which was reversed by selective mitochondrial KATP channel blocker 5‐hydroxydecanoate. Further study revealed that IPT inhibited glutathione (GSH) depletion, mitochondrial membrane potential loss and subsequent release of pro‐apoptotic factors (cytochrome c and apoptosis‐inducing factor (AIF), and c‐Jun NH2‐terminal kinase/mitogen‐activated protein kinases (MAPK) phosphorylation induced by MPP+. Meanwhile, extracellular signal‐regulated kinase (ERK) 1/2 inhibitor PD98059 inhibited the protective effect of IPT on MPP+‐induced astrocytic apoptosis. Furthermore, IPT could also activate ERK/MAPK and maintain increased phospho‐ERK1/2 level after MPP+ exposure. Taken together, these findings reveal for the first time that IPT protects against MPP+‐induced astrocytic apoptosis via inhibition of mitochondria apoptotic pathway and regulating the MAPK signal transduction pathways by opening mitochondrial ATP‐sensitive potassium (mitoKATP) channels in astrocytes. And targeting KATP channels expressed in astrocytes may provide a novel therapeutic strategy for neurodegenerative disorders.
Liposomes of phosphatidylcholine: a biological natural surfactant as a dispersing agent
Authors: Martí M , Coderch L , De La Maza A , Parra J L 
Published: July 2007

Disperse dyes are very hydrophobic molecules that in their commercial form are usually milled in the presence of large amounts of dispersing agents (synthetic surfactants). Other dispersing agents are added as auxiliaries during the dyeing process. These synthetic surfactants were substituted for liposomes prepared with phosphatidylcholine, a well‐known biological surfactant of natural origin which is environmentally friendly, and liposomes were studied as a dispersing agent in polyester dyeing.The physicochemical behaviour of dye dispersion was analysed by two experimental measurements: the aggregation process of dye particles by filtration of dispersion and the determination of the turbidity ratio. The results obtained show the usefulness of liposomes as a dispersing auxiliary in a dyeing process, avoiding aggregation of dye molecules at high temperatures. Moreover, polyester dyeing shows similar final exhaustions, approximately 90%, at different kinetics, when liposomes are used.
Concentrated Heparin Lock Is Associated with Major Bleeding Complications after Tunneled Hemodialysis Catheter Placement
Authors: Yevzlin Alexander S. , Sanchez Robert J. , Hiatt Jeanne G. , Washington Marilyn H. , Wakeen Maureen , Hofmann R. Michael , Becker Yolanda T. 
Published: July 2007

AbstractVascular access complications, including thrombosis, are associated with significant patient morbidity and mortality. Currently, up to 60% of new patients and 30% of prevalent patients are using a catheter for dialysis. To prevent interdialytic catheter thrombosis, these devices are routinely locked with concentrated heparin solutions. Several recent studies have elucidated the potential for abnormal coagulation markers (aPTT) that may arise from this practice. This abnormal elevation in aPTT may be explained by significant early and late leakage from the catheter that occurs after performing a catheter lock. To date no study has evaluated the impact of this practice, or the elevation in aPTT that may result from it, on bleeding complication rates. We conducted a retrospective analysis comparing bleeding rates in subjects who received concentrated heparin catheter lock (5000 u/cc) [group 1, n = 52] to those who received citrate or dilute heparin catheter lock (1000 u/cc) [group 2, n = 91] immediately after tunneled hemodialysis catheter insertion. Baseline characteristics did not differ between the groups except for the preprocedure INR, which was higher in the postpolicy group compared with the prepolicy group (1.29 vs. 1.21, p = 0.04). Results from logistic regression analyses revealed that the likelihood of a composite bleeding event in group 1 was 11.9 times that of a composite bleeding event in group 2, p = 0.04. Concentrated heparin (5000 u/ml) is associated with increased major bleeding complications posttunneled catheter placement compared with low‐dose heparin (1000 u/ml) or citrate catheter lock solution, p = 0.02. Given the findings of this study, a randomized controlled trial comparing the safety and efficacy of common anticoagulation lock solutions is warranted.
Percutaneous Renal Biopsy: Comparison of Blind and Real‐Time Ultrasound‐Guided Technique
Authors: Maya Ivan D. , Maddela Prathyusha , Barker Jill , Allon Michael 
Published: July 2007

AbstractThe use of real‐time ultrasound‐guided renal biopsy is believed to be superior to blind biopsy, but there are few reports comparing the two techniques. The goal of the present study was to compare the outcomes of ultrasound‐guided and blind renal biopsies at a single teaching institution, in terms of adequacy of tissue yield and frequency of hemorrhagic complications. We reviewed retrospectively the outcomes of all patients undergoing a percutaneous native kidney biopsy during a 2‐year period (January 1, 2004 to December 31, 2005). Of 129 renal biopsies, 65 were ultrasound‐guided and 64 were performed by the blind technique. All biopsies were performed by nephrology fellows under direct faculty supervision. The two patient groups were comparable in terms of age, sex, race, diabetes, hypertension, serum creatinine, and hematocrit. The mean number of glomeruli per biopsy was higher in the ultrasound‐guided group than in the patients with a blind biopsy (18 ± 9 versus 11 ± 9, p = 0.0001). An inadequate tissue sample requiring repeat biopsy occurred in 0% of the ultrasound‐guided biopsies and 16% of the blind biopsies (p = 0.0006). Large hematomas requiring vascular intervention or transfusion were less frequent in the ultrasound‐guided biopsies (0% versus 11%, p = 0.006). The hematocrit 24 hours postbiopsy was higher in the ultrasound‐guided biopsies when compared with the blind biopsies (32 ± 5% versus 30 ± 4%, p = 0.04). When compared with blind renal biopsy, real‐time ultrasound‐guided percutaneous renal biopsy provides a superior yield of kidney tissue and results in fewer hemorrhagic complications. Real‐time ultrasound‐guided renal biopsy is the preferred technique.
An Alternative Approach to a Totally Occluded Subclavian Vein in a Malfunctioning Arteriovenous Fistula
Authors: Packer Jeffrey 
Published: July 2007

AbstractEndovascular therapy is useful in the treatment of a malfunctioning or nonmaturing arteriovenous (AV) fistula. When a standard trans‐access approach fails, alternative approaches can be attempted. A patient with a malfunctioning fistula is presented describing the use of a successful transjugular approach after an unsuccessful trans‐fistula attempt. The merits of this alternative method are discussed. An alternative means of treating a malfunctioning dialysis AV fistula may help increase the prevalence of AV fistulae in the hemodialysis population.
PHOSPHORUS METABOLISM AND MANAGEMENT IN CHRONIC KIDNEY DISEASE: Renal Osteodystrophy, Phosphate Homeostasis, and Vascular Calcification
Authors: Hruska Keith A. , Saab Georges , Mathew Suresh , Lund Richard 
Published: July 2007

AbstractNew advances in the pathogenesis of renal osteodystrophy (ROD) change the perspective from which many of its features and treatment are viewed. Calcium, phosphate, parathyroid hormone (PTH), and vitamin D have been shown to be important determinants of survival associated with kidney diseases. Now ROD dependent and independent of these factors is linked to survival more than just skeletal frailty. This review focuses on recent discoveries that renal injury impairs skeletal anabolism decreasing the osteoblast compartment of the skeleton and consequent bone formation. This discovery and the discovery that PTH regulates the hematopoietic stem cell niche alters our view of secondary hyperparathyroidism in chronic kidney disease (CKD) from that of a disease to that of a necessary adaptation to renal injury that goes awry. Furthermore, ROD is shown to be an underappreciated factor in the level of the serum phosphorus in CKD. The discovery and the elucidation of the mechanism of hyperphosphatemia as a cardiovascular risk in CKD change the view of ROD. It is now recognized as more than a skeletal disorder, it is an important component of the mortality of CKD that can be treated.