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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Many models of Parkinson's disease (PD) have succeeded in replicating dopaminergic neuron loss or α-synuclein aggregation but not the formation of classical Lewy bodies, the pathological hallmark of PD. Our cybrid model of sporadic PD was created by introducing the mitochondrial genes from PD patients into neuroblastoma cells that lack mitochondrial DNA. Previous studies using cybrids have shown that information encoded by mitochondrial DNA in patients contributes to many pathogenic features of sporadic PD. In this paper, we report the generation of fibrillar and vesicular inclusions in a long-term cybrid cell culture model that replicates the essential antigenic and structural features of Lewy bodies in PD brain without the need for exogenous protein expression or inhibition of mitochondrial or proteasomal function. The inclusions generated by PD cybrid cells stained with eosin, thioflavin S, and antibodies to α-synuclein, ubiquitin, parkin, synphilin-1, neurofilament, β-tubulin, the proteasome, nitrotyrosine, and cytochrome c. Future studies of these cybrids will enable us to better understand how Lewy bodies form and what role they play in the pathogenesis of PD.
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Sporadic Parkinson's disease is associated with a defect in the activity of complex I of the mitochondrial electron transport chain. This electron transport chain defect is transmitted through mitochondrial DNA, and when expressed in host cells leads to increased oxygen free radical production, increased antioxidant enzyme activities, and increased susceptibility to programmed cell death. Pramipexole, a chemically novel dopamine agonist used for the treatment of Parkinson's disease symptoms, possesses antioxidant activity and is neuroprotective toward substantia nigral dopamine neurons in hypoxic-ischemic and methamphetamine models. We found that pramipexole reduced the levels of oxygen radicals produced by methylpyridinium ion (MPP+) both when incubated with SH-SY5Y cells and when perfused into rat striatum. Pramipexole also exhibited a concentration-dependent inhibition of opening of the mitochondrial transition pore induced by calcium and phosphate or MPP+. These results suggest that pramipexole may be neuroprotective in Parkinson's disease by attenuating intracellular processes such as oxygen radical generation and the mitochondrial transition pore opening, which are associated with programmed cell death.
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: In vitro studies indicate that p42/p44MAPK phosphorylate both nuclear and cytoplasmic proteins. However, the functional targets of p42/p44MAPK activation in vivo remain unclear. To address this question, we localized activated p42/p44MAPK in hippocampus and cortex and determined their signaling effects after electroconvulsive shock treatment (ECT) in rats. Phosphorylated p42/p44MAPK content increased in the cytoplasm of hippocampal neurons in response to ECT. Consistent with this cytoplasmic localization, inhibition of ECT-induced p42/p44MAPK activation by the extracellular signal-regulated kinase kinase inhibitor PD098059 blocked phosphorylation of the cytoplasmic protein microtubule-associated protein 2c (MAP2c), but failed to inhibit the induction of the nuclear protein c-Fos in response to ECT. In contrast to hippocampal neurons, cortical neurons exhibited an increase in amount of phosphorylated p42/p44MAPK in both the nucleus and cytoplasm after ECT. Accordingly, PD098059 blocked the induction of Fos-like immunoreactivity in the nuclei of cortical neurons as well as MAP2c phosphorylation in the cytoplasm. Our data indicate that both nuclear and cytoplasmic substrates can be activated by p42/p44MAPK in vivo. However, the functional targets of p42/p44MAPK signaling depend on the precise location of p42/p44MAPK within different subcellular compartments of brain regions. These results indicate unique functional pathways of p42/p44MAPK-mediated signal transduction within different brain regions in vivo.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Ecology of freshwater fish 12 (2003), S. 0 
    ISSN: 1600-0633
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  – We studied diel microhabitat use at the focal point of age-0 bull trout, Salvelinus confluentus, in Indian Creek, Washington during mid-summer and fall of 1997. Microhabitat variables included water depth and velocity, distance from the stream bottom, habitat and refuge use, substrate type, and substrate embeddedness. Age-0 fish were located over fines and gravel substrates in shallow, low-velocity water near stream margins, but were located in shallower water at night. Bull trout were highly associated with loose substrate, and used the substrate interstices for refuge cover. Diurnal bull trout counts decreased and no age-0 fish were observed after 15 September at water temperatures below 6.1 °C. Nocturnal counts remained relatively constant throughout the study. Our results suggest that age-0 bull trout surveys be conducted at night when summer water temperatures begin to decline.
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  • 5
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Enteroaggregative Escherichia coli (EAEC) forms thick biofilms on the intestinal mucosa. Here, we show that most EAEC strains form a biofilm on glass or plastic surfaces when grown in cell culture medium with high sugar and osmolarity. Biofilm-forming ability in two prototype EAEC strains required aggregative adherence fimbriae (AAF), although many other EAEC strains that do not express AAF also developed biofilms under these conditions. Ten thousand transposon mutants of EAEC strain 042 were isolated, and 100 were found to be deficient in biofilm formation. Of these, 93 were either deficient in in vitro growth or mapped to genes known to be required for AAF/II expression. Of the seven remaining insertions, five mapped to one of two unsuspected loci. Two insertions involved the E. coli chromosomal fis gene, a DNA-binding protein that is involved in growth phase-dependent regulation. Using reverse transcription–polymerase chain reaction (RT–PCR), we determined that the effect of fis was at the level of transcription of the AAF/II activator aggR. Biofilm formation also required the product of the yafK gene, which is predicted to encode a secreted 28 kDa protein. The yafK product is required for transcription of AAF/II-encoding genes. Our data do not suggest a role for type 1 fimbriae or motility in biofilm formation. EAEC appears to form a novel biofilm, which may be mediated solely by AAF and may reflect its interactions with the intestinal mucosa.
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  • 6
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The fim switch of Escherichia coli is responsible for phase-variable expression of type 1 fimbriae. Switching in the ON-to-OFF and OFF-to-ON directions is promoted by the FimB recombinase, while the FimE recombinase directs switching predominantly in the ON-to-OFF direction. The effects of local promoter activity and the H-NS nucleoid-associated protein on inversion of the switch were assessed. In contrast to FimB-mediated inversion, inversion of the switch by the FimE recombinase was unaffected by the H-NS status of the cell. Transcription towards the switch from within a translationally inactivated fimE gene was found to bias the switch strongly in the OFF direction, creating a FimE+-like phenotype in the absence of the FimE protein. This biasing was H-NS dependent and was also contingent on transcription from within the switch. These data show that local transcription and a nucleoid-associated protein both contribute to the modulation of a site-specific recombination event on the bacterial chromosome.
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  • 7
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Urinary tract infection (UTI) is a very common extraintestinal infection, and Escherichia coli is by far the most common causative organism. Uropathogenic E. coli possess traits that distinguish them from commensal strains of E. coli, such as secretion systems that allow virulence factors to be targeted to extracytoplasmic compartments. One of at least five characterized secretion mechanisms is the autotransporter system, which involves translocation of a protein across the inner membrane, presumably via the sec system, and across the outer membrane through a β-barrel porin structure formed by the carboxy-terminus autotransporter domain. We identified a 107 kDa protein that was expressed significantly more often by E. coli strains associated with the clinical syndrome of acute pyelonephritis than by faecal strains (P = 0.029). We isolated the protein from E. coli CFT073, a strain cultured from the blood and urine of a patient with acute pyelonephritis. The N-terminal amino acid sequence showed highest similarity to two known SPATE (serine protease autotransporters of Enterobacteriaceae) proteins, Pet and EspC. Using a 509 bp probe from the 5′ region of pet, 10 cosmid clones of an E. coli CFT073 gene library were positive for hybridization. From one cosmid clone, a 7.5 kb EcoRI restriction fragment, which reacted strongly with the probe, was shown to include the entire 3885 bp gene. The predicted 142 kDa protein product possesses the three domains that are typical of SPATE autotransporters: an unusually long signal sequence of 49 amino acids; a 107 kDa passenger domain containing a consensus serine protease active site (GDSGSG); and a C-terminal autotransporter domain of 30 kDa. The protein exhibited serine protease activity and displayed cytopathic activity on VERO primary kidney, HK-2 bladder and HEp-2 cell lines; the name Sat (secreted autotransporter toxin) was derived from these properties. In addition, Sat antibodies were present in the serum of mice infected with E. coli CFT073. Based upon its association with pathogenic isolates, its cytopathic phenotype and its ability to elicit a strong antibody response after infection, we postulate that Sat represents a novel virulence determinant of uropathogenic E. coli.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 33 (1999), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The expression of most bacterial genes is controlled at the level of transcription via promoter control mechanisms that permit a graded response. However, an increasing number of bacterial genes are found to exhibit an ‘all-or-none’ control mechanism that adapts the bacterium to more than one environment. One such mechanism is phase variation, traditionally defined as the high-frequency ON↔OFF switching of phenotype expression. Phase variation events are usually random, but may be modulated by environmental conditions. The mechanisms of phase variation events and their significance within the microbial community are discussed here.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 33 (1999), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
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  • 10
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective  To evaluate the efficacy of metronidazole to reduce post-abortion complications among women with bacterial vaginosis.Design  A randomised, double-blind placebo-controlled trial.Setting  An American outpatient abortion facility between April 1999 and June 2000.Sample  Women presenting for surgical abortion were screened for bacterial vaginosis using a pH and amines card test.Methods  Women positive for elevated pH and amines on a self-collected vaginal discharge sample were randomised to 1000 mg oral metronidazole before abortion followed by 500 mg twice daily or placebo. All randomised women were also dispensed 100 mg doxycycline to take twice daily for seven days.Main outcome measures  Data were collected by phone, daily diary or visit and scored from 0 to 7 for post-abortion complications. Intention-to-treat analyses were completed prior to unblinding.Results  Of 1764 women screened by card test, 638 (36%) were positive. Of these, 393 were randomised. Follow up data were available for 253 (64%) of these women. A complication score of 3 or more occurred in 21% of women assigned to metronidazole, compared with 19% in those assigned placebo (RR 1.1, 95% CI 0.7–1.9). Among 153 women with Gram stain confirmation for bacterial vaginosis, there was a similar lack of benefit with treatment (RR 1.6, 95% CI 0.9–3.0). No individual symptom or sign was statistically different between groups even for second trimester procedures.Conclusion  Among women undergoing abortion and diagnosed with bacterial vaginosis, oral metronidazole, in conjunction with doxycycline, did not reduce post-abortion complications.
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