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81.
82.
Methods used to date for the isolation of DNA from polyacrylamide gels are elution based, time-consuming and with low yield in DNA. This paper describes an improved system employing polyacrylamide gels made of a meltable matrix. The new system was successfully applied to in situ DNA footprinting following gel retardation assays. 相似文献
83.
Diederik WJ Dippel Eric J van Breda H Bart van der Worp H Maarten A van Gemert Ron J Meijer L Jaap Kappelle Peter J Koudstaal 《BMC cardiovascular disorders》2003,3(1):1-8
Background
Body temperature is a strong predictor of outcome in acute stroke. In a previous randomized trial we observed that treatment with high-dose acetaminophen (paracetamol) led to a reduction of body temperature in patients with acute ischemic stroke, even when they had no fever. The purpose of the present trial was to study whether this effect of acetaminophen could be reproduced, and whether ibuprofen would have a similar, or even stronger effect.Methods
Seventy-five patients with acute ischemic stroke confined to the anterior circulation were randomized to treatment with either 1000 mg acetaminophen, 400 mg ibuprofen, or placebo, given 6 times daily during 5 days. Treatment was started within 24 hours from the onset of symptoms. Body temperatures were measured at 2-hour intervals during the first 24 hours, and at 6-hour intervals thereafter.Results
No difference in body temperature at 24 hours was observed between the three treatment groups. However, treatment with high-dose acetaminophen resulted in a 0.3°C larger reduction in body temperature from baseline than placebo treatment (95% CI: 0.0 to 0.6 °C). Acetaminophen had no significant effect on body temperature during the subsequent four days compared to placebo, and ibuprofen had no statistically significant effect on body temperature during the entire study period.Conclusions
Treatment with a daily dose of 6000 mg acetaminophen results in a small, but potentially worthwhile decrease in body temperature after acute ischemic stroke, even in normothermic and subfebrile patients. Further large randomized clinical trials are needed to study whether early reduction of body temperature leads to improved outcome. 相似文献84.
HS5 of the human beta-globin locus control region: a developmental stage-specific border in erythroid cells 下载免费PDF全文
Wai AW Gillemans N Raguz-Bolognesi S Pruzina S Zafarana G Meijer D Philipsen S Grosveld F 《The EMBO journal》2003,22(17):4489-4500
Elements with insulator/border activity have been characterized most extensively in Drosophila melanogaster. In vertebrates, the first example of such an element was provided by a hypersensitive site of the chicken beta-globin locus, cHS4. It has been proposed that the homologous site in humans, HS5, functions as a border of the human beta-globin locus. Here, we have characterized HS5 of the human beta-globin locus control region. We have examined its tissue-specificity and assessed its insulating properties in transgenic mice using a lacZ reporter assay. Most importantly, we have tested its enhancer blocking activity in the context of the full beta-globin locus. Our results show that HS5 is erythroid-specific rather than ubiquitous in human tissues. Furthermore, HS5 does not fulfil the criteria of a general in vivo insulator in the transgene protection assay. Finally, a HS5 conditional deletion from the complete locus demonstrates that HS5 has no discernable activity in adult erythroid cells. Surprisingly, HS5 functions as an enhancer blocker in embryonic erythroid cells. We conclude that HS5 is a developmental stage-specific border in erythroid cells. 相似文献
85.
Oprins JC van der Burg C Meijer HP Munnik T Groot JA 《American journal of physiology. Cell physiology》2001,280(4):C789-C795
In a previous study, it was found thatexposure to tumor necrosis factor- (TNF-) potentiated theelectrophysiological response to carbachol in a time-dependent andcycloheximide-sensitive manner. It was deduced that the potentiationcould be due to protein kinase C activity because of increased1,2-diacylglycerol. It was also observed that propranolol coulddecrease the electrophysiological response to carbachol (Oprins JC,Meijer HP, and Groot JA. Am J Physiol Cell Physiol 278:C463-C472, 2000). The aim of the present study was to investigatewhether the phospholipase D (PLD) pathway plays a role in the carbacholresponse and the potentiating effect of TNF-. Thetransphosphatidylation reaction in the presence of the primary alcohol1-butanol [leading to stable phosphatidylbutanol (Pbut) formation]was used to measure activity of PLD. The phosphatidic acid (PA) levelswere also measured. Muscarinic stimulation resulted in an increasedformation of Pbut and PA. TNF- decreased levels of PA. 相似文献
86.
Verburg M Renes IB Meijer HP Taminiau JA Büller HA Einerhand AW Dekker J 《American journal of physiology. Gastrointestinal and liver physiology》2000,279(5):G1037-G1047
Proliferation, differentiation, and cell death were studied in small intestinal and colonic epithelia of rats after treatment with methotrexate. Days 1-2 after treatment were characterized by decreased proliferation, increased apoptosis, and decreased numbers and depths of small intestinal crypts in a proximal-to-distal decreasing gradient along the small intestine. The remaining crypt epithelium appeared flattened, except for Paneth cells, in which lysozyme protein and mRNA expression was increased. Regeneration through increased proliferation during days 3-4 coincided with villus atrophy, showing decreased numbers of villus enterocytes and decreased expression of the enterocyte-specific genes sucrase-isomaltase and carbamoyl phosphate synthase I. Remarkably, goblet cells were spared at villus tips and remained functional, displaying Muc2 and trefoil factor 3 expression. On days 8-10, all parameters had returned to normal in the whole small intestine. No methotrexate-induced changes were seen in epithelial morphology, proliferation, apoptosis, Muc2, and TFF3 immunostaining in the colon. The observed small intestinal sparing of Paneth cells and goblet cells following exposure to methotrexate is likely to contribute to epithelial defense during increased vulnerability of the intestinal epithelium. 相似文献
87.
Dynamic relocalization of phage phi 29 DNA during replication and the role of the viral protein p16.7 下载免费PDF全文
We have examined the localization of DNA replication of the Bacillus subtilis phage phi 29 by immunofluorescence. To determine where phage replication was localized within infected cells, we examined the distribution of phage replication proteins and the sites of incorporation of nucleotide analogues into phage DNA. On initiation of replication, the phage DNA localized to a single focus within the cell, nearly always towards one end of the host cell nucleoid. At later stages of the infection cycle, phage replication was found to have redistributed to multiple sites around the periphery of the nucleoid, just under the cell membrane. Towards the end of the cycle, phage DNA was once again redistributed to become located within the bulk of the nucleoid. Efficient redistribution of replicating phage DNA from the initial replication site to various sites surrounding the nucleoid was found to be dependent on the phage protein p16.7. 相似文献
88.
The Pf3 major coat protein of the Pf3 bacteriophage is stored in the inner membrane of the infected cell during the reproductive cycle. The protein consists of 44 amino acids, and contains an acidic amphipathic N-terminal domain, a hydrophobic domain, and a short basic C-terminal domain. The mainly alpha-helical membrane-bound protein traverses the membrane once, leaving the C-terminus in the cytoplasm and the N-terminus in the periplasm. A cysteine-scanning approach was followed to measure which part of the membrane-bound Pf3 protein is inside or outside the membrane. In this approach, the fluorescence probe N-[(iodoacetyl)amino]ethyl-1-sulfonaphthylamine (IAEDANS) was attached to single-cysteine mutants of the Pf3 coat protein. The labeled mutant coat proteins were reconstituted into the phospholipid DOPC/DOPG (80/20 molar ratio) and DOPE/DOPG (80/20 molar ratio) model membranes. We subsequently studied the fluorescence characteristics at the different positions in the protein. We measured the local polarity of the environment of the probe, as well as the accessibility of the probe to the fluorescence quencher acrylamide. The results of this study show a single membrane-spanning protein with both the C- and N-termini remaining close to the surface of the membrane. A nearly identical result was seen previously for the membrane-bound M13 coat protein. On the basis of a comparison between the results from both studies, we suggest an "L-shaped" membrane-bound model for the Pf3 coat protein. DOPE-containing model membranes revealed a higher polarity, and quenching efficiency at the membrane/water interface. Furthermore, from the outside to the inside of the membrane, a steeper polarity gradient was measured at the PE/PG interface as compared to the PC/PG interface. These results suggest a thinner interface for DOPE/DOPG than for DOPC/DOPG membranes. 相似文献
89.
Duckworth AW Grant WD Jones BE Meijer D Márquez MC Ventosa A 《Extremophiles : life under extreme conditions》2000,4(1):53-60
A number of novel alkaliphilic organotrophic bacteria have been isolated from several saline and alkaline East African soda
lakes. The new isolates grow at pH values between 7.0 and 11.0, with pH optima for growth between 9.0 and 10.0. Growth occurs
at total salts concentration between 0% and 20% (w/v) with optimum at 0%–7% (w/v). Phylogenetic analyses based on 16S rDNA
sequence comparison indicate that these isolates are related (>96% similarity) to members of the Halomonadaceae within the γ-3 subdivision of the Proteobacteria. These analyses indicate that existing species within the Halomonadaceae fell within three main groups, one group comprising the type species of Halomonas, Halomonas elongata, and a number of other known species including one soda lake isolate. A second group constituting most of the remaining known
species of Halomonas and related Chromohalobacter spp. includes 3 soda lake isolates with high DNA–DNA homologies. The third group included Halomonas halodenitrificans, Halomonas desiderata, Halomonas cupida, and 13 soda lake isolates. Phenotypic comparisons indicated that the majority of soda lake strains shared similar morphological,
phenotypic, and chemotaxonomic properties to known strains of Halomonas but grew under alkaline conditions. The 3 soda lake isolates with high DNA–DNA homologies were, however, significantly different
in antibiotic sensitivity pattern and in the utilization of several substrates, were unable to reduce nitrite, and showed
low DNA–DNA homologies with known halomonads in the same group. We propose that these isolates comprise a new species of the
genus Halomonas that we name Halomonas magadii sp. nov. The type strain is strain 21 MI (NCIMB 13595).
Received: July 20, 1999 / Accepted: October 29, 1999 相似文献
90.
In recent years, it has been recognised that improvements to classic models of muscle mechanical behaviour are often necessary
for properly modelling co-ordinated multi-joint actions. In this respect, the purpose of the present study was to improve
on modelling stretch-induced force enhancement and shortening-induced force depression of muscle contraction. For this purpose,
two models were used: a modified Hill model and a model based loosely on mechano-chemistry of the cross-bridge cycle (exponential
decay model). The models were compared with a classic Hill model and experimental data. Parameter values were based, as much
as possible, on experimental findings in the literature, and tested with new experiments on the gastrocnemius of the rat.
Both models describe many features of slow-ramp movements well during short contractions (300–500 ms), but long-duration behaviour
is described only partly. The exponential decay model does not incorporate a force–velocity curve. Therefore, its good performance
indicates that the status of the classic force–velocity characteristic may have to be reconsidered. Like movement-induced
force depression and enhancement, it seems a particular manifestation of time-dependent force behaviour of muscle, rather
than a fundamental property of muscle (like the length–tension curve). It is argued that a combination of the exponential
decay model (or other models based on the mechano-chemistry of contraction) and structurally based models may be fruitful
in explaining this time-dependent contraction behaviour. Furthermore, not in the least because of its relative simplicity,
the exponential decay model may prove more suitable for modelling multi-joint movements than the Hill model.
Received: 19 March 1999 / Accepted in revised form: 9 June 2000 相似文献