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101.
René W.M. van der Hulst Josbert J. Keller Erik A.J. Rauws Guido N.J. Tytgat 《Helicobacter》1996,1(1):6-19
Background. None of the currently used anti- Helicobacter pylori drug regimens cures the infection 100%, and cure results still vary considerably. The present article reviews the effectiveness of currently used antimicrobial regimens, aimed to cure H. pylori infection.
Methods. Data collection started from the beginning of the anti- H. pylori -therapy era until May 1995. No attempt at formal metanalysis has been made, because many studies have been published only in abstract form. Attempts were made to exclude duplicates of studies by comparison to previously reported ones; the authors of suspected duplicates were contacted. After amalgamation of the number of included patients and the number of successfully treated patients, the mean values of eradication rates and the 95% confidence intervals were calculated.
Results. A total of 237 treatment arms were analyzed. Bismuth triple therapy continues to reach high eradication rates worldwide (78–89%). Side effects leading to diminished patient compliance and the marked decline of eradication efficacy in cases of metronidazole resistance are considered to be the major drawbacks of this therapy. Proton pump inhibitor (PPI) dual therapy is better tolerated with fewer side effects than is bismuth triple therapy. The mean eradication rates vary from 55 to 75%, and the extremes lie between 24 and 93%. PPI triple therapies have been shown to be very effective against H. pylori (eradication rates, 80–89%). Quadruple therapy leads to a mean eradication rate of 96%.
Conclusion. Based on efficacy, PPI triple or bismuth triple therapy are recommended as first-line treatment for H. pylori infection. Quadruple therapy could serve as second-line treatment for eradication of initial failures and in case of metronidazole resistance. 相似文献
Methods. Data collection started from the beginning of the anti- H. pylori -therapy era until May 1995. No attempt at formal metanalysis has been made, because many studies have been published only in abstract form. Attempts were made to exclude duplicates of studies by comparison to previously reported ones; the authors of suspected duplicates were contacted. After amalgamation of the number of included patients and the number of successfully treated patients, the mean values of eradication rates and the 95% confidence intervals were calculated.
Results. A total of 237 treatment arms were analyzed. Bismuth triple therapy continues to reach high eradication rates worldwide (78–89%). Side effects leading to diminished patient compliance and the marked decline of eradication efficacy in cases of metronidazole resistance are considered to be the major drawbacks of this therapy. Proton pump inhibitor (PPI) dual therapy is better tolerated with fewer side effects than is bismuth triple therapy. The mean eradication rates vary from 55 to 75%, and the extremes lie between 24 and 93%. PPI triple therapies have been shown to be very effective against H. pylori (eradication rates, 80–89%). Quadruple therapy leads to a mean eradication rate of 96%.
Conclusion. Based on efficacy, PPI triple or bismuth triple therapy are recommended as first-line treatment for H. pylori infection. Quadruple therapy could serve as second-line treatment for eradication of initial failures and in case of metronidazole resistance. 相似文献
102.
Effects of large Saduria entomon (Isopoda) on spatial distribution of their small S. entomon and Monoporeia affinis (Amphipoda) prey 总被引:3,自引:0,他引:3
We performed laboratory experiments to investigate the effects of predator avoidance and numerical effects of predation on spatial distribution of small Saduria entomon (Isopoda) and Monoporeia affinis (Amphipoda), with large S. entomon as predators. The horizontal distribution and mortality of the prey species, separately and together, were studied in aquaria with a spatial horizontal refuge. We also estimated effects of refuge on mortality of small S. entomon and M. affinis by experiments without the refuge net. In addition, we investigated whether predation risk from large S. entomon influenced the swimming activity of M. affinis, to clarify the mechanisms behind the spatial distribution. Both small S. entomon and M. affinis avoided large S. entomon. The avoidance behaviour of M. fffinis contributed about 10 times more to the high proportion in the refuge than numerical effects of predation. Due to the low mortality of small S. entomon the avoidance behaviour of this species was even more important for the spatial distribution. The combined effect of avoidance behaviour and predation in both species was aggregation, producting a positive correlation between the species in density. M. affinis showed two types of avoidance behaviour. In the activity experiments they reduced activity by 36% and buried themselves in the sediment. In the refuge experiments we also observed avoidance behaviour with the emigration rate from the predator compartment being twice the immigration rate. The refuge did not lower predation mortality in M. affinis, probably due to the small scale of the experimental units in relation to the mobility of the species. Predation mortality in small S. entomon was higher in absence of a refuge and especially high in absence of M. affinis. 相似文献
103.
Altered Growth and Wood Characteristics in Transgenic Hybrid Aspen Expressing Agrobacterium tumefaciens T-DNA Indoleacetic Acid-Biosynthetic Genes 总被引:3,自引:0,他引:3
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Tuominen H Sitbon F Jacobsson C Sandberg G Olsson O Sundberg B 《Plant physiology》1995,109(4):1179-1189
A key regulator of cambial growth is the plant hormone indoleacetic acid (IAA). Here we report on altered wood characteristics and growth patterns in transgenic hybrid aspen (Populus tremula L. x Populus tremuloides Michx.) expressing Agrobacterium tumefaciens T-DNA IAA-biosynthetic iaaM and iaaH genes. Eighteen lines simultaneously expressing both genes were regenerated. Of these, four lines, verified to be transgenic by northern blot analysis, were selected and raised under controlled growth conditions. All four lines were affected in their growth patterns, including alterations in height and stem diameter growth, internode elongation, leaf enlargement, and degree of apical dominance. Two transgenic lines, showing the most distinct phenotypic deviation from the wild type, were characterized in more detail for free and conjugated IAA levels and for wood characteristics. Both lines showed an altered IAA balance, particularly in mature leaves and roots where IAA levels were elevated. They also exhibited changes in wood anatomy, most notably a reduction in vessel size, an increase in vessel density, and changes in ray development. Thus, the recent development of techniques for gene transfer to forest trees enabled us to investigate the influence of an altered IAA balance on xylem development in an intact experimental system. In addition, the results demonstrate the possibility of manipulating wood properties in a forest tree through controlled changes of IAA concentration and distribution. 相似文献
104.
Joanna K. Bowen Matthew D. Templeton Keith R. Sharrock Ross N. Crowhurst Erik H. A. Rikkerink 《Molecular & general genetics : MGG》1995,246(2):196-205
The feasibility of performing routine transformation-mediated mutagenesis in Glomerella cingulata was analysed by adopting three one-step gene disruption strategies targeted at the pectin lyase gene pnIA. The efficiencies of disruption following transformation with gene replacement- or gene truncation-disruption vectors were compared. To effect replacement-disruption, G. cingulata was transformed with a vector carrying DNA from the pnlA locus in which the majority of the coding sequence had been replaced by the gene for hygromycin B resistance. Two of the five transformants investigated contained an inactivated pnlA gene (pnlA
–
);both also contained ectopically integrated vector sequences. The efficacy of gene disruption by transformation with two gene truncation-disruption vectors was also assessed. Both vectors carried a 5and 3truncated copy of the pnlA coding sequence, adjacent to the gene for hygromycin B resistance. The promoter sequences controlling the selectable marker differed in the two vectors. In one vector the homologous G. cingulata gpdA promoter controlled hygromycin B phosphotransferase expression (homologous truncation vector), whereas in the second vector promoter elements were from the Aspergillus nidulans gpdA gene (heterologous truncation vector). Following transformation with the homologous truncation vector, nine transformants were analysed by Southern hybridisation; no transformants contained a disrupted pnlA gene. Of nineteen heterologous truncation vector transformants, three contained a disrupted pnlA gene; Southern analysis revealed single integrations of vector sequence at pnlA in two of these transformants. pnlA mRNA was not detected by Northern hybridisation in pnlA-transformants. pnlA-transformants failed to produce a PNLA protein with a pI identical to one normally detected in wild-type isolates by silver and activity staining of isoelectric focussing gels. Pathogenesis on Capsicum and apple was unaffected by disruption of the pnlA gene, indicating that the corresponding gene product, PNLA, is not essential for pathogenicity. Gene disruption is a feasible method for selectively mutating defined loci in G. cingulata for functional analysis of the corresponding gene products. 相似文献
105.
Søren Bak Rachel Alice Kahn Carl Erik Olsen Barbara Ann Halkier 《The Plant journal : for cell and molecular biology》1997,11(2):191-201
Obtusifoliol 14β-demethylase from Sorghum bicolor (L.) Moench has been cloned using a gene-specific probe generated using PCR primers designed from an internal 14 amino acid sequence. The sequence identifies sorghum obtusifoliol 14α-demethylase as a cytochrome P450 and it is assigned to the CYP51 family together with the sterol 14α-demethylases from fungi and mammals. The presence of highly conserved regions in the amino acid sequences, analogous substrates and the same metabolic role demonstrate that the sterol 14α-demethylases are orthologous enzymes. The sterol 14α-demethylases catalyse an essential step in sterol biosynthesis as evidenced by the absence of a 14α-methyl group in all known functional sterols. A functional sorghum obtusifoliol 14α-demethylase was expressed at high levels in Escherichia coli and purified using an efficient method based on temperature-induced Triton X-114 phase partitioning. The recombinant purified enzyme produced a type I spectrum with obtusifoliol as substrate. Reconstitution of purified recombinant enzyme with sorghum NADPH—cytochrome P450 reductase in dilaurylphosphatidylcholine micelles confirms that obtusifoliol 14α-demethylase catalyses the 14α-demethylation of obtusifoliol to 4α-methyl-5α-ergosta-8,14,24(28)-trien-3β-ol as evidenced by GC—MS. The isolation of a cDNA clone encoding the plant sterol 14α-demethylase, combined with the previously isolated cDNA clones for fungal and mammalian sterol 14α-demethylases, provides an important tool in the rational design of specific inhibitors towards the individual sterol 14α-demethylases. 相似文献
106.
Charlotte Schou Erik R. Ottosen Hans Jørgen Petersen Fredrik Björkling Scilla Latini Pernille V. Hjarnaa Erik Bramm Lise Binderup 《Bioorganic & medicinal chemistry letters》1997,7(24):616-3100
4-Pyridyl cyanoguanidines with hydrophobic aromatic side chains showed potent antiproliferative activity in the human breast and lung cancer cell lines MCF-7, NYH and H460. In vivo, treatment with N-(6-chlorophenoxyhexyl)-N′-cyano-N″-4-pyridylguanidine (18, 20 mg/kg/day po.), gave a complete remission of tumours in a model of NYH inoculated nude mice. 相似文献
107.
Vertical displacement velocity of a Daphniagaleata × hyalina clone was quantified inrelation to changes in the relative rate of lightchange. An increase in the latter variable triggers anenhanced swimming response, and this response is againelicited when a second increase in the rate ofrelative light increase is applied. Decreases in therate of light increase affect phototactic swimming ina similar way. The acceleration/deceleration assistedstimulus-response system is an extension of the ideaof phototaxis as the underlying behavioural mechanismfor vertical migration, and suggests that continuousaccelerations in light change also affect verticaldisplacements observed in the field. A simple dielvertical migration simulation model was used tocalculate the vertical displacement of Daphniain relation to the natural light change at sunrise.The calculated vertical displacement fits nicely inthe temporal range of the observed averaged downwardmigration of adult Daphnia in Lake Maarsseveen.The calculated migration amplitude, however, islarger than the change in mean population depthobserved in nature. 相似文献
108.
Surface water chemistry characteristics in the Lake Storgrønningen drainage area, Høylandet, during periods of high and low discharge 总被引:2,自引:2,他引:0
The surface water chemistry of Høylandet has beenstudied by performing two synoptic surveys, duringhigh runoff in the autumn of 1986 and during a lowflow period in the summer of 1988. Based on watersamples of up to 38 chemical variables from 75 sites,analyses show considerable variation in the chemicalcomposition. There is a strong altitude gradient, i.e.very dilute poorly buffered waters dominate at higherelevations near the timberline while progressivelyhigher salt content and alkalinities arecharacteristic at lower altitudes more dominated byforests. The influence of mires is less pronounced.The overall water quality is of oligotrophic naturewith low concentrations of strong acid anions andmetals known to be enriched under acidifiedconditions. The natural pH gradients are considerablebut with no indication of anthropogenic acidification.The data provide little support for the hypothesisthat in-catchment production of organically derivedacidity leads to acid runoff, which in thesecatchments appears compensated by increasedweathering. The findings are in general accordancewith other Høylandet catchment studies. It isconcluded that this area may serve as a representativepristine surface runoff analogue for catchmentscurrently affected by atmospheric deposition of strongmineral acids. 相似文献
109.
Batch experiments were carried out to investigate the stoichiometry and kinetics of microbial degradation of toluene under denitrifying conditions. The inoculum originated from a mixture of sludges from sewage treatment plants with alternating nitrification and denitrification. The culture was able to degrade toluene under anaerobic conditions in the presence of nitrate, nitrite, nitric oxide, or nitrous oxide. No degradation occurred in the absence of Noxides. The culture was also able to use oxygen, but ferric iron could not be used as an electron acceptor. In experiments with14C-labeled toluene, 34%±8% of the carbon was incorporated into the biomass, while 53%±10% was recovered as14CO2, and 6%±2% remained in the medium as nonvolatile water soluble products. The average consumption of nitrate in experiments, where all the reduced nitrate was recovered as nitrite, was 1.3±0.2 mg of nitrate-N per mg of toluene. This nitrate reduction accounted for 70% of the electrons donated during the oxidation of toluene. When nitrate was reduced to nitrogen gas, the consumption was 0.7±0.2 mg per mg of toluene, accounting for 97% of the donated electrons. Since the ammonia concentration decreased during degradation, dissimilatory reduction of nitrate to ammonia was not the reductive process. The degradation of toluene was modelled by classical Monod kinetics. The maximum specific rate of degradation, k, was estimated to be 0.71 mg toluene per mg of protein per hour, and the Monod saturation constant, K
s
, to be 0.2 mg toluene/l. The maximum specific growth rate,
max
, was estimated to be 0.1 per hour, and the yield coefficient, Y, was 0.14 mg protein per mg toluene.Abbreviations NVWP
Non Volatile Water-soluble Products 相似文献
110.
Removal of toluene in waste gases using a biological trickling filter 总被引:12,自引:0,他引:12
The removal of toluene from waste gas was studied in a trickling biofilter. A high level of water recirculation (4.7 m h–1) was maintained in order to keep the liquid phase concentration constant and to achieve a high degree of wetting. For loads in the range from 6 to 150 g m–3 h–1 the maximum volumetric removal rate (elimination capacity) was 35±10 g m–3 h–1, corresponding to a zero order removal rate of 0.11±0.03 g m–2 h–1 per unit of nominal surface area. The surface removal was zero order above the liquid phase concentrations of approximately 1.0 g m–3, corresponding to inlet gas concentrations above 0.7–0.8 g m–3. Below this concentration the surface removal was roughly of first order. The magnitude of the first order surface removal rate constant, k1A
, was estimated to be 0.08–0.27 m h–1 (k1A
a=24–86 h–1). Near-equilibrium conditions existed in the gas effluent, so mass transfer from gas to liquid was obviously relatively fast compared to the biological degradation. An analytical model based on a constant liquid phase concentration through the trickling filter column predicts the effluent gas concentration and the liquid phase concentration for a first and a zero order surface removal. The experimental results were in reasonable agreement with a very simple model valid for conditions with an overall removal governed by the biological degradation and independent of the gas/liquid mass transfer. The overall liquid mass transfer coefficient, KLa, was found to be a factor 6 higher in the system with biofilm compared to the system without. The difference may be explained by: 1. Difference in the wetting of the packing material, 2. Mass transfer occurring directly from the gas phase to the biofilm, and 3. Enlarged contact area between the gas phase and the biofilm due to a rough biofilm surface. 相似文献