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Biomedical subjects

R Amann

Publications and source records attributed to R Amann.

At least 19 recordsLinked to original sources

[Disseminated cryptococosis in renal transplant recipient].

The incidence of cryptococosis ranges from 0.4-5.8% in renal transplant. Meningitis is the principal clinical manifestation, frequently with a subacute curse. In renal transplantation recipients, disseminated cryptococcosis appears as the more frequent presentation. We report a case of a 32 years old woman renal transplant recipient who presents altered mental status, headache and tremor during the month before her assessment to our hospital. Microbiological study was performed in cerebrospinal fluid and cryptococcus was isolated. She was treated with amphotericin B and 5 flucytosine. She developed refractory increased intracranial pressure and a lumboperitoneal derivation was necessary. Cryptococcosis must be considered as cause of meningitis in patients with renal transplant. The early diagnosis and treatment are fundamental due to high mortality of this pathology.

Adult↗

Nitrification in freshwater sediments as influenced by insect larvae: quantification by microsensors and fluorescence in situ hybridization.

Sediment-reworking macrofauna can stimulate nitrification by increasing the O(2) penetration into sediments or it can reduce nitrification by grazing on nitrifying bacteria. We investigated the influence of Chironomus riparius larvae (Insecta: Diptera) on the in situ activity, abundance, and distribution of NH4+-oxidizing (AOB) and NO2--oxidizing bacteria (NOB) in two freshwater sediments with microsensors and fluorescence in situ hybridization. In organic-poor sediment, nitrification activity was reduced by the presence of C. riparius larvae, whereas no such effect was detected in organic-rich sediment. We explain this difference with the variable larval burrowing and grazing behavior in the two sediment types: In organic-poor sediment larval activities were intense and evenly distributed across the whole sediment surface, whereas in organic-rich sediment larval activities were locally restricted to the microenvironment of animal burrows. Surprisingly, the animals did not cause any significant change of the abundance of AOB and NOB. This implies that the observed reduction of nitrification activity was not density-regulated, but rather was due to the lowered metabolic activity of the nitrifiers. Partial digestion and redeposition of particle-associated bacteria by C. riparius larvae are believed to have caused this loss of metabolic activity.

Animals↗

Identification of planctomycetes with order-, genus-, and strain-specific 16S rRNA-targeted probes.

A specific 16S rRNA-targeted oligonucleotide probe (PIR1223) for the genus Pirellula and a species-specific probe (RB454) for Pirellula sp. strain SH1 have been designed and optimized. Together with the already existing order-specific probe PLA886, the two newly designed probes were used to detect and identify planctomycetes, pirellulae, and close relatives of Pirellula sp. strain SH1 in different habitats. With the help of these probes for detection and identification, bacteria of the genus Pirellula were detected and cultivated from tissue of the Mediterranean sponge Aplysina aerophoba and from the water column of the Kiel Fjord. An unexpected result was the close phylogenetic relationship of the isolate from the sponge and the brackish water habitat Kiel Fjord as revealed by DNA/DNA hybridization.

Animals↗

The genome of Desulfotalea psychrophila, a sulfate-reducing bacterium from permanently cold Arctic sediments.

Desulfotalea psychrophila is a marine sulfate-reducing delta-proteobacterium that is able to grow at in situ temperatures below 0 degrees C. As abundant members of the microbial community in permanently cold marine sediments, D. psychrophila-like bacteria contribute to the global cycles of carbon and sulfur. Here, we describe the genome sequence of D. psychrophila strain LSv54, which consists of a 3 523 383 bp circular chromosome with 3118 predicted genes and two plasmids of 121 586 bp and 14 663 bp. Analysis of the genome gave insight into the metabolic properties of the organism, e.g. the presence of TRAP-T systems as a major route for the uptake of C(4)-dicarboxylates, the unexpected presence of genes from the TCA cycle, a TAT secretion system, the lack of a beta-oxidation complex and typical Desulfovibrio cytochromes, such as c(553), c(3) and ncc. D. psychrophila encodes more than 30 two-component regulatory systems, including a new Ntr subcluster of hybrid kinases, nine putative cold shock proteins and nine potentially cold shock-inducible proteins. A comparison of D. psychrophila's genome features with those of the only other published genome from a sulfate reducer, the hyperthermophilic archaeon Archaeoglobus fulgidus, revealed many striking differences, but only a few shared features.

Arctic Regions↗

[Scrotal oedema in a kidney graft recipient].

A 54-year old man received a cadaveric renal allograf for end-stage renal disease due to membranous nephropathy. The patient developed scrotal oedema, 14 days after renal transplantation. The biochemical analysis of scrotal fluid after surgical drainage demostrated urine. Helical computed tomography was performed and it showed contrast leaks in medial, distal ureter and bladder. The urinary fistula was treated with surgical repairment and catheter endoluminal of ureter which was retired in four weeks. The incidence of urinary fistula ranged from 3 to 9%. The scrotal or perineal oedema is unusual clinical presentation of urinary leaks. The diagnosis of urinary fistula may be difficult and depends on a high degree of clinical suspicion. The helical computed tomography is a technique which allows a high resolution three-dimensional reconstruction and it can be used to make the diagnosis of urinary fistula.

Edema↗

Complete genome sequence of the marine planctomycete Pirellula sp. strain 1.

Pirellula sp. strain 1 ("Rhodopirellula baltica") is a marine representative of the globally distributed and environmentally important bacterial order Planctomycetales. Here we report the complete genome sequence of a member of this independent phylum. With 7.145 megabases, Pirellula sp. strain 1 has the largest circular bacterial genome sequenced so far. The presence of all genes required for heterolactic acid fermentation, key genes for the interconversion of C1 compounds, and 110 sulfatases were unexpected for this aerobic heterotrophic isolate. Although Pirellula sp. strain 1 has a proteinaceous cell wall, remnants of genes for peptidoglycan synthesis were found. Genes for lipid A biosynthesis and homologues to the flagellar L- and P-ring protein indicate a former Gram-negative type of cell wall. Phylogenetic analysis of all relevant markers clearly affiliates the Planctomycetales to the domain Bacteria as a distinct phylum, but a deepest branching is not supported by our analyses.

Adaptation, Physiological↗

Substance P in the uterine cervix, dorsal root ganglia and spinal cord during pregnancy and the effect of estrogen on SP synthesis.

Prior to parturition the non-pliable uterine cervix undergoes a ripening process ("softens" and dilates) to allow a timely passage of the fetus at term. The exact mechanism(s) triggering and involved in cervical ripening are unknown, though evidence for a role for sensory neurons and their contained neuropeptides is emerging. Moreover, an apparent increase in neuropeptide immunoreactive nerves occurs in the cervix during pregnancy, maternal serum estrogen levels rise at term and uterine cervix-related L6-S1 dorsal root ganglia (DRG) sensory neurons express estrogen receptor (ER) and neuropeptides. Thus, we sought to test the hypothesis that the neuropeptide substance P (SP) changes biosynthesis and release over pregnancy, that estrogen, acting via the ER pathway, increases synthesis of SP in DRG, and that SP is utilized in cervical ripening at late pregnancy. Using immunohistochemistry, in situ hybridization, reverse transcriptase-polymerase chain reaction (RT-PCR) and radioimmunoassay (RIA), we investigated coexpression of ER-alpha/beta and SP; differential expression of ER-alpha and -beta mRNA in DRG neurons; SP synthesis in DRG; and changes in SP concentration in the cervix, DRG and spinal cord over pregnancy. In addition, the effect of exogenous estrogen on SP synthesis in L6-S1 DRG of ovariectomized rats was examined. SP-immunoreactive neurons expressed ER-alpha and ER-beta. SP synthesis (expressed as beta-PPT mRNA label) was prominent in small DRG neurons. SP concentration increased in the L6-S1 DRG and spinal cord segments, with a peak at Day 20 of gestation, but decreased in the cervix during the first two trimesters, with a rise over the last trimester to Day 10 levels. SP and ER-alpha mRNA synthesis increased in DRG over pregnancy but ER-beta mRNA levels were largely unchanged. When ovariectomized rats were treated with exogenous estrogen, SP mRNA synthesis in the DRG increased in a dose-related manner, an effect blocked by ER blocker ICI 182 780. From these results, we postulate that synthesis of SP in L6-S1 DRG and utilization in the cervix increase over pregnancy and this synthesis is under influence of the estrogen-ER system, most likely ER-alpha. We postulate that SP may play a role in cervical ripening and, consequently in the birth process.

Animals↗

Effect of endotoxin treatment on the expression of cyclooxygenase-2 and prostaglandin synthases in spinal cord, dorsal root ganglia, and skin of rats.

Peripheral inflammation causes upregulation of cyclooxygenase in the spinal cord and subsequent increase in prostaglandin biosynthesis. However, prostaglandin synthases, which are downstream of cyclooxygenase control the type of prostaglandin that is formed predominantly. Since there is little known about the regulation of prostaglandin synthases, the present study was conducted in order to determine the effect of endotoxin treatment on the expression of messenger RNA encoding interleukin 1beta, cyclooxygenase-2, and prostaglandin synthases mediating the formation of prostaglandin E(2) (membrane bound prostaglandin E synthase) and prostaglandin D(2) (lipocalin prostaglandin D synthase) in spinal cord, dorsal root ganglia and skin of rats. Endotoxin (2 mg/kg i.p.) induced the expression of interleukin-1beta, cyclooxygenase-2, and membrane bound prostaglandin E synthase messenger RNA in spinal cord, dorsal root ganglia, and skin as determined by reverse transcription polymerase chain reaction. In contrast, basal expression of lipocalin prostaglandin D synthase messenger RNA in spinal cord and dorsal root ganglia was not significantly altered by endotoxin. Dexamethasone (1 mg/kg s.c. at -18 h and -1 h) attenuated the effect endotoxin on the expression of interleukin-1beta, cyclooxygenase-2, and membrane bound prostaglandin E synthase messenger RNA in all tissues investigated, but did not significantly influence expression of lipocalin prostaglandin D synthase mRNA in spinal cord and dorsal root ganglia. In situ hybridisation histochemistry showed endotoxin-induced expression of cyclooxygenase-2 and membrane bound prostaglandin E synthase messenger RNA throughout gray and white matter of spinal cord sections. In dorsal root ganglia, expression of membrane bound prostaglandin E synthase seemed primarily located to non-neuronal cells, while cyclooxygenase-2 messenger RNA was not detectable. The results show that the immune response elicited by endotoxin induced cyclooxygenase-2 and membrane bound prostaglandin E synthase, but not lipocalin prostaglandin D synthase messenger RNA in spinal cord and dorsal root ganglia of rats. The distribution of cyclooxygenase-2 and membrane bound prostaglandin E synthase messenger RNA expressing cells suggests major involvement of non-neuronal cells in spinal prostaglandin biosynthesis. Determination of the regulation of enzymes downstream of cyclooxygenase at the messenger RNA level may represent a valuable tool to investigate effects of analgesic/anti-inflammatory drugs on the regulation of spinal prostaglandin biosynthesis.

Animals↗

Microbial ecology of an extreme acidic environment, the Tinto River.

The Tinto River (Huelva, southwestern Spain) is an extreme environment with a rather constant acidic pH along the entire river and a high concentration of heavy metals. The extreme conditions of the Tinto ecosystem are generated by the metabolic activity of chemolithotrophic microorganisms thriving in the rich complex sulfides of the Iberian Pyrite Belt. Molecular ecology techniques were used to analyze the diversity of this microbial community. The community's composition was studied by denaturing gradient gel electrophoresis (DGGE) using 16S rRNA and by 16S rRNA gene amplification. A good correlation between the two approaches was found. Comparative sequence analysis of DGGE bands showed the presence of organisms related to Leptospirillum spp., Acidithiobacillus ferrooxidans, Acidiphilium spp., "Ferrimicrobium acidiphilum," Ferroplasma acidiphilum, and Thermoplasma acidophilum. The different phylogenetic groups were quantified by fluorescent in situ hybridization with a set of rRNA-targeted oligonucleotide probes. More than 80% of the cells were affiliated with the domain Bacteria, with only a minor fraction corresponding to Archaea. Members of Leptospirillum ferrooxidans, Acidithiobacillus ferrooxidans, and Acidiphilium spp., all related to the iron cycle, accounted for most of the prokaryotic microorganisms detected. Different isolates of these microorganisms were obtained from the Tinto ecosystem, and their physiological properties were determined. Given the physicochemical characteristics of the habitat and the physiological properties and relative concentrations of the different prokaryotes found in the river, a model for the Tinto ecosystem based on the iron cycle is suggested.

DNA Fingerprinting↗

Inhibition of prostaglandin biosynthesis in human endotoxin-stimulated peripheral blood monocytes: effects of caffeine.

There is an ongoing debate about possible advantages of the coadministration of caffeine with cyclooxygenase (COX) inhibitors in the treatment of pain. There are results suggesting interference by caffeine with COX expression and activity in rat immune cells. In the present study, we have used, therefore, human endotoxin-stimulated monocytes to investigate a possible influence of caffeine on indometacin-induced inhibition of prostaglandin E(2) (PGE(2)) formation. Endotoxin caused a concentration- and time-dependent increase in immunoreactive PGE(2) that was dependent on CD14-mediated mechanisms. In order to investigate pharmacological inhibition of the COX activity, a submaximal concentration of 1 ng/ml endotoxin (4 h exposure time) was used. Indometacin caused a concentration-dependent inhibition of PGE(2) with an apparent IC(50) of 8.9 +/- 1.4 x 10(-9) mol/l and an I(max) of 1 x 10(-7) mol/l. Caffeine (5 x 10(-6) to 1.5 x 10(-4) mol/l) on its own produced no statistically significant effect on endotoxin-induced PGE(2) formation. In the presence of caffeine (5 x 10(-6) to 1.5 x 10(-4) mol/l), inhibition of PGE(2) biosynthesis by indometacin (1 x 10(-8) mol/l) was not significantly altered. These results show that, in human monocytes, caffeine, up to concentrations severalfold higher than those reached in patients, has no significant effect on endotoxin-induced PGE(2) formation nor on its inhibition by indometacin.

Caffeine↗

Simultaneous P and N removal in a sequencing batch biofilm reactor: insights from reactor- and microscale investigations.

A sequencing batch biofilm reactor (SBBR) with well established enhanced biological phosphate removal (EBPR) was subjected to higher ammonium concentrations to stimulate and eventually implement simultaneous nitrification. Changes of activity and populations were investigated by a combination of online monitoring, microsensor measurements and fluorescence in situ hybridisation (FISH) of biofilm sections. Nitrification and nitrifying bacteria were always restricted to the periodically oxic biofilm surface. Both, activity and population size increased significantly with higher ammonium concentrations. Nitrification always showed a delay after the onset of aeration, most likely due to competition for oxygen by coexisting P accumulating and other heterotrophic bacteria during the initial aeration phase. This view is also supported by comparing oxygen penetration and oxygen uptake rates under low and high ammonium conditions. Therefore, simultaneous nitrification and phosphorus removal in a P removing SBBR appears to be only possible with a sufficiently long oxic period to ensure oxygen availability for nitrifiers.

Bacteria↗

Sodium salicylate enhances the expression of cyclooxygenase-2 in endotoxin-stimulated human mononuclear cells.

The effects of salicylate on the expression of cyclooxygenases, and on prostaglandin E(2) biosynthesis were examined in human peripheral blood mononuclear cells. Peripheral blood mononuclear cells were incubated in the presence of endotoxin, which induced expression of cyclooxygenase-2 protein, and caused a time-dependent increase of immunoreactive prostaglandin E(2) in the supernatant. The cycooxygenase-2 selective inhibitor N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide (NS-398, 1 microM) suppressed the endotoxin-induced increase of prostaglandin E(2), without significantly affecting the expression of cyclooxygenase-1 or cyclooxygenase-2. In peripheral blood mononuclear cells exposed to endotoxin (18 h), 1.0 and 3.0 mM sodium salicylate reduced the prostaglandin E(2) concentration of the supernatant, and, at the same time, stimulated cyclooxygenase-2 expression. After a subsequent 2 h incubation of peripheral blood mononuclear cells in drug-free medium, prostaglandin E(2) concentrations in samples that had been exposed to endotoxin together with 1.0 or 3.0 mM salicylate were significantly higher than in samples exposed to endotoxin alone. These results show that salicylate can enhance the expression of cyclooxygenase-2 in endotoxin-exposed peripheral blood mononuclear cells and at the same time reduce prostaglandin E(2) formation. After washout and removal of salicylate-induced cyclooxygenase inhibition, increased cyclooxygenase-2 expression resulted in enhanced prostaglandin E(2) formation. It seems possible that under certain conditions salicylate-induced stimulation of cyclooxygenase-2 expression may contribute to its clinical pharmacological profile.

Cyclooxygenase 2↗

Utilization of tmRNA sequences for bacterial identification.

BACKGROUND: Ribosomal RNA molecules are widely used for phylogenetic and in situ identification of bacteria. Nevertheless, their use to distinguish microorganisms within a species is often restricted by the high degree of sequence conservation and limited probe accessibility to the target in fluorescence in situ hybridization (FISH). To overcome these limitations, we examined the use of tmRNA for in situ identification. In E. coli, this stable 363 nucleotides long RNA is encoded by the ssrA gene, which is involved in the degradation of truncated proteins. RESULTS: Conserved sequences at the 5'- and 3'-ends of tmRNA genes were used to design universal primers that could amplify the internal part of ssrA from Gram-positive bacteria having low G+C content, i.e. genera Bacillus, Enterococcus, Lactococcus, Lactobacillus, Leuconostoc, Listeria, Streptococcus and Staphylococcus. Sequence analysis of tmRNAs showed that this molecule can be used for phylogenetic assignment of bacteria. Compared to 16S rRNA, the tmRNA nucleotide sequences of some bacteria, for example Listeria, display considerable divergence between species. Using E. coli as an example, we have shown that bacteria can be specifically visualized by FISH with tmRNA targeted probes. CONCLUSIONS: Features of tmRNA, including its presence in phylogenetically distant bacteria, conserved regions at gene extremities and a potential to serve as target for FISH, make this molecule a possible candidate for identification of bacteria.

Bacteria↗

Endosymbiotic sulphate-reducing and sulphide-oxidizing bacteria in an oligochaete worm.

Stable associations of more than one species of symbiont within a single host cell or tissue are assumed to be rare in metazoans because competition for space and resources between symbionts can be detrimental to the host. In animals with multiple endosymbionts, such as mussels from deep-sea hydrothermal vents and reef-building corals, the costs of competition between the symbionts are outweighed by the ecological and physiological flexibility gained by the hosts. A further option for the coexistence of multiple symbionts within a host is if these benefit directly from one another, but such symbioses have not been previously described. Here we show that in the gutless marine oligochaete Olavius algarvensis, endosymbiotic sulphate-reducing bacteria produce sulphide that can serve as an energy source for sulphide-oxidizing symbionts of the host. Thus, these symbionts do not compete for resources but rather share a mutalistic relationship with each other in an endosymbiotic sulphur cycle, in addition to their symbiotic relationship with the oligochaete host.

Aerobiosis↗

Effects of COX-1 and COX-2 inhibitors on eicosanoid biosynthesis and the release of substance P from the guinea-pig isolated perfused lung.

OBJECTIVE: In the guinea-pig isolated perfused lung, co-administration of bradykinin (BK) and histamine causes the release of pro-inflammatory neuropeptides, an effect that is largely dependent on BK-induced formation of prostaglandins. Since it is known that at least two isoenzymes, cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) catalyse the conversion of arachidonic acid to prostaglandins (PGs) and thromboxanes, the present study aimed at investigating the effect of selective COX-1 and COX-2 inhibitors on the evoked release of substance P (SP). MATERIAL AND METHODS: Lungs were vascularly perfused with oxygenated physiological salt solution containing peptidase inhibitors. BK (0.1 microM) and histamine (100 microM) were added to the perfusate for 10 min and 5 min, respectively. The concentrations of 6-keto-PGF1alpha, cysteinyl-leukotriene (LT), and SP were determined in the outflow by radioimmunoassay. RESULTS: In non-stimulated preparations, indomethacin (2 microM) and the selective COX-1 inhibitor SC-560 (0.03-1 microM) reduced basal release of 6-keto-PGF1alpha, without significantly affecting the release of cysteinyl-LT and SP. The selective COX-2 inhibitors NS-398 (1 microM) or DFU (10 microM) had no significant effect on the basal release of eicosanoids or SP. Co-administration of BK and histamine caused a pronounced increase in the concentration of 6-keto-PGF1alpha and cysteinyl-LT, and SP in the effluate. Under these conditions, indomethacin as well as SC-560 reduced the release of 6-keto-PGF1alpha, enhanced cysteinyl-LT release, and attenuated the release of SP. In contrast, the selective COX-2 inhibitors NS 398 and DFU had no significant effect on the stimulated release of eicosanoids or SP. CONCLUSIONS: These results suggest that in the isolated guinea-pig lung, basal prostanoid biosynthesis as well as BK-induced stimulation of prostanoid formation and subsequent facilitation of histamine-induced SP release is primarily mediated by COX-1 without detectable involvement of COX-2.

6-Ketoprostaglandin F1 alpha↗

The identification of microorganisms by fluorescence in situ hybridisation.

Fluorescence in situ hybridisation (FISH) with rRNA-targeted oligonucleotide probes facilitates the rapid and specific identification of individual microbial cells in their natural environments. Over the past year there have been a number of methodological developments in this area and new applications of FISH in microbial ecology and biotechnology have been reported.

Bacteria↗

Effects of terbutaline on NGF formation in allergic inflammation of the rat.

1. The aim of this study was to determine the effects of the beta adrenergic agonist terbutaline on NGF increase caused by allergic inflammation in rats. 2. Intraplantar antigen injection in sensitized rats increased paw volume and stimulated NGF biosynthesis in the skin of the injected paw as determined 3 and 6 h after injection. Treatment of rats with terbutaline (0.1 - 0.3 mg kg(-1), s.c.) had no significant effect on the NGF concentration in non-inflamed skin, but reduced oedema, and at 0.3 mg kg(-1) also NGF mRNA and immunoreactive NGF in the skin of the inflamed paw in a propranolol-reversible manner. In carrageenan-induced inflammation, terbutaline did not significantly reduce the inflammation-induced increase of NGF in paw skin. 3. Exposure of sensitized rats to aerosolized antigen (twice, 24 h interval) increased protein content, eosinophil leukocytes, and immunoreactive NGF in the bronchoalveolar lavage fluid (BAL, obtained 16 h after the second antigen exposure). Treatment of rats with terbutaline (0.3 mg kg(-1), s.c. 30 min before the second antigen challenge) suppressed antigen-induced elevation of protein and eosinophil leukocytes, and reduced the concentration of NGF in BAL to values similar to those found in non-sensitized rats. 4. The present results demonstrate anti-allergic properties of terbutaline in rats that were accompanied by a marked reduction of antigen-induced NGF increase in skin and BAL, respectively. These results are compatible with the assumption that terbutaline primarily suppressed the immune response to antigen thereby attenuating the release of vasoactive mediators and the stimulation of NGF biosynthesis.

Adrenergic beta-Agonists↗

Linking the composition of bacterioplankton to rapid turnover of dissolved dimethylsulphoniopropionate in an algal bloom in the North Sea.

The algal osmolyte, dimethylsulphoniopropionate (DMSP), is abundant in the surface oceans and is the major precursor of dimethyl sulphide (DMS), a gas involved in global climate regulation. Here, we report results from an in situ Lagrangian study that suggests a link between the microbially driven fluxes of dissolved DMSP (DMSPd) and specific members of the bacterioplankton community in a North Sea coccolithophore bloom. The bacterial population in the bloom was dominated by a single species related to the genus Roseobacter, which accounted for 24% of the bacterioplankton numbers and up to 50% of the biomass. The abundance of the Roseobacter cells showed significant paired correlation with DMSPd consumption and bacterioplankton production, whereas abundances of other bacteria did not. Consumed DMSPd (28 nM day(-1)) contributed 95% of the sulphur and up to 15% of the carbon demand of the total bacterial populations, suggesting the importance of DMSP as a substrate for the Roseobacter-dominated bacterioplankton. In dominating DMSPd flux, the Roseobacter species may exert a major control on DMS production. DMSPd turnover rate was 10 times that of DMS (2.7 nM day(-1)), indicating that DMSPd was probably the major source of DMS, but that most of the DMSPd was metabolized without DMS production. Our study suggests that single species of bacterioplankton may at times be important in metabolizing DMSP and regulating the generation of DMS in the sea.

Alphaproteobacteria↗