Individual Physiological Adaptations Enable Selected Bacterial Taxa To Prevail during Long-Term Incubations.

Enclosure experiments are frequently used to investigate the impact of changing environmental conditions on microbial assemblages. Yet, how the incubation itself challenges complex bacterial communities is thus far unknown. In this study, metaproteomic profiling, 16S rRNA gene analyses, and cell counts were combined to evaluate bacterial communities derived from marine, mesohaline, and oligohaline conditions after long-term batch incubations. Early in the experiment, the three bacterial communities were highly diverse and differed significantly in their compositions. Manipulation of the enclosures with terrigenous dissolved organic carbon resulted in notable differences compared to the control enclosures at this early phase of the experiment. However, after 55 days, bacterial communities in the manipulated and the control enclosures under marine and mesohaline conditions were all dominated by gammaproteobacterium Spongiibacter In the oligohaline enclosures, actinobacterial cluster I of the hgc group (hgc-I) remained abundant in the late phase of the incubation. Metaproteome analyses suggested that the ability to use outer membrane-based internal energy stores, in addition to the previously described grazing resistance, may enable the gammaproteobacterium Spongiibacter to prevail in long-time incubations. Under oligohaline conditions, the utilization of external recalcitrant carbon appeared to be more important (hgc-I). Enclosure experiments with complex natural microbial communities are important tools to investigate the effects of manipulations. However, species-specific properties, such as individual carbon storage strategies, can cause manipulation-independent effects and need to be considered when interpreting results from enclosures.IMPORTANCE In microbial ecology, enclosure studies are often used to investigate the effect of single environmental factors on complex bacterial communities. However, in addition to the manipulation, unintended effects ("bottle effect") may occur due to the enclosure itself. In this study, we analyzed the bacterial communities that originated from three different salinities of the Baltic Sea, comparing their compositions and physiological activities both at the early stage and after 55 days of incubation. Our results suggested that internal carbon storage strategies impact the success of certain bacterial species, independent of the experimental manipulation. Thus, while enclosure experiments remain valid tools in environmental research, microbial community composition shifts must be critically followed. This investigation of the metaproteome during long-term batch enclosures expanded our current understanding of the so-called "bottle effect," which is well known to occur during enclosure experiments.

Differential responses of marine, mesohaline and oligohaline bacterial communities to the addition of terrigenous carbon.

In response to global warming, increasing quantities of tDOM are transported through estuaries from land to the sea. In this study, we investigated microbial responses to increased tDOM concentrations in three salinity regimes (salinity: 32, 7 and 3) characteristic of the Baltic Sea. Mesocosm experiments performed in May and November revealed low (0-6%) dissolved organic carbon (DOC) utilisation. Molecular DOM analyses using ultrahigh-resolution mass spectrometry identified the terrigenous signal in the tDOM manipulation, but the molecular changes in DOM levels over the course of the experiment were subtle. However, tDOM had significant stimulatory effects on bacterial production in the oligohaline mesocosms. The shift in the bacterial community composition was especially prominent in the tDOM-amended marine and mesohaline mesocosms, but not in the oligohaline mesocosms after 7 and 11 days of incubation. These results suggested the inherent ability of oligohaline bacterial communities to adapt to high tDOM concentrations and therefore to use tDOM. The higher rates of bacterial activity and DOC removal in mesocosms containing UV-pretreated tDOM supported the increased bioavailability of photoinduced, modified tDOM. The overall low rates of microbial tDOM utilisation highlights the importance of abiotic factors in determining the distribution and dynamics of tDOM in estuaries.

Biological manganese-dependent sulfide oxidation impacts elemental gradients in redox-stratified systems: indications from the Black Sea water column.

The reduction of manganese oxide with sulfide in aquatic redox-stratified systems was previously considered to be mainly chemical, but recent isolation of the Black Sea isolate Candidatus Sulfurimonas marisnigri strain SoZ1 suggests an important role for biological catalyzation. Here we provide evidence from laboratory experiments, field data, and modeling that the latter process has a strong impact on redox zonation in the Black Sea. High relative abundances of Sulfurimonas spp. across the redoxcline in the central western gyre of the Black Sea coincided with the high-level expression of both the sulfide:quinone oxidoreductase gene (sqr, up to 93% expressed by Sulfurimonas spp.) and other sulfur oxidation genes. The cell-specific rate of manganese-coupled sulfide oxidation by Ca. S. marisnigri SoZ1 determined experimentally was combined with the in situ abundance of Sulfurimonas spp. in a one-dimensional numerical model to calculate the vertical sulfide distribution. Abiotic sulfide oxidation was too slow to counterbalance the sulfide flux from euxinic water. We conclude that microbially catalyzed Mn-dependent sulfide oxidation influences the element cycles of Mn, S, C, and N and therefore the prevalence of other functional groups of prokaryotes (e.g., anammox bacteria) in a sulfide-free, anoxic redox zone.

[Follow-up examination and probatory CPAP therapy of obstructive sleep apnoea increase the long-term compliance]. / Poststationäre Nachsorge und probatorische CPAP-Therapie schlafbezogener obstruktiver Atemstörungen steigern die Langzeitcompliance.

INTRODUCTION: Since the implementation of CPAP therapy in the treatment of obstructive sleep apnoea in the 1980 s researchers have been looking for predictors and possibilities to improve long-term compliance. In a prospective randomised trial we examined the influence of a follow-up examination two weeks after the start of probatory CPAP therapy compared to immediate prescription of the CPAP device. METHODS: 249 new patients with a newly diagnosed obstructive sleep apnoea (OSA) started with a CPAP therapy. These patients were prospectively randomised depending on the dates of admission (even/uneven). The CPAP device for the first group was immediately prescribed. Patients of the second group were seen in our sleep laboratory ambulance after a probatory usage of the CPAP therapy over a period of fourteen days. After 433 +/- 138 days we measured the compliance by reading off the operating hours counter. In order to collect these data all patients received written simple instructions how to read off the operating hours counter. They sent back the results via a prepaid return envelope. In addition, we obtained the information as to whether a hot water bath humidifier was used. RESULTS: 171 of the initially 249 patients sent back the evaluation form. The randomisation of the groups was successful concerning: age, sex as well as the apnoea-hypopnoea index before and under CPAP therapy. 226 patients were treated with the fix-CPAP mode (mean pressure 8.1 +/- 1.8 cm H(2)O), 23 patients received auto CPAP therapy. The patients with a probatory CPAP therapy and follow-up examination showed a significantly (p = 0.01) better compliance of nocturnal CPAP use with 4.5 +/- 1.8 h/night versus those who had their CPAP device immediately prescribed with a use of 3.8 +/- 2.1 h/night. The percentage of patients with a use of CPAP more than 4 h/night was significantly higher in the group with probatory therapy (66.3 % vs. 45.6 %; p = 0.008). Patients with probatory CPAP therapy made more use of humidifiers than the immediate prescription group; however, the use of a humidifier did not have any significant influence on the long-term compliance (p = 0.58). CONCLUSION: The combination of probatory CPAP therapy and follow-up examination increases the long-term compliance significantly in the treatment of obstructive sleep apnoea.

A new formulation concept for drugs with poor water solubility for parenteral application.

The parenteral application of active substances with poor solubility in water is often bound to the use of stabilizing excipients or surfactants with serious undesired side effects. A new concept is introduced based on a drug concentrate, comprising the active substance dissolved in parenterally acceptable organic solvents, and an aqueous dilution medium, which are mixed in a special mixing device immediately prior to application and thus generating the applicable formulation directly prior to administration. Due to the requirement of formulation stability for only a few minutes, the amount of stabilizing agents can be reduced significantly. It can be shown that model drugs dissolved in a mixture of polyoxyethylen glycol, ethanol and soya lecithin as stabilizer may be mixed to an aqueous glucose solution resulting in a parenterally acceptable and administerable dispersion which is physically stable for several minutes. First in vivo data show good tolerability and blood plasma levels which are comparable to conventional solutions.

Immunoactivation enhances the concentration of luteinizing hormone-releasing hormone peptide and its gene expression in human peripheral T-lymphocytes.

An immunomodulatory role for LHRH was suggested when we reported the presence of immunoactive and bioactive LHRH and its mRNA in rat splenic and thymic lymphocytes. In this paper we report that human peripheral T-cells as well as its subsets CD4+ and CD8+ contained immunoactive and bioactive LHRH. Furthermore, analysis of phytohemagglutinin (PHA)-activated T-cell lysates for LHRH by RIA demonstrated that the mean concentration of LHRH in PHA-activated T-cells increased from 45 +/- 4.5 to 64 +/- 7 pg/10(6) cells after 24 h of culture and from 47 +/- 3.6 to 117 +/- 11.8 pg/10(6) cells (P < 0.01) after 48 h. While the LHRH concentration in PHA-activated cells increased over the last 24 h of culture h from 64 +/- 7 to 117 +/- 11.8 pg/10(6) cells (P < 0.001), there was no change in mean concentration of LHRH in T-cells kept in medium alone. In a preliminary study we found that fresh T-cells contain 20 +/- 1.4 pg pro-LHRH/10(6) cells, and PHA stimulation increased the pro-LHRH content similar to the increase in LHRH. As with unfractionated T-cells, a significant PHA-induced time-dependent enhancement of intracellular LHRH was noted in CD4+ and CD8+ T-cells. RNA extracted from lymphocytes was subjected to reverse transcription-polymerase chain reaction analysis using LHRH and histone-3.3, primers, the latter as an internal control. The polymerase chain reaction-generated data demonstrated that the relative amount of LHRH mRNA in cultured, but non-PHA-stimulated (resting), cells diminished dramatically between 5-24 h, but recovered by 48 h of culture. The relative amount of LHRH mRNA in PHA-stimulated cells revealed a markedly different pattern. LHRH message expression in PHA-activated cells increased slightly at 5 h of culture and was maximally stimulated by 24 h, but declined by 48 h of culture. The PHA activation-induced time-dependent enhancement of intracellular accumulation of LHRH peptide at 5 and 24 h was accompanied by increased LHRH message. However, the increased concentration of LHRH peptide at 48 h coincided with decreased LHRH message expression. The data from total protein synthesis in PHA-activated cells showed a progressive increase in protein synthesis, a pattern entirely similar to the changes in the cell content of LHRH.(ABSTRACT TRUNCATED AT 400 WORDS)

The Influence of Preculture Conditions and Food Quality on the Ingestion and Digestion Process of Three Species of Heterotrophic Nanoflagellates.

The influence of prey characteristics such as motility and size as well as of predator characteristics such as satiation and preculturing diet on the feeding process of interception feeding heterotrophic nanoflagellates was investigated. Three species of gram-negative bacteria, one species of gram-positive bacteria, two species of cyanobacteria (Synechococcus) and inert latex particles were fed as prey particles for three species of heterotrophic nanoflagellates (Spumella, Ochromonas, Cafeteria). Ingestion rates depended on the satiation of the flagellates and especially on the filling status of the food vacuoles. In addition, the ingestion rates depended on the characteristics of the food particle and were modified by pre-culturing the flagellates on either Pseudomonas putida or Bacillus subtilis. Digestion was found to be particle-specific. Cyanobacteria were excreted a few minutes after ingestion whereas heterotrophic bacteria were stored and digested in the food vacuoles. The spectrum of ingested particles is not identical to that of digested particles and thus neither the diet of the flagellates nor their impact on bacterial communities can be calculated simply from food vacuole content. "Selective digestion" could be shown to be an important selection mechanism concerning natural food particles. The digestion strategies of Cafeteria on the one hand and Spumella and Ochromonas on the other hand may be an important factor to explain protozoan species composition and succession in the field. In addition to bacterial abundance and grazing pressure by metazooplankton, the bacterial speciescomposition as well as biochemical variations within bacterial species may influence protozoan species composition and abundance.

Toward totally endoscopic coronary artery surgery.

BACKGROUND: Here we explore a method of using robotics to reduce morbidity and mortality in conventional coronary surgery. METHODS: Using a robotic surgical system two surgeons completed five steps: (1) 80 synthetic suture exercises; (2) 76 left internal thoracic artery to left anterior descending (LIMA-to-LAD) on porcine hearts; (3) cadaveric port placement for assessing optimal access; (4) endoscopic stabilization in the live porcine model; and, finally (5) eight clinical LIMA-to-LADs performed robotically. RESULTS: After 70 hours training, mean dry lab times fell from 7.0 and 5.8 min to 5.7 and 5.1 min in the two surgeonstab series. Wet lab times fell from 40.1 and 28.5 min to 28.8 and 19.2 min. In the clinical series of eight patients there were no mortalities; all had uncomplicated postoperative recovery and all were angina free at 6-week follow-up. CONCLUSION: The learning curve for robotic training is short, and reproducible results can be achieved clinically, after appropriate training, resulting in real patient benefit.

Congenital oesophageal strictures due to cartilaginous rings.

Two cases of distal oesophageal stricture secondary to tracheo-bronchial remnants containing cartilage are presented. The clinical histories and radiographic appearances of these lesions are discussed as is the postulated embryogenesis. A characteristic finding, when present, is the linear collection of barium projecting horizontally from the area of stricture, representing respiratory epithelial ducts.

Dependence of O2 transfer conductance of red blood cells on cellular dimensions.

To estimate the significance of the dimensions of RBC on O2 transfer, the kinetics of O2 release from RBC into medium containing dithionite (40 mmol/l) was measured, by a stopped-flow technique, for nine different species with varying RBC size (man, llama, vicuna, alpaca, dromedary camel, pygmy goat, domestic hen, muscovy duck and turtle). The observed O2 transfer kinetics were found to be size-dependent, i.e. the O2 transfer conductance of the single RBC, gst, was lower, whereas the specific O2 transfer conductance of packed RBC, Gst, or of whole blood, theta st, was higher for smaller RBC. The ratio of surface area to effective diffusion path length which was found to be about one fourth of the mean cell thickness irrespective of cell size and cell shape, may be considered as the essential morphological factor determining O2 transfer efficiency of the single RBC.

Drug release from MCC- and carrageenan-based pellets: experiment and theory.

Microcrystalline cellulose (MCC) is a well-established pelletisation aid. However, MCC pellets generally do not disintegrate, resulting in prolonged drug release, especially in the case of drugs with poor/low aqueous solubility. The major objectives of this study were (i) to modify the prolonged matrix-type drug release from MCC pellets by addition of a disintegrant (croscarmellose Na) or pore former (PEG 6000), (ii) to evaluate carrageenan as potential alternative pelletisation aid for manufacturing high-dose immediate release pellets, and (iii) to better understand the underlying drug release mechanisms. Pellets containing 77-90% drug with poor/low aqueous solubility (vatalanib succinate, SAG/ZK, or theophylline) were prepared by extrusion-spheronisation. All batches showed acceptable yields, aspect ratios, tensile strengths, and porosities. Drug release from MCC pellets was predominantly controlled by pure diffusion and limited drug solubility and could be quantitatively described using Fick's law. Importantly, the apparent drug diffusivity could effectively be adjusted by adding small amounts of a disintegrant or pore former, allowing for release periods ranging from a few minutes to several hours. The drug diffusion coefficients varied between 0.36 and 29 x 10(-6)cm(2)/s. In contrast, carrageenan-based pellets very rapidly disintegrated upon contact with aqueous media and released high doses of drugs with poor/low aqueous solubility within a few minutes.

[Strategies of adaptation of oxygen transport systems in mammals to life at high altitude]. / Strategien der Anpassung des Sauerstofftransportsystems von Säugetieren an das Leben in grossen Höhen.

Like many mammalian species, man responds to exposure to high altitude with an increasing hemoglobin concentration and a decreasing blood O2-affinity. The Lama vicugna of the Andes does not show this kind of adaptation to altitude. Even at high altitude its hematocrit is unusually low and its O2-affinity is the highest known among mammals. Additionally, it is characterized by a high capillary density of the muscles and a large relative heart weight. The consequences of these different strategies of altitude adaptation of the oxygen supply system and the capability for physical performance are discussed.

Effects of hydrophobic and electrostatic cell surface properties of bacteria on feeding rates of heterotrophic nanoflagellates.

The influence of cell surface hydrophobicity and electrostatic charge of bacteria on grazing rates of three common species of interception-feeding nanoflagellates was examined. The hydrophobicity of bacteria isolated from freshwater plankton was assessed by using two different methods (bacterial adhesion to hydrocarbon and hydrophobic interaction chromatography). The electrostatic charge of the cell surface (measured as zeta potential) was analyzed by microelectrophoresis. Bacterial ingestion rates were determined by enumerating bacteria in food vacuoles by immunofluorescence labelling via strain-specific antibodies. Feeding rates varied about twofold for each flagellate species but showed no significant dependence on prey hydrophobicity or surface charge. Further evidence was provided by an experiment involving flagellate grazing on complex bacterial communities in a two-stage continuous culture system. The hydrophobicity values of bacteria that survived protozoan grazing were variable, but the bacteria did not tend to become more hydrophilic. We concluded that variability in bacterial cell hydrophobicity and variability in surface charge do not severely affect uptake rates of suspended bacteria or food selection by interception-feeding flagellates.

Interaction of nutrient limitation and protozoan grazing determines the phenotypic structure of a bacterial community.

We examined the impact of nutrient conditions (carbon and phosphorus limitation) and grazing by protozoans on the phenotypic community structure of freshwater bacteria in continuous culture systems. Lakewater bacteria were grown on mineral medium, which was supplemented with glucose and amino acids and adjusted by different phosphorus concentrations to achieve either carbon or phosphorus limitation. Each nutrient treatment was inoculated with the same bacterial community and consisted of a nongrazing and a grazing treatment, to which the heterotrophic nanoflagellates Spumella sp. and Ochromonas sp. were added. We found that nutrient conditions alone resulted in differences in the phenotypic structure of the bacterial community: small and motile bacteria dominated under C limitation while large, elongated, and capsulated bacteria were characteristic for P limitation. The genotypic community composition as measured by T-RFLP (terminal restriction fragment length polymorphism) was not severely influenced by the two nutrient treatments. In the presence of flagellate predators, grazing-resistant bacteria developed under both nutrient conditions, but with different survival mechanisms: highly motile bacteria prevailed under C limitation, whereas the P-limited grazing treatment was dominated by filamentous forms. T-RFLP analysis revealed only moderate changes in bacterial community composition due to grazing, which were most pronounced under P limitation. Analysis by video microscopy revealed that high swimming speed is an efficient nonmorphological survival mechanism for bacteria to reduce the capture success of the flagellate predator. The rejection of optimal-sized, nonmotile bacteria under P limitation suggests the importance of other nonmorphological, surface-located cell properties. Our results illustrate that the realized mechanisms of grazing resistance are linked to the actual limitation conditions, and that the combined effects of nutrient limitation and grazing are major determinants of bacterial community structure.

[Aniseikonia in unilateral pseudophakia]. / Aniseikonie bei einseitiger Pseudophakie.

The authors report on a study of 20 patients (average age 56 years) with postoperative visual acuity of more than 0.8 in each eye. The patients had all undergone surgery for unilateral cataract with implantation of a posterior chamber lens. The aniseikonia was measured subjectively, and determined objectively by mathematical means. The quality of stereopsis was not influenced by the degree of aniseikonia (the maximum was 12.2%). The power of intraocular lenses for unilateral cataract should be chosen to produce not only slight aniseikonia but also minimal anisometropia.