Characterization and correlation of mobile phase dispersion of aqueous-organic solvent systems in centrifugal partition chromatography.

To reach a high separation efficiency using Centrifugal Partition Chromatography (CPC), the fluid dynamical behavior of the liquid-liquid two-phase systems must be clearly understood. The fluid dynamics, namely the dispersion, the coalescence, and the stationary phase retention, have a high impact on a separation. Especially the mobile phase dispersion influences the mass transfer during a separation. In this study, the mobile phase dispersion of different aqueous-organic solvent systems was characterized for ascending and descending mode via video analysis. Thereby the influence of the physical properties of the solvent systems, the operating parameters, and the geometry of the chamber inlet was investigated systematically using dimensional analysis. With the help of the dimensionless numbers Ohnesorge number (OhCPC), Eötvös number (EoCPC), and Weber number (WeCPC) the impact of the solvent system, the plant parameters, and the operating parameters on the mobile phase dispersion could be described. Inside the three dimensional area, spanned by the dimensionless numbers, each state of mobile phase dispersion (undispersed, low dispersed, highly dispersed, and atomized) could be allocated to an individual region for both operating modes. Moreover, differences in mobile phase deflection depending on the operating mode and a possible reason for these were described.

Correlating the phase settling behavior of aqueous-organic solvent systems in a centrifugal partition chromatograph.

The prediction of the performance of a Centrifugal Partition Chromatography (CPC) is a difficult but desirable task. The partitioning of the sample, as well as the fluid dynamical phenomena dispersion, coalescence, and stationary phase retention have to be individually understood. Therefore, the phase settling behavior of different aqueous-organic solvent systems and with this, the dependency of the stationary phase retention in CPC was investigated in this study. On the one hand, batch settling experiments were performed, and the settling velocity of aqueous-organic solvent systems was investigated. With this it was possible to correlate the stationary phase retention in CPC in both operating modes. For descending mode operation a high settling velocity of the lower phase and for ascending mode a high settling velocity of the upper phase is needed for a stable operation and a high stationary phase retention. On the other hand, the dimensionless numbers Capillary number (Ca) and Morton number (Mo) were used to generate a universally applicable correlation for the stationary phase retention in ascending mode. It was shown, that a high stationary phase retention correlates with low values of Ca and Mo, whereas the influence of Mo is neglectable in the parameter space investigated. Within this correlation, the individual influence of each influencing parameter on the stationary phase retention was included. Moreover, this correlation was compared to descriptions for descending mode given in literature. With this it was shown that the minimal stationary phase retention is correlatable to the point of phase inversion.

Correlating physical properties of aqueous-organic solvent systems and stationary phase retention in a centrifugal partition chromatograph in descending mode.

The performance of the Centrifugal Partition Chromatography (CPC) as a liquid-liquid chromatographic technique depends strongly on the two-phase solvent system used. Thereby the individual influence of the retention of the stationary phase, the coalescence, and the dispersion of the mobile phase in the chambers must be understood to select appropriate solvent systems and reach high separation efficiencies. In this study, an optical measurement system was used to investigate the influence of the physical properties of the Arizona solvent systems on the stationary phase retention in descending mode. Therefore, physical properties like density, viscosity, and interfacial tension were measured as well as the stationary phase retention. Using dimensionless numbers, a correlation between the stationary phase retention and the influencing parameters could be determined. The correlation was validated using data from the literature. Additionally, the solvent systems were modified by additives to identify the validity of the correlation. It was proven that the dimensionless numbers Capillary number (Ca) and Morton number (Mo) can be used to predict the stationary phase retention of other liquid-liquid solvent systems as well as for different operating conditions.

Intrinsic network connectivity reflects consistency of synesthetic experiences.

Studying cognitive processes underlying synesthesia, a condition in which stimulation of one sensory modality automatically leads to abnormal additional sensory perception, allows insights into the neural mechanisms of normal and abnormal cross-modal sensory processing. Consistent with the notion that synesthesia results from hyperconnectivity, functional connectivity analysis (adopting independent component analysis and seed-based correlation analysis) of resting-state functional magnetic resonance imaging data of 12 grapheme-color synesthetes and 12 nonsynesthetic control subjects revealed, in addition to increased intranetwork connectivity, both a global and a specific (medial and lateral visual networks to a right frontoparietal network) increase of intrinsic internetwork connectivity in grapheme-color synesthesia. Moreover, this increased intrinsic network connectivity reflected the strength of synesthetic experiences. These findings constitute the first direct evidence of increased functional network connectivity in synesthesia. In addition to this significant contribution to the understanding of the neural mechanisms of synesthesia, our results have important general implications. In combination with data derived from clinical populations, our data strongly suggest that altered differences in intrinsic network connectivity are directly related to the phenomenology of human experiences.

Participation in sports and physical activity of haemophilia patients.

Modern therapy options offer haemophiliacs more and more possibilities for an active participation in sports. The purpose of the present study was to investigate the attitude of these patients towards sports, their participation in school and leisure time sports activities, and differences between juveniles and adults. We investigated 44 children and adolescents (aged from 4 to 16 years) and 27 adults (aged from 18 to 72 years) with haemophilia by means of a questionnaire. 79.6% of the juvenile patients participated always or almost always in school sports, while this percentage was significantly (P < 0.05) lower in the former school time of the adults (37%). Sports play an important or very important role in leisure time activities for 75% of the adolescent and 55.5% of the adult haemophiliacs (P < 0.05). Bleeding complications occurred in 17.6% of all patients; there was no correlation with any particular type of sports. There were only slight differences between both groups, regarding their motivation to participate in sports activities. The main reasons involved social aspects and having fun. The results show that the modern therapy of haemophilia probably leads to a more positive attitude towards sports and to a wider spectrum of practised sports. This, however, may be associated with an increasing potential of health risks, which require a high level of sports medical care.

Resistance in introduced populations of a freshwater snail to native range parasites.

Introduced species provide an opportunity to examine responses to novel ecological conditions, in particular to the absence of co-evolved enemies. Introduced populations could evolve lower investment in resistance or could down-regulate their immune system as a plastic response to enemy absence. The response might have consequences for the success of introduced species. Assuming a trade-off between resistance and traits related to demographic success, an evolved change or reallocation from resistance could increase the chances of invasions. On the other hand, introduced populations could have increased resistance as a correlate of greater vigour and competitive ability among successful invaders [Sampling Bias hypothesis (SBH)]. These hypotheses make different predictions about investment in resistance in introduced populations. Using a New Zealand clonal snail (Potamopyrgus antipodarum), we examined the resistance of three introduced genotypes (one from the US and two from Europe) to several populations of a native range parasite (Microphallus sp.). One genotype (Euro A) was resistant to all native range parasite populations, consistent with the SBH. However, two remaining genotypes (Euro C and US 1) were less susceptible to parasite populations that were allopatric to their source populations. Furthermore, resistance of one genotype (US 1) collected from the introduced range was indistinguishable from its resistance when collected from the range of the parasite. Hence, there was no evidence for decreased resistance in the absence of native enemies, which is inconsistent with hypotheses that envision reduced allocation to resistance or a trade-off between competitive ability and resistance.

Serum S100beta increases in marathon runners reflect extracranial release rather than glial damage.

The contribution of extracranial tissue damage to serum S100beta increases was examined in 18 marathon runners without clinical or laboratory signs of brain damage. Postrace serum S100beta and creatine kinase (CK) concentrations increased (p < 0.001), and areas under the curve were highly correlated (p = 0.001). To conclude, serum S100beta increases after running originate from extracranial sources. CK determination may improve specificity of S100beta as a marker of brain tissue damage in acute trauma.

Creatine loading and resting skeletal muscle phosphocreatine flux: a saturation-transfer NMR study.

31P saturation-transfer nuclear magnetic resonance spectroscopy was used to study skeletal muscle phosphocreatine (PCr) flux in healthy male volunteers. Data analysis included consideration of effects from incomplete saturation and radiofrequency spillover. Spectra were recorded from the resting gastrocnemius muscle before and after 6 days of creatine monohydrate (Cr-H2O) intake (20 g/day). Parallel to an improved muscle performance during maximal intermittent exercise following Cr-H2O supplementation, the concentration of PCr increased (P=0.01) by 23% (34.9+/-2.8 mmol/l vs. 28.6+/-2.7 mmol/l), whereas other metabolites were unaffected (inorganic phosphate: 4.3+/-1.4 mmol/l, free intracellular Mg(2+): 1.1+/-0.7 mmol/l, cytosolic pH: 7.04+/-0.02). Forward and reverse fluxes through the creatine kinase (CK) reaction did not change significantly from their baseline levels (v(for): 11.8+/-5.4 mmol/l per second vs. 15.3+/-6.8 mmol/l per second, (v(rev): 9.5+/-3.4 mmol/l per second vs. 10.9+/-3.7 mmol/l per second). The rate of PCr resynthesis in resting muscle is not limited by the CK reaction, which is near equilibrium. Consequently, the post-load increase in total creatine has no effect on the unidirectional CK reaction rates.

Decoupling of intracellular calcium signaling in granulocytes after exhaustive exercise.

There is growing evidence that exhaustive exercise can induce a suppression of the innate immune functions. Most studies so far describe exercise induced changes in cell counts or functional responses while information regarding intracellular signal transduction parameters is lacking. Therefore in the present study we investigated in granulocytes the regulation of intracellular calcium ([Ca2+]i) which is an important intracellular second messenger. Healthy volunteers underwent a treadmill exercise test at 80% of their maximal oxygen uptake until exhaustion. Granulocytes were separated before and 1 hour after the test. [Ca2+]i was analyzed spectrophotometrically using the Ca2+ sensitive fluorescent dye Fura-2, while the oxidative burst and phagocytosis were measured by flow cytometry. While resting [Ca2+]i levels were unchanged, the Ca2+ transient induced N-formyl-methionyl-leucyl phenylalanine (fMLP) and platelet activating factor (PAF) were enhanced 1 hour after the test compared to pre-exercise values although fMLP receptor density did not change. In contrast, oxidative burst and phagocytosis evoked by fMLP and phorbol-myristate-acetate (PMA) were decreased after exercise. Together, our data support the view that exhaustive exercise affects regulation of Ca2+ signaling in granulocytes. The potentiation of Ca2+ signals is not accompanied by an enhancement of cellular functional parameters suggesting a blockade in intracellular signalling pathways.

Alterations in intracellular calcium signaling of lymphocytes after exhaustive exercise.

PURPOSE: Exhaustive exercise is accompanied by pronounced quantitative changes in leukocytes. Whereas most studies on lymphocytes have concentrated on their proliferative responses or cytokine secretion, not much is known about exercise-induced changes in intracellular signal transduction processes. In lymphocytes, the concentration of intracellular free calcium ([Ca(2+)](i)) is an important intracellular second messenger linking extracellular stimuli to cellular responses. The aim of the present study was to examine the effect of exhaustive exercise on the calcium homeostasis of lymphocytes. METHODS: Healthy volunteers underwent treadmill exercise at 80% of their maximal oxygen uptake until exhaustion. Blood samples were taken before, immediately after, 1 h after, and 1 d after the test. Lymphocyte subsets were analyzed by flow cytometry; isolation of lymphocytes was performed by density gradient centrifugation. [Ca(2+)](i) was measured using the calcium-sensitive fluorescent dye Fura-2. RESULTS: Compared with preexercise conditions, basal [Ca(2+)](i) was increased immediately after exercise, whereas there was no change after 1 h or 1 d. The anti-CD3- and phytohemagglutinin-induced Ca(2+) responses demonstrated a bivalent pattern. Immediately after exercise, Ca(2+) transients were impaired, whereas 1 h after and 1 d after the test, the Ca(2+) responses were increased. In contrast, the Ca(2+) responses induced by thapsigargin were not different at any time interval. Lymphocyte subsets increased immediately after exercise, especially natural killer cells and CD8+ T cells, and decreased below preexercise levels after 1 h. One day after exercise, cell counts were not different from preexercise levels. CONCLUSIONS: Taken together, this novel approach demonstrates that exhaustive exercise has a profound influence on intracellular calcium signaling of lymphocytes. These effects may explain changes in lymphocyte function that have previously been reported.

[Pronation angle of the rear foot during running in relation to load]. / Pronationswinkel des Rückfusses beim Laufen in Abhängigkeit von der Belastung.

In 20 volunteers the relationship between rear-foot pronation and increasing physical exertion during treadmill ergometry was examined. In order to assess the influence of regularly performed running training a group of 10 endurance trained middle- and long-distance runners (age: 27.4 +/- 4.9 years; weight: 71.0 +/- 8.8 kg; height: 184.2 +/- 8.3 cm) was compared to another group of 10 untrained subjects (age: 24.7 +/- 2.1 years; weight: 73.3 +/- 9.8 kg; height: 179.1 +/- 8.3 cm). The examinations were carried out on a treadmill using a high-frequency motion analyzing system. Heart rate, blood lactate as well as rear-foot pronation were measured. Regarding heart rate and lactate concentration there were significant differences between trained and untrained volunteers. The pronation angle increased with higher speed up to a maximum of 6.54 +/- 4.22 degree for the trained group and 6.84 +/- 4.59 degree for the untrained group. With reference to maximal as well as submaximal stages the pronation angles showed no significant differences between both groups. Following the maximal exercise level the runners performed an additional 3 min run with a velocity reduced by 8 km/h compared to the maximal speed. At this level the total group as well as the untrained group showed significantly greater pronation angles compared to those of the corresponding velocity at the beginning of the test. The extent of the differences, however, was not significantly correlated with the lactate levels. Our results demonstrate that the increase of the pronation angle is a function of the running speed. But there is also an influence of fatigue, which depends neither on the running velocity nor on the lactate levels during exercise. Therefore, further investigations should emphasize the question which factors are responsible for this effect.

Release of glucagon-like peptide-1 (GLP-1) by carbohydrates in the perfused rat ileum.

The effect of various carbohydrates on glucagon-like peptide-1 (GLP-1) release was studied in the in vivo perfused rat ileum. GLP-1 concentrations in the mesenteric venous effluent increased significantly after luminal perfusion with substrates of a sodium/glucose co-transporter (D-glucose, D-galactose, methyl-alpha D-glucoside, and 3-O-methyl-D-glucose). D-Fructose induced a sodium-independent release of GLP-1. Carbohydrates like 2-deoxy-D-glucose and N-acetyl-D-glucosamine, which are not substrates of a luminal sodium/glucose or fructose transporter, did not affect GLP-1 release. Since methyl-alpha D-glucoside is not a substrate of the basolateral glucose transport mechanism and 3-O-methyl-D-glucose is not metabolized within intestinal cells, it is concluded that intracellular metabolism of carbohydrates and intracellular removal are not essential to induce GLP-1 secretion in rats.

[Is the orthopedically correct lifting technique rational from a cardiopulmonary and metabolic viewpoint?]. / Ist die "orthopädisch" richtige Hebetechnik aus kardiopulmonaler und metabolischer Sicht sinnvoll?

INTRODUCTION: In spite of educational work for many years by the orthopaedic surgeons wrong lifting techniques are still used in everyday life as well as during exercise. The reason for this could be the fact that there is an advantage regarding these techniques from the energetic point of view. MATERIAL AND METHODS: To clarify this issue we examined 30 healthy males within the age range of 17 and 30 years (weight: 74.0 +/- 9.2 kg, height: 182.5 +/- 6.7 cm). In a randomised sequence the volunteers carried out two different lifting techniques: 1. Lifting with stretched legs and bent back, 2. Lifting with bent legs and stretched back (Brügger technique). The test scheme consisted of four different 3-minute exercise levels with increasing weights (0 kg, 5.2 kg, 12.1 kg, 19.2 kg), the repetition rate was 30 times per level. RESULTS: Using the Brügger technique the results for heart rate, VO2, VCO2 and VE were highly significant (p < 0.001) above the results of the other technique at all exercise levels. On the RPE (rate of perceived exertion) scale the differences were statistically significant regarding the 0.01-level. CONCLUSION: The results give rise to the supposition that the energy consumption for the lifting technique with the bent back is lower and is therefore preferred in everyday life and during exercise. These findings should be taken into consideration when informing people about possible damages.