Frank C. Mooren

Serum S100β increases in marathon runners reflect extracranial release rather than glial damage

The contribution of extracranial tissue damage to serum S100β increases was examined in 18 marathon runners without clinical or laboratory signs of brain damage. Postrace serum S100β and creatine kinase (CK) concentrations increased (p < 0.001), and areas under the curve were highly correlated (p = 0.001). To conclude, serum S100β increases after running originate from extracranial sources. CK determination may improve specificity of S100β as a marker of brain tissue damage in acute trauma.

Calcium–magnesium interactions in pancreatic acinar cells

Although the role of calcium (Ca2+)in the signal transduction and pathobiology of the exo¬crine pancreas is firmly established, the role of magne¬sium (Mg2+) remains unclear. We have characterized the intracellular distribution of Mg2+ in response to hormone stimulation in isolated mouse pancreatic acinar cells and studied the role of Mg2+ in modulating Ca2+ signaling using microspectrofluorometry and dig¬ital imaging of Ca2+‐orMg2+‐sensitive fluorescent dyes as well as Mg2+‐sensitive intracellular microelectrodes. Our results indicate that an increase in intracellular Mg2+ concentrations reduced the cholecystokinin (CCK) ‐induced Ca2+ oscillations by inhibiting the capacitive Ca2+ influx. An intracellular Ca2+ mobiliza¬tion, on the other hand, was paralleled by a decrease in [Mg2+]i, which was reversible upon hormone with¬drawal independent of the electrochemical gradients for Mg2+,Ca2+,Na+, and K+, and not caused by Mg2+ efflux from acinar cells. In an attempt to characterize possible Mg2+ stores that would explain the reversible, hormone‐induced intracellular Mg2+ movements, we ruled out mitochondria or ATP as potential Mg2+ buffers and found that the CCK‐induced [Mg2+]i de¬crease was initiated at the basolateral part of the acinar cells, where most of the endoplasmic reticulum (ER) is located, and progressed from there toward the apical pole of the acinar cells in an antiparallel fashion to Ca2+ waves. These experiments represent the first characterization of intracellular Mg2+ movements in the exocrine pancreas, provide evidence for possible Mg2+ stores in the ER, and indicate that the spatial and temporal distribution of intracellular Mg concentra¬tions profoundly affects acinar cell Ca2+ signaling.— Mooren, F. C., Turi, S., Günzel, D., Schlue, W.‐R., Domschke, W., Singh, J., Lerch, M. M. Calcium‐mag¬nesium interactions in pancreatic acinar cells. FASEB J. 15, 659‐672 (2001)

Exercise affects tissue lymphocyte apoptosis via redox-sensitive and Fas-dependent signaling pathways

Intensive and exhaustive exercise induces an activation of blood T-lymphocytes, which seems to be terminated by apoptotic processes in the postexercise period. Here, we report that exercise-induced T-lymphocyte apoptosis is a systemic phenomenon occurring in various lymphoid and nonlymphoid tissues. The apoptosis rate could be related to exercise intensity and type. Although in some tissues, such as the spleen and Peyers patches, an early start of apoptosis (1-3 h postexercise) could be detected, a delayed apoptosis (24 h postexercise) was observed in lung, bone marrow, and lymph nodes. Further analysis showed a similar apoptosis distribution among lymphocyte subpopulations. We tested whether components of the extrinsic or the intrinsic apoptotic pathways or both were involved in these processes. Elevated levels of lipid peroxidation-product malondialdehyde (MDA), indicating an increased production of reactive oxygen species (ROS), were found after exercise in Peyers patches, lung, and spleen, but not in lymph nodes. Application of N-acetyl-cysteine (NAC) prevented exercise-induced T-cell apoptosis completely in spleen and bone marrow, partially in lung and Peyers patches, while it was ineffective in lymph nodes. Additionally, exercise addressed the Fas-mediated apoptosis. The percentage of Fas-receptor (Fas+) and Fas-ligand positive (FasL+) lymphocytes was enhanced in Peyers patches after exercise. Moreover, FasL+ T cells were increased in the lung, while in lymph nodes Fas+ cells were increased. The critical role of Fas signaling in exercise-induced apoptosis was supported by using Fas-deficient MRL/lpr-mice. In Fas-deficient mice, exercise-induced T-lymphocyte apoptosis was prevented in spleen, lung, bone marrow, and lymph nodes, but not in Peyers patches. These data demonstrate that exercise-induced lymphocyte apoptosis is a transient systemic process with tissue-type specific apoptosis-inducing mechanisms, whose relevance for the adaptive immune competence remains to be shown.

Cellular calcium in health and disease

Sidney Ringer, in 1882, was the first to recognize the relevance of calcium, an element discovered in w x 1908 1 , for cellular function. He discovered the necessity of Ca for heart contraction and described its role during development of fertilized eggs and cell w x adhesion 2–4 . In the late 1920s, it became evident that intracellular Ca is the link between hormonereceptor binding and cellular responses like secretion w x or movement 5–8 . Understanding the biological role of Ca depended on methodological progress. First intracellular measurements of free Ca using w x microinjection and the dye alizarin sulphonate 9 were controversial. An important breakthrough was the introduction of the Ca-sensitive photoprotein w x aequorin by Ridgway and Ashley 10 , and further improvements by metallochromic Ca indicators w x 11 . The still rather limited sensitivity was overcome 2q w x 2q by Ca microelectrodes 12 and by Ca -sensitive w x fluorescent dyes, like indo-1 and fura-2 13,14 .

In Vitro Permeability of PBCA Nanoparticles through Porcine Small Intestine

Peroral nanoparticle-mediated drug absorption was studied using a laser scanning confocal microscope. Additional diffusion studies in side-by-side diffusion cells with radiolabelled polybutylcyanoacrylate (PBCA) nanoparticles were carried out to confirm the results of this study. Fluorescence-labelled PBCA nanoparticles were incubated in vitro in the lumen of freshly excised intestine. Computer-aided optical sectioning of thick samples with dramatically improved resolution and the possibility of rejecting out-of-focus noise enabled tracking of the fluorescence-labelled PBCA nanoparticles in the intestinal tissue after incubation of the particles in freshly excised porcine small intestine. The results of this study suggest that the nanoparticles are absorbed by the surface of the gut wall, creating a high concentration gradient, thereby enhancing the absorption of drugs that may be loaded to the nanoparticles. A significant amount of particles was found in hot (very fluorescent) spots that were assumed to be Peyers patches. No particles, however, traversed the entire gut wall over a period of 2 to 4 h. These results were confirmed by the diffusion study. No radioactivity permeated through Peyers-patch-free intestine within 4 h, whereas the amount of radioactivity that was transported through intestine with Peyers patches during this time was 1.1% of the total amount in the donor chamber.

Intracellular calcium in primary cultures of rat renal inner medullary collecting duct cells during variations of extracellular osmolality

There is ample evidence of calcium being an intracellular second messenger during volume regulatory processes in various cells including inner medullary collecting duct (IMCD) cells. Therefore, we measured intracellular calcium concentrations (Cai under anisotonic conditions in primary cultures of IMCD cells using the Fura-2 technique. Basal steady-state calcium at 600 mosmol/l was found to be 110±4 nmol/l; n=119. Exposure to hypotonic medium (300 mosmol/l, reduction of sucrose) resulted, within 1 min, in a strong increase in calcium to 563±87 nmol/l (n=7; P<0.01), followed by a decrease over 4–6 min to twice the initial values. The calcium increase was smaller (260±14 nmol/l; n=5; P<0.05) when the osmotic pressure was decreased by reducing NaCl instead of sucrose. Stepwise reduction of osmolarity to either 500 or 400 mosmol/l increased calcium by a significantly smaller extent, suggesting a threshold for calcium influx between 400 and 300 mosmol/l. In hypotonic calcium-free solutions no significant increase in calcium was observed. Verapamil (40 μmol/l), D-600 (40 μmol/l), diltiazem (40 μmol/l), and nifedipine (40 μmol/l) inhibited the hypotonically induced calcium influx in decreasing order of potency. Lanthanum (La3+) and gadolinium (Gd3+) had no effect. Membrane depolarization by incubation in potassium-rich solution diminished calcium influx. Preincubation with cytochalasin B (50 μmol/l for 30 min) resulted in a lower basal calcium level and attenuated the calcium increase during hypotonic shock. These results demonstrate an increased calcium influx during hypotonic shock in IMCD cells in culture mediated by channels whose nature (stretch activated and/ or voltage dependent) remains to be determined. The transient increase in Cai in turn may trigger inorganic and organic osmolyte fluxes observed previously.

Intensive resistance exercise induces lymphocyte apoptosis via cortisol and glucocorticoid receptor-dependent pathways

Intensive endurance exercise is known to induce lymphocyte apoptosis, which might affect immune function. Less is known about the effects of resistance exercise on apoptosis and its underlying mechanisms. In this study, subjects performed an intensive resistance test (IRT) and a moderate resistance test, and lymphocyte apoptosis, apoptosis-related parameters, and underlying mechanisms were investigated. IRT induced a significant increase of lymphocyte apoptosis 3 h after exercise, which was accompanied by a significant decrease of mitochondrial membrane potential, a reduction of Bcl-2, and an upregulation of the CD95 receptor. Blood lactate, IL-6, C-reactive protein, and cortisol increased significantly 3 h after IRT. A significant correlation was observed between the increase of apoptosis and cortisol levels 3 h after IRT. Incubation of freshly isolated lymphocytes in IRT serum indicated an important role of serum correlates for apoptosis induction. Selective incubation of lymphocytes in concentrations of selected serum parameters corresponding to levels found post in IRT serum demonstrated a major role for cortisol in apoptosis induction. This result was confirmed by attenutation of apoptosis after addition of mifepristone before incubation in IRT serum. In summary, resistance exercise induced lymphocyte apoptosis in an intensity-dependent way. Furthermore, cortisol signaling via glucocorticoid receptors might be an important mechanism for lymphocyte apoptosis after resistance exercise.

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.

Hypotonicity-Evoked Release of Organic Osmolytes from Distal Renal Cells: Systems, Signals, and Sidedness

After a detailed description of early cellular, membrane and intracellular events in rat renal medullary collecting duct cells when exposed to hypotonicity, a synopsis on organic osmolyte transport properties, possible trigger mechanisms, and the cellular location of transport pathways is given. From the data currently available on renal and nonrenal cells, it is concluded that hypotonicity-evoked efflux of all organic osmolytes appears to be mediated by transport proteins which share a variety of properties more typical for channels than for carriers. A large diversity seems to exist, however, for the signalling mechanisms. Such diversity allows the cells to regulate the intracellular concentration of different organic osmolytes independently of each other, giving flexibility to the spectrum of osmotic responses. The site of release also varies from cell to cell; here conservation of organic osmolytes for future reuptake or further metabolism appears to be the major determinant.

Physical performance profile of handball players is related to playing position and playing class.

Abstract Krüger, K, Pilat, C, Ueckert, K, Frech, T, and Mooren, FC. Physical performance profile of handball players is related to playing position and playing class. J Strength Cond Res 28(1): 117–125, 2014—The purpose of the study was to compare anthropometric data and physical performance characteristics between different playing positions in professional team handball. Furthermore, a comparison between performance profiles of first and second division players was made. Thirty-four male professional handball players were recruited. Measurement of heart rates (HRs) during official games anthropometric data, sprint ability, jumping performance, throwing velocity, and endurance performance were determined and analyzed with respect to playing position. In a further step, additional 31 players from German second division were recruited to compare their profile on each position with profile of the first division players. Players of wings and backs positions had highest average HRs during game, best times in 30-m sprint tests, best jumping performance, and best anaerobic endurance performance. Similarly, backs and wings reached highest throwing velocities. Regarding anthropometric characteristics, wings were players with lowest body height and weight, whereas pivots were heaviest players and players with highest body mass index (BMI). We further found that wings from first division had a better sprint performance compared with wings from second division. Furthermore, pivots from first division had higher BMI and drop jump performance. Our data demonstrated a close relationship of anthropometric data, physical performance characteristic, and the playing position of handball. These information might be helpful for the assessment and evaluation of talents and may help to develop and optimize position-specific training regimes and identification of talents.