Maximum striking velocities in strikes with steel rods-the influence of rod length, rod mass and volunteer parameters.

In blunt force trauma to the head caused by attacks with blunt instruments, contact forces can be estimated based on the conservation of momentum if impact velocities are known. The aims of this work were to measure maximum striking velocities and to examine the influence of rod parameters such as rod mass and length as well as volunteer parameters such as sex, age, body height, body mass, body mass index and the average amount of physical exercise. Steel rods with masses of 500, 1000 and 1500 g as well as lengths of 40, 65 and 90 cm were exemplarily tested as blunt instruments. Twenty-nine men and 22 women participated in this study. Each volunteer performed several vertical strikes with the steel rods onto a passive immobile target. Maximum striking velocities were measured by means of a Qualisys motion capture system using high-speed cameras and infrared light. Male volunteers achieved maximum striking velocities between 14.0 and 35.5 m/s whereas female volunteers achieved values between 10.4 and 28.3 m/s. Results show that maximum striking velocities increased with smaller rod masses and less consistently with higher rod lengths. Statistically significant influences were found in the volunteers' sex and average amount of physical exercise.

Influence of striking technique on maximum striking velocities-experimental and statistical investigation.

Forensic experts often have to assess injury and fatality risks in the context of violent blunt force trauma. Maximum striking velocities in one- and two-handed strikes with a rod-like implement can be of particular interest. Current literature lacks studies addressing this problem. The purpose of this study was therefore to measure and analyse maximum striking velocities in one-handed and two-handed strikes in female and male volunteers. We hypothesised higher striking velocities in two-handed strikes compared to one-handed strikes. Fifty volunteers performed one- and two-handed strikes from top to bottom using a steel rod of 65 cm length and 1000 g weight. A Qualisys™ Motion Analysis system registered displacements of reflecting markers fixed to the rod as well as to the volunteer's body. In one-handed strikes, the mean maximum striking velocity was 17.2 m/s in the female sample and 23.9 m/s in the male sample. Statistically not significantly different maximum striking velocities were found in two-handed strikes with mean values of 18.3 m/s in the female sample and 24.2 m/s in the male sample. Female and male volunteers also yielded similar mean maximum striking velocities in two-handed strikes comparing 'overhead' and 'overshoulder' striking techniques. In conclusion, the striking technique did not relevantly influence maximum striking velocities in our setup.

Bioimpedance-based identification of malnutrition using fuzzy logic.

Protein-energy malnutrition reduces the quality of life, lengthens the time in hospital and dramatically increases mortality. Currently there is no simple and objective method available for assessing nutritional status and identifying malnutrition. The aim of this work is to develop a novel assistance system that supports the physician in the assessment of the nutritional status. Therefore, three subject groups were investigated: the first group consisted of 688 healthy subjects. Two additional groups consisted of 707 patients: 94 patients with primary diseases that are known to cause malnutrition, and 613 patients from a hospital admission screening. In all subjects bioimpedance spectroscopy measurements were performed, and the body composition was calculated. Additionally, in all patients the nutritional status was assessed by the subjective global assessment score. These data are used for the development and validation of the assistance system. The basic idea of the system is that nutritional status is reflected by body composition. Hence, features of the nutritional status, based on the body composition, are determined and compared with reference ranges, derived from healthy subjects' data. The differences are evaluated by a fuzzy logic system or a decision tree in order to identify malnourished patients. The novel assistance system allows the identification of malnourished patients, and it can be applied for screening and monitoring of the nutritional status of hospital patients.

Inhibition of volume-activated chloride currents in endothelial cells by chromones.

1. We have studied the effects of the reported chloride channel blocker, sodium cromoglycate, on volume-activated Cl- currents in endothelial cells from bovine pulmonary artery by means of the whole-cell patch clamp technique. Cl- currents were activated by challenging the cells with a hypotonic extracellular solution of 60% of the normal osmolarity. 2. Half maximal activation of the current at +95 mV occurred after exposure of the cells for 148 +/- 10 s (n = 6) to hypotonic solution (HTS). At the same membrane potential but in the presence of 100 microM sodium cromoglycate (disodium-1,3-bis (2'-carboxylate-chromone-5'-yloxy)-2-hydroxy-propane) activation was delayed (253 +/- 25 s, n = 6) and the maximal current amplitude was reduced to 63 +/- 7% of the control (n = 13). 3. In comparison, an equimolar concentration of NPPB (5-nitro-2(3-phenyl) propylamino-benzoic acid), another Cl- channel blocker, completely blocked the volume-activated current in less than 20 s. 4. Sodium cromoglycate, applied at the time when the HTS-induced current was completely activated, dose-dependently inhibited this current with a concentration for half maximal inhibition of 310 +/- 70 microM. Data for nedocromil sodium were not significantly different from those for sodium cromoglycate. 5. Sodium cromoglycate, loaded into the endothelial cells via the patch pipette in ruptured patches, resulted in a decline of the HTS activated current with a time course that was compatible with diffusion of the compound from the pipette into the cell. Intracellulary applied sodium cromoglycate was also more effective and at 50 microM caused a decrease in the amplitude of the current to 25 +/- 6% (n = 10) of the control current.6 It is concluded that blockade of volume-activated Cl- currents by extracellular sodium cromoglycatemay be due to an intracellular action following its permeation across the cell membrane.

Ca2+ release and activation of K+ and Cl- currents by extracellular ATP in distal nephron epithelial cells.

We have measured ionic currents and changes in intracellular Ca2+ concentration ([Ca2+]i) induced by extracellular ATP in single epithelial cells of the distal nephron from toad (A6 cells). ATP increased [Ca2+]i and concomitantly activated ionic currents. The ATP concentration for half-maximal increase in [Ca2+]i was approximately 10 microM. Current activation and elevation of [Ca2+]i also occurred in Ca(2+)-free bath solutions but were abolished by loading the cells via the patch pipette with 10 mM 1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid (BAPTA) or by preincubating the cells with 10 microM BAPTA-acetoxymethyl ester for 120 min. ATP-activated currents reversed at -53.9 +/- 1.9 mV (n = 22). Tetraethylammonium (TEA, 25 mM), a K+ channel blocker, partially blocked this current but did not affect the Ca2+ transients. The TEA-insensitive component of the current reversed close to Cl- equilibrium potential. 5-Nitro-2-(3-phenylpropylamino) benzoic acid, a putative Cl- channel blocker (100 microM), abolished nearly completely the ATP-activated current. Suramin (100 microM), a P2-purinergic receptor antagonist, strongly attenuated both Ca2+ transients and currents. In cell-attached patches, single channel currents activated by ATP could be observed, i.e., an inwardly rectifying K+ channel with a slope conductance for inward currents of approximately 32 pS and an ohmic Cl- channel with a conductance of 34 pS. It is concluded that ATP activates both Cl- and K+ channels in distal nephron epithelial cells by a Ca(2+)-dependent mechanism.

Activation of the volume-sensitive chloride current in vascular endothelial cells requires a permissive intracellular Ca2+ concentration.

Combined patch clamp and Ca2+-measurements (Fura-2) were used to study the dependence of volume-activated Cl--currents (ICl,vol) of endothelial cells from bovine pulmonary artery on the intracellular Ca2+-concentration [Ca2+]i. Loading the cells with high concentrations of EGTA or BAPTA via ruptured membrane patches or by preincubating them with 50 microM BAPTA-AM caused a substantial decrease of ICl,vol. This reduction was independent of the activation state of the current: the current amplitude was not only diminished if [Ca2+]i was lowered at the peak of the volume-activated current, but this low Ca2+-concentration also prevented activation of the current by a second hypotonic challenge.ICl,vol is already maximally activated at intracellular Ca2+-concentrations between 50 and 100 nmol/l, a further increase of [Ca2+]i does not affect the size of ICl,vol.These results indicate that a sustained full activation of ICl,vol in endothelial cells requires submicromolar concentrations of Ca2+, and that changes in [Ca2+]i do not modulate the current.

Multiple types of chloride channels in bovine pulmonary artery endothelial cells.

We have characterized two different types of Cl- currents in calf pulmonary artery endothelial (CPAE) cells by using a combined patch-clamp and Fura-2 microfluorescence technique to measure simultaneously ionic currents and the intracellular Ca2+ concentration, [Ca2+]i. Exposure of CPAE cells to 28% hypotonic solution induces cell swelling without a change in membrane capacitance and [Ca2+]i, and concomitantly activates a current. This current, I(Cl, vol), is closely correlated with the changes in cell volume and shows a modest outward rectification. It slowly inactivates at potentials more positive than +60 mV but is time- and voltage-independent at other potentials. Increase in [Ca2+]i by different maneuvers, such as application of vasoactive agonists (ATP), ionomycin, or loading of the cells directly with Ca2+ also activates a Cl- current, I(Cl, Ca). This current slowly activates at positive potentials, inactivates quickly at negative potentials and shows strong outward rectification. A time-independent component of the current activated by elevation of [Ca2+]i alone can be inhibited by cell shrinking by exposing the cells to hypertonic solution, indicating that an increase in [Ca2+]i also co-activates I(Cl, vol). Forskolin or cAMP never activated a current in CPAE cells, which indicates the lack of cAMP-activated channels in these cells. There is also no evidence for the existence of voltage-gated Cl- channels in resting, nonstimulated cells. Challenging a cell with elevated [Ca2+]i and hypotonic solutions activated I(Cl, vol) on top of I(Cl, Ca), suggesting that I(Cl, Ca) and I(Cl, vol) are different channels. We conclude that CPAE cells do not express voltage-gated (ClC-type) or cAMP-gated (CFTR-type) Cl- channels, but activate large Cl- currents after volume (mechanical?) or chemical (Ca2+) stimulation.

Annexin II modulates volume-activated chloride currents in vascular endothelial cells.

The membrane-associated, microfilament-binding protein annexin II is abundantly expressed in endothelial cells from calf pulmonary artery (CPAE cells). We have analyzed its role in the regulation of volume-activated chloride currents (ICl, vol) by loading the cells via the patch pipette with a peptide comprising the N-terminal 14 residues of annexin II. This sequence harbors the binding site for the intracellular annexin II ligand, p11, and the peptide interferes with the annexin II-p11 complex formation. Loading of a CPAE cell with this peptide caused a gradual decrease in the amplitude of ICl, vol during repetitive stimulations with a 28% hypotonic extracellular solution. This run down of the current was virtually absent in untreated cells and in cells that were loaded with a mutated 14-amino acid peptide, which has a single amino acid replacement known to result in a more than 1000 times reduced affinity for binding to p11. We conclude that annexin II-p11 complex formation is either directly or indirectly involved in the activation of ICl, vol in endothelial cells.

The volume-activated chloride current in endothelial cells from bovine pulmonary artery is not modulated by phosphorylation.

We employed the patch-clamp technique to investigate the effects of various phosphorylation pathways on activation and modulation of volume-activated Cl- currents (ICl,vol) in cultured endothelial cells from bovine pulmonary arteries (CPAE cells). Half-maximal activation of ICl,vol occurred at a hypotonicity of 27.5+/-1.2%. Run-down of the current upon repetitive activation was less than 15% within 60 min. Stimulation of protein kinase C (PKC) by phorbol-12-myristate-13-acetate (PMA) or by (-)-indolactam did not affect ICl,vol. Down regulation of PKC activity by a 24-h preincubation of the cells with 0.2 micromol/l PMA, or its inhibition by loading the cells with the specific inhibitory 19-31 pseudosubstrate peptide, did not influence ICl,vol. Trifluoperazine and tamoxifen fully blocked ICl,vol with concentrations required for half-maximal inhibition of 3.0 and 2.4 micromol/l respectively. This inhibitory effect is probably not mediated by the calmodulin-antagonistic action of these compounds, because it occurs at free intracellular [Ca2+] of 50 nmol/l, which are below the threshold for calmodulin activation. The tyrosine kinase inhibitor herbimycin A (1 micromol/l) and genistein (100 micromol/l) did not affect ICl,vol. Exposing CPAE cells to lysophosphatidic acid (1 micromol/l), an activator of p42 MAPkinase and the focal adhesion kinase p125(FAK) in endothelial cells, neither evoked a Cl- current nor affected ICl,vol. Neither wortmannin (10 micromol/l), an inhibitor of MAP kinases and of PI-3 kinase, nor rapamycin (0.1 mmol/l), which interferes with the p70S6 kinase pathway, affected ICl,vol. Exposure of CPAE cells to heat or Na-arsenite, both activators of a recently discovered stress-activated tyrosine phosphorylation pathway, neither activated a current nor affected the hypotonic solution-induced Cl- current. We conclude that none of the studied phosphorylation pathways is essential for the activation of the Cl- current induced by hypotonicity.