ATP-activated chloride permeability in biliary epithelial cells is regulated by calmodulin-dependent protein kinase II

Previous studies in freshly isolated rat biliary epithelial cells and in the human cholangiocarcinoma cell line Mz-ChA-1 have demonstrated that ATP activates a calcium-dependent chloride conductance. The coupling between the rise in intracellular calcium and activation of chloride channels has not previously been investigated. In the present study, we evaluated the potential role of calmodulin-dependent protein kinase II (CaMKII) in ATP-activated chloride permeability in Mz-ChA-1 cells. ATP stimulated [125I] efflux, a marker for Cl- movement. Peak efflux rates were inhibited by approximately 60% in cells pretreated with the calmodulin antagonist, W-7. In whole-cell patch clamp recordings, ATP and ionomycin activated calcium-dependent Cl- currents. Pretreatment of cells with the CaMKII inhibitor KN-62 blocked activation by either agent. It is concluded that calcium-dependent activation of chloride currents in Mz-ChA-1 cells is coupled to a CaMKII-dependent process.     

Delayed rupture of the mitral valve complicating blunt chest trauma

A case of anatomical anomaly of the iris's major arterial circle simulating an angioma was discovered in the right eye of a 64-year-old asymptomatic woman during routine ocular examination. We report its clinical and gonioangioiridographic findings.     

Molecular dynamics simulation of boundary lubricated interfaces

A molecular dynamics simulation study of friction in boundary lubrication was conducted in order to investigate the atomic-scale behavior of lubricant molecules during sliding motion. The simulated system consisted of two silicon (001) semi-infinite substrates lubricated by a three-layer film of dodecane. Silicon was modeled using the Stillinger–Weber potential, and the dodecane with the Consistent Force Field function; a novel scheme was used to generate the silicon–dodecane interaction potentials. The simulations show that dodecane molecules strongly prefer to adsorb into the ledges on the silicon surface. The orientation of the adsorbed molecules depends, however, on the concentration of the lubricant at the surface, showing a tendency to stand up at high lubricant concentrations. In sliding, the dodecane layers adsorbed on the surfaces behave as a solid, whereas the middle layer exhibits liquid-like characteristics. The friction coefficient of this well-lubricated case was calculated to be 0.08.     

Oesophageal function in patiensts with angina (author's transl)

Oesophageal functions were measured in 18 patients with angina, 13 healthy volunteers and 29 age-matched patients with reflux disease. Acid clearance was as abnormal in angina patients (88 +/- 46 swallows) as in those with reflux disease (97 +/- 45). The pressure in the lower oesophageal sphincter was low in patients with angina (13 +/- 8 mm Hg). The incidence of hiatal hernia, subjective symptoms during acidification of the oesophagus and results of the reflux provocation test were similar in patients with angina pectoris and healthy controls.     

Hereditary deficiency in complement C7 and platelet aggregation disorders associated with rheumatoid arthritis. One case (author's transl)

In a patient suffering from rheumatoid arthritis thorough investigations led to the discovery of complete deficiency in the 7th component of the complement. A study of the patient's family tree confirmed the hereditary, codominant autosomal character of the deficiency, unrelated to the HLA system. The complement-dependent serum functions were investigated: the opsonizing and chemotactic activities were preserved, but bactericidal properties were lacking. Coagulation studies showed disorders in platelet aggregation in the presence of thrombin, and these were corrected by the addition of C7. The association of a dysimmune disease with C7 deficiency is probably not fortuitous; it might result from a common gene abnormality or, in some cases, from repeated infections.     

The power conversion efficiency of the gold-rhodamine B-bold photoelectrochemical cell

The power conversion efficiency of the photoelectrochemical cell Au---Rhodamine B---Au was found to be (2.4 ± 0.2) × 10⁻⁶ per cent under typical operating conditions. A ten-fold improvement could be expected from constructional modifications, but further increases in efficiency would require changes in the cell chemistry. The low power conversion efficiency can be related to a low (4.7 × 10⁻² per cent) efficiency for the production of the open circuit photovoltage; a low (2.2 × 10⁻² per cent) quantum efficiency for the production of the short circuit current; and to markedly non-rectangular voltage-current characteristics. The deviations from a rectangular relationship and the low efficiency of current production arise from mass-transport limitations rather than from ohmic losses or activation polarisation. The low voltage efficiency probably arises from inefficiencies in the photochemical and electron transfer steps which lead to photovoltage production. The limitations of this type of cell as a solar energy conversion device are discussed.     

Distribution of calcium differs in relaxed and contracted myocardial cells of the rat

Myocardial cells from left ventricles of beating hearts of rats were fixed by immersion in an osmium tetroxide solution containing potassium pyroantimonate to study the electron-microscopic distribution of calcium, the cation being precipitated as an electron-opaque salt (calcium antimonate) by this cytochemical technique. The observed myocytes could be divided into two groups according to their contractile state, evaluated by sarcomere length measurements. In contracted cells (mean sarcomere length 1.43 microgram) the intramyofibrillar precipitate was confined to areas of I-bands bordering the A-bands, the intermyofibrillar space showing scarce content in reaction product. Relaxed cells (mean sarcomere length 1.69 microgram) presented a heavy deposition of reaction product over the sarcomeres, the electron-opaque dots being absent on the H and Z bands. The sarcotubular system and mitochondria were also clearly marked by the reaction product. This second pattern of calcium distribution has not been previously described in heart muscle cells and is interpreted as corresponding to the phase of rise of intracellular calcium which is mediated by membrane depolarization. Our results suggests that different bands of heart sarcomeres show different abilities to bind calcium. The I bands retain the cation even in cells under sustained contraction, probably due to their content in calmodulin; Z and M bands are apparently not involved in calcium sequestration, whereas the content in calcium of the A bands seems to be dependent on the contraction-relaxation cycle of heart myocytes.