Newly developed magnesium alloys for powertrain applications

Several new magnesium alloys have been developed recently for high-temperature applications to obtain an optimal combination of die cast-ability, creep resistance, mechanical properties, corrosion performance, and affordability. Unfortunately, it is difficult to achieve an adequate combination of properties and, in fact, most of the new alloys can only partially meet the required performance and cost. The ZE41 alloy, which is used for most gravity-casting applications, has moderate strength and creep resistance combined with good cast-ability. Although this alloy exhibits poor corrosion resistance, it is still preferred for certain applications. For more information, contact E. Aghion, Dead Sea Magnesium Ltd., P.O. Box 1195, Beer Sheva 84111, Israel; +972-8-628-2422; fax +972-8-628-2431; e-mail eli@dsmag.co.il.     

In Vitro antimicrobial susceptibilities of Streptococcus pneumoniae isolated from two teaching hospitals in Taiwan, 1989-1995

The susceptibility of 46 pneumococcal isolates collected during October 1989 to May 1995 from National Taiwan University Hospital and Taipei Municipal Yang Ming Hospital was studied. Among these isolates, the resistant rate of penicillin G was 21.7%; the penicillin G-resistant strains were more frequently resistant than the penicillin-sensitive strains to other beta-lactam antimicrobial drugs. The minimum bactericidal concentrations (MBCs) of penicillin G for all isolates were equal to, or one dilution higher than, minimum inhibitory concentrations (MICs). Three strains were false positive for penicillin resistance among isolates of Streptococcus pneumoniae screened with oxacillin. On the other hand, resistance to penicillin G was often independent of resistance to erythromycin. Vancomycin was the most active agent tested.     

The effect of alterations to action potential duration on beta-adrenoceptor-mediated aftercontractions in human and guinea-pig ventricular myocytes

Aftercontractions induced by beta-adrenoceptor stimulation in human and guinea-pig cardiomyocytes may be related to changes in action potential duration (APD). We investigated the effects of altering APD during the occurrence of isoproterenol-induced aftercontractions, using the KATP channel openers cromakalim and lemakalim or the action potential voltage clamp technique, in guinea-pig and human ventricular cardiomyocytes. Contractile responses were measured at 32 degrees C using a video-based edge-detection system. In guinea-pig myocytes, action potentials, Indo-1 fluorescence and contraction were measured at 22 degrees C. Isoproterenol (< or = 12 nM) had variable effects on APD but induced aftercontractions, the majority (14/19 cells) of which occurred during the action potential. Short action potentials were produced using K+ channel openers. These compounds reduced or completely abolished the isoproterenol-induced aftercontractions. Increasing isoproterenol in the presence of K+ channel opener restored the main contraction to a level similar to or above those with isoproterenol alone, but without the reappearance of aftercontractions. When cells were stimulated to contract under action potential voltage clamp, isoproterenol-induced aftercontractions were abolished by voltage clamping with action potentials of short duration. It was possible to induce aftercontractions in some cells without application of isoproterenol if voltage clamp-imposed action potentials of very long duration were used. These aftercontractions were also abolished by shortening action potential duration. We conclude that K+ channel openers or the imposition of action potentials of short duration can dissociate positively inotropic beta-adrenoceptor stimulation from aftercontraction formation and that action potentials of long duration can be pro-arrhythmic.     

Interferometric polarization mode dispersion measurements withfemtosecond sensitivity

The standard interferometric measurement technique for polarization mode dispersion (PMD) measures the cross correlation of the electromagnetic field at the output of the fiber or optical device under test when a broadband light source is used. The sensitivity (smallest measurable PMD delay) of this technique is limited by the coherence time of the light source. In this contribution, we critically analyze extensions of the interferometric technique to lower values and present a new extension which provides a sensitivity of a few femtoseconds     

Measurements of Ca2+ entry and sarcoplasmic reticulum Ca2+ content during the cardiac cycle in guinea pig and rat ventricular myocytes

This study investigates the contribution of Ca2+ entry via sarcolemmal (SL) Ca2+ channels to the Ca2+ transient and its relationship with sarcoplasmic reticulum (SR) Ca2+ content during steady-state contraction in guinea pig and rat ventricular myocytes. The action potential clamp technique was used to obtain physiologically relevant changes in membrane potential. A method is shown that allows calculation of Ca2+ entry through the SL Ca2+ channels by measuring Cd(2+)-sensitive current during the whole cardiac cycle. SR Ca2+ content was calculated from caffeine-induced transient inward current. In guinea pig cardiac myocytes stimulated at 0.5 Hz and 0.2 Hz, Ca2+ entry through SL Ca2+ channels during a cardiac cycle was approximately 30% and approximately 50%, respectively, of the SR Ca2+ content. In rat myocytes Ca2+ entry via SL Ca2+ channels at 0.5 Hz was approximately 3.5% of the SR Ca2+ content. In the presence of 500 nM thapsigargin Ca2+ entry via SL Ca2+ channels in guinea pig cardiac cells was 39% greater than in controls, suggesting a larger contribution of this mechanism to the Ca2+ transient when the SR is depleted of Ca2+. These results provide quantitative support to the understanding of the relationship between Ca2+ entry and the SR Ca2+ content and may help to explain differences in the Ca2+ handling observed in different species.     

"Expressed emotion", marital quality and risk of recurrence in depressed patients

BACKGROUND: This study investigated the assignment of preference values to health states which may follow head and neck cancer (HNC) treatment. Preference values for these health states were provided by HNC patients, HNC health-care providers, and a group of college students representing individuals with little knowledge of HNC. METHODS: A time trade-off technique was used by participants to assign preference values to four health states in the domains of appearance, eating, speech, breathing, pain, and work/social functioning. RESULTS: Patients' and health-care professionals' rank-ordered preference value scores for health states in appearance, breathing, eating, and speech were not significantly different (p < .05). These two groups differed significantly in ranking four of the eight pain and work/social functioning health states. Patients and students differed significantly in ranking 21 of the 24 health states (p < .05). CONCLUSIONS: Health-care professionals and patients had very similar perspectives regarding health states in the HNC-specific domains, indicating that these professionals appear to be a legitimate proxy for patients' attitudes in these domains. Healthcare professionals placed a significantly greater value on avoiding both pain and social confinement than did patients. Students, representing individuals naive regarding HNC, differed from patients and health-care professionals in their rankings of these health-state outcomes.     

Proteases and their inhibitors are indicative in gestational disease

OBJECTIVE: To assess whether various proteolytic factors which are involved in trophoblast invasion show different concentrations in plasma and placenta of patients with HELLP syndrome, pre-/eclampsia and highly pathological Doppler flow measurements but without additional complications (hpD). DESIGN: Case control and observational study; 18 women with HELLP syndrome, 21 with pre-/eclampsia, 13 with hpD, as well as healthy pregnant women (matched pairs); statistical analysis: sign test and Wilcoxon test. RESULTS: Urokinase-type plasminogen activator (uPA), uPA receptor, tissue-type plasminogen activator (tPA), plasminogen activator inhibitor 1 (PAI-1), matrix metalloproteinases MMP-8, MMP-9 and tissue inhibitor of metalloproteinases TIMP-1 were measured by ELISA. PAI-1 plasma levels are significantly elevated in all three groups studied. In HELLP syndrome, tPA and TIMP-1 are also elevated, and in patients with hpD, MMP-8 is increased, whereas MMP-9, and TIMP-1 are lower. In placenta extract, only pre-/eclampsia shows reduced MMP-9 concentrations. CONCLUSIONS: The increased frequency of small-for-gestational-age infants observed in all three study groups is an expression of impaired placental implantation and remodelling processes. These disturbances manifest themselves in the form of changes in some of the factors in plasma and placenta extract that are involved in these processes.