Feedback via Ca��⁺-activated ion channels modulates endothelin 1 signaling in retinal arteriolar smooth muscle

PURPOSE: To investigate the role of feedback by Ca��?-sensitive plasma-membrane ion channels in endothelin 1 (Et1) signaling in vitro and in vivo. Methods. Et1 responses were imaged from Fluo-4-loaded smooth muscle in isolated segments of rat retinal arteriole using two-dimensional (2-D) confocal laser microscopy. Vasoconstrictor responses to intravitreal injections of Et1 were recorded in the absence and presence of appropriate ion channel blockers using fluorescein angiograms imaged using a confocal scanning laser ophthalmoscope. Results. Et1 (10 nM) increased both basal [Ca��?](i) and the amplitude and frequency of Ca��?-waves in retinal arterioles. The Ca��?-activated Cl?-channel blockers DIDS and 9-anthracene carboxylic acid (9AC) blocked Et1-induced increases in wave frequency, and 9AC also inhibited the increase in amplitude. Iberiotoxin, an inhibitor of large conductance (BK) Ca��?-activated K?-channels, increased wave amplitude in the presence of Et1 but had no effect on frequency. None of these drugs affected basal [Ca��?](i). The voltage-operated Ca��?-channel inhibitor nimodipine inhibited wave frequency and amplitude and also lowered basal [Ca��?](i) in the presence of Et1. Intravitreal injection of Et1 caused retinal arteriolar vasoconstriction. This was inhibited by DIDS but not by iberiotoxin or penitrem A, another BK-channel inhibitor. Conclusions. Et1 evokes increases in the frequency of arteriolar Ca��?-waves in vitro, resulting in vasoconstriction in vivo. These responses, initiated by release of stored Ca��?, also require positive feedback via Ca��?-activated Cl?-channels and L-type Ca��?-channels.

Simultaneous optical and X-ray observations of flares and rotational modulation on the RS CVn binary HR 1099 (V711 Tau) from the MUSICOS 1998 campaign

We present simultaneous and continuous observations of the Halpha, Hbeta, He I D-3, Na I D-1,D-2 doublet and the Ca II H&K lines for the RS CVn system HR 1099. The spectroscopic observations were obtained during the MUSICOS 1998 campaign involving several observatories and instruments, both echelle and long-slit spectrographs. During this campaign, HR 1099 was observed almost continuously for more than 8 orbits of 2.(d)8. Two large optical flares were observed, both showing an increase in the emission of Halpha, Ca II H K, Hbeta and He I D-3 and a strong filling-in of the Na I D-1, D-2 doublet. Contemporary photometric observations were carried out with the robotic telescopes APT-80 of Catania and Phoenix-25 of Fairborn Observatories. Maps of the distribution of the spotted regions on the photosphere of the binary components were derived using the Maximum Entropy and Tikhonov photometric regularization criteria. Rotational modulation was observed in Halpha and He I D-3 in anti-correlation with the photometric light curves. Both flares occurred at the same binary phase (0.85), suggesting that these events took place in the same active region. Simultaneous X-ray observations, performed by ASM on board RXTE, show several flare-like events, some of which correlate well with the observed optical flares. Rotational modulation in the X-ray light curve has been detected with minimum flux when the less active G5 V star was in front. A possible periodicity in the X-ray flare-like events was also found.

Ca(2+) sparks promote myogenic tone in retinal arterioles

Background and Purpose: Ca(2+) imaging reveals subcellular Ca(2+) sparks and global Ca(2+) waves/oscillations in vascular smooth muscle. It is well established that Ca(2+) sparks can relax arteries, but we have previously reported that sparks can summate to generate Ca(2+) waves/oscillations in unpressurized retinal arterioles, leading to constriction. We have extended these studies to test the functional significance of Ca(2+) sparks in the generation of myogenic tone in pressurized arterioles.

Experimental Approach: Isolated retinal arterioles (25-40 μm external diameter) were pressurized to 70 mmHg, leading to active constriction. Ca(2+) signals were imaged from arteriolar smooth muscle in the same vessels using Fluo4 and confocal laser microscopy.

Key Results: Tone development was associated with an increased frequency of Ca(2+) sparks and oscillations. Vasomotion was observed in 40% of arterioles and was associated with synchronization of Ca(2+) oscillations, quantifiable as an increased cross-correlation coefficient. Inhibition of Ca(2+) sparks with ryanodine, tetracaine, cyclopiazonic acid or nimodipine, or following removal of extracellular Ca(2+) , resulted in arteriolar relaxation. Cyclopiazonic acid-induced dilatation was associated with decreased Ca(2+) sparks and oscillations but with a sustained rise in the mean global cytoplasmic [Ca(2+) ] ([Ca(2+) ]c ), as measured using Fura2 and microfluorimetry.

Conclusions and Implications: This study provides direct evidence that Ca(2+) sparks can play an excitatory role in pressurized arterioles, promoting myogenic tone. This contrasts with the generally accepted model in which sparks promote relaxation of vascular smooth muscle. Changes in vessel tone in the presence of cyclopiazonic acid correlated more closely with changes in spark and oscillation frequency than global [Ca(2+) ]c , underlining the importance of frequency-modulated signalling in vascular smooth muscle.

A spectral synthesis code for rapid modelling of supernovae

We present TARDIS-an open-source code for rapid spectral modelling of supernovae (SNe). Our goal is to develop a tool that is sufficiently fast to allow exploration of the complex parameter spaces of models for SN ejecta. This can be used to analyse the growing number of highquality SN spectra being obtained by transient surveys. The code uses Monte Carlo methods to obtain a self-consistent description of the plasma state and to compute a synthetic spectrum. It has a modular design to facilitate the implementation of a range of physical approximations that can be compared to assess both accuracy and computational expediency. This will allow users to choose a level of sophistication appropriate for their application. Here, we describe the operation of the code and make comparisons with alternative radiative transfer codes of differing levels of complexity (SYN++, PYTHON and ARTIS). We then explore the consequence of adopting simple prescriptions for the calculation of atomic excitation, focusing on four species of relevance to Type Ia SN spectra-Si II, SII, MgII and Ca II. We also investigate the influence of three methods for treating line interactions on our synthetic spectra and the need for accurate radiative rate estimates in our scheme.

Office of the City Clerk, St. Catharines Records, 1928-1974, n.d.

The site of present-day St. Catharines was settled by 3000 United Empire Loyalists at the end of the 18th century. From 1790, the settlement (then known as "The Twelve") grew as an agricultural community. St. Catharines was once referred to Shipman's Corners after Paul Shipman, owner of a tavern that was an important stagecoach transfer point. In 1815, leading businessman William Hamilton Merritt abandoned his wharf at Queenston and set up another at Shipman's Corners. He became involved in the construction and operation of several lumber and gristmills along Twelve Mile Creek. Shipman's Corners soon became the principal milling site of the eastern Niagara Peninsula. At about the same time, Merritt began to develop the salt springs that were discovered along the river which subsequently gave the village a reputation as a health resort. By this time St. Catharines was the official name of the village; the origin of the name remains obscure, but is thought to be named after Catharine Askin Robertson Hamilton, wife of the Hon. Robert Hamilton, a prominent businessman. Merritt devised a canal scheme from Lake Erie to Lake Ontario that would provide a more reliable water supply for the mills while at the same time function as a canal. He formed the Welland Canal Company, and construction took place from 1824 to 1829. The canal and the mills made St. Catharines the most important industrial centre in Niagara. By 1845, St. Catharines was incorporated as a town, with the town limits extending in 1854. Administrative and political functions were added to St. Catharines in 1862 when it became the county seat of Lincoln. In 1871, construction began on the third Welland Canal, which attracted additional population to the town. As a consequence of continual growth, the town limits were again extended. St. Catharines attained city status in 1876 with its larger population and area. Manufacturing became increasingly important in St. Catharines in the early 1900s with the abundance of hydro-electric power, and its location on important land and water routes. The large increase in population after the 1900s was mainly due to the continued industrialization and urbanization of the northern part of the city and the related expansion of business activity. The fourth Welland Canal was opened in 1932 as the third canal could no longer accommodate the larger ships. The post war years and the automobile brought great change to the urban form of St. Catharines. St. Catharines began to spread its boundaries in all directions with land being added five times during the 1950s. The Town of Merritton, Village of Port Dalhousie and Grantham Township were all incorporated as part of St. Catharines in 1961. In 1970 the Province of Ontario implemented a regional approach to deal with such issues as planning, pollution, transportation and services. As a result, Louth Township on the west side of the city was amalgamated, extending the city's boundary to Fifteen Mile Creek. With its current population of 131,989, St. Catharines has become the dominant centre of the Niagara region. Source: City of St. Catharines website http://www.stcatharines.ca/en/governin/HistoryOfTheCity.asp (January 27, 2011)

Niagara Falls Seminary [school for young Ladies] advertisement, ca. 1840

One broadside advertising the Niagara Falls Seminary [school for young Ladies], run by Mrs. Shotter of Drummondville, ca. 1840. The advertisement contains information about fees and courses, including a complete English education, music, French, drawing and flower painting, and dancing. The bottom of the page contains a list of references for Mrs. Shotter, including Ex-Consul Buchanan, Colonel Delatre, Rev. W. Leeming, Rector of Chippawa (all of Drummondville); Dr. Mewburn (Stamford); Rev. T.B. Fuller, Rector of Thorold; John Stayner, Esq., P.M. Queenston; William Gamble, Esq., Milton, near Toronto; and Hon. John Hamilton, Kingston.

Niagara Falls Seminary [school for young Ladies] advertisement, ca. 1840

One broadside advertising the Niagara Falls Seminary [school for young Ladies], run by Mrs. Shotter of Drummondville, ca. 1840. The advertisement contains information about fees and courses, including a complete English education, music, French, drawing and flower painting, and dancing. The bottom of the page contains a list of references for Mrs. Shotter, including Ex-Consul Buchanan, Colonel Delatre, Rev. W. Leeming, Rector of Chippawa (all of Drummondville); Dr. Mewburn (Stamford); Rev. T.B. Fuller, Rector of Thorold; John Stayner, Esq., P.M. Queenston; William Gamble, Esq., Milton, near Toronto; and Hon. John Hamilton, Kingston.

Multidisciplinary analysis of clinical cases: a transition towards active learning in dental education

In the past 2009/10 academic year, we took steps towards introduction of active methodologies, from a multidisciplinar approach, into a conventional lecture-based Dental Education program. We consolidated these practices in the current 2010/11 year, already within a new Bologna-adapted scheme. Transition involved (i) critical assessment of the limitations of traditional teaching (ii) identification of specific learning topics allowing for integration of contents, (iii) implementation of student-centred learning activities in old curricular plans (iv) assessment of students' satisfaction and perceived learning outcomes, (v) implementation of these changes in new Bologna-adapted curricula

Gap junction-mediated spontaneous Ca(2+) waves in differentiated cholinergic SN56 cells

Neuronal gap junctions are receiving increasing attention as a physiological means of intercellular communication, yet our understanding of them is poorly developed when compared to synaptic communication. Using microfluorimetry, we demonstrate that differentiation of SN56 cells (hybridoma cells derived from murine septal neurones) leads to the spontaneous generation of Ca(2+) waves. These waves were unaffected by tetrodotoxin (1microM), but blocked by removal of extracellular Ca(2+), or addition of non-specific Ca(2+) channel inhibitors (Cd(2+) (0.1mM) or Ni(2+) (1mM)). Combined application of antagonists of NMDA receptors (AP5; 100microM), AMPA/kainate receptors (NBQX; 20microM), nicotinic AChR receptors (hexamethonium; 100microM) or inotropic purinoceptors (brilliant blue; 100nM) was also without effect. However, Ca(2+) waves were fully prevented by carbenoxolone (200microM), halothane (3mM) or niflumic acid (100microM), three structurally diverse inhibitors of gap junctions, and mRNA for connexin 36 was detected by PCR. Whole-cell patch-clamp recordings revealed spontaneous inward currents in voltage-clamped cells which we inhibited by Cd(2+), Ni(2+) or niflumic acid. Our data suggest that differentiated SN56 cells generated spontaneous Ca(2+) waves which are propagated by intercellular gap junctions. We propose that this system can be exploited conveniently for the development of neuronal gap junction modulators.

Glacial-interglacial temperature change in the tropical West Pacific: a comparison of stalagmite-based paleo-thermometers

In the tropics, geochemical records from stalagmites have so far mainly been used to qualitatively reconstruct changes in precipitation, but several new methods to reconstruct past temperatures from stalagmite material have emerged recently: i) liquid–vapor homogenization of fluid inclusion water ii) noble gas concentrations in fluid inclusion water, iii) the partitioning of oxygen isotopes between fluid inclusion water and calcite, and iv) the abundance of the 13C18O16O (‘clumped’) isotopologue in calcite. We present, for the first time, a direct comparison of these four paleo-thermometers by applying them to a fossil stalagmite covering nearly two glacial–interglacial cycles (Marine Isotope Stages (MIS) 12–9) and to two modern stalagmites, all from northern Borneo. The temperature estimates from the different methods agree in most cases within errors for both the old and recent samples; reconstructed formation temperatures of the recent samples match within 2-sigma errors with measured cave temperatures. However, slight but systematic deviations are observed between noble gas and liquid–vapor homogenization temperatures. Whereas the temperature sensitivity of fluid inclusion δ18O and clumped isotopes is currently debated, we find that the calibration of Tremaine et al. (2011) for fluid inclusion δ18O and a synthetic calcite-based clumped isotope calibration (Ziegler et al., in prep.) yield temperature estimates consistent with the other methods. All methods (with the potential exception of clumped isotopes) show excellent agreement on the amplitude of glacial–interglacial temperature change, indicating temperature shifts of 4–5 °C. This amplitude is similar to the amplitude of Mg/Ca-based regional sea surface temperature records, when correcting for sea level driven changes in cave elevation. Our reconstruction of tropical temperature evolution over the time period from 440 to 320 thousand years ago (ka) adds support to the view that climate sensitivity to varying greenhouse forcing is substantial also in the deep tropics.

Genomic and nongenomic dose-dependent biphasic effect of aldosterone on Na(+)/H(+) exchanger in proximal S3 segment: role of cytosolic calcium

Leite-Dellova DC, Oliveira-Souza M, Malnic G, Mello-Aires M. Genomic and nongenomic dose-dependent biphasic effect of aldosterone on Na(+)/H(+) exchanger in proximal S3 segment: role of cytosolic calcium. Am J Physiol Renal Physiol 295: F1342-F1352, 2008. First published August 20, 2008; doi:10.1152/ajprenal.00048.2008.-The effects of aldosterone on the intracellular pH recovery rate (pHirr) via Na(+)/H(+) exchanger and on the [Ca(2+)](i) were investigated in isolated rat S3 segment. Aldosterone [10(-12), 10(-10), or 10(-8) M with 1-h, 15- or 2-min preincubation (pi)] caused a dose-dependent increase in the pHirr, but aldosterone (10(-6) M with 1-h, 15- or 2-min pi) decreased it (these effects were prevented by HOE694 but not by S3226). After 1 min of aldosterone pi, there was a transient and dose-dependent increase of the [Ca(2+)](i) and after 6-min pi there was a new increase of [Ca(2+)](i) that persisted after 1 h. Spironolactone, actinomycin D, or cycloheximide did not affect the effects of aldosterone (15 -or 2-min pi) but inhibited the effects of aldosterone (1-h pi) on pHirr and on [Ca(2+)](i). RU 486 prevented the stimulatory effect of aldosterone (10(-12) M, 15 -or 2-min pi) on both parameters and maintained the inhibitory effect of aldosterone (10(-6) M, 15- or 2-min pi) on the pHirr but reversed its stimulatory effect on the [Ca(2+)](i) to an inhibitory effect. The data indicate a genomic (1 h, via MR) and a nongenomic action (15 or 2 min, probably via GR) on [Ca(2+)](i) and on the basolateral NHE1 and are compatible with stimulation of the NHE1 by increases in [Ca(2+)](i) in the lower range (at 10(-12) M aldosterone) and inhibition by increases at high levels (at 10(-6) M aldosterone) or decreases in [Ca(2+)](i) (at 10(-6) M aldosterone plus RU 486).

Effect of temporary cements on the shear bond strength of luting cements

Objective: The purpose of this study was to evaluate, by shear bond strength (SBS) testing, the influence of different types of temporary cements on the final cementation using conventional and self-etching resin-based luting cements. Material and Methods: Forty human teeth divided in two halves were assigned to 8 groups (n=10): I and V (no temporary cementation); II and VI: Ca(OH)(2)-based cement; III and VII: zinc oxide (ZO)based cement; IV and VIII: ZO-eugenol (ZOE)-based cement. Final cementation was done with RelyX ARC cement (groups I to IV) and RelyX Unicem cement (groups V to VIII). Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. Results: Means were (MPa): I - 3.80 (+/- 1.481); II - 5.24 (+/- 2.297); III - 6.98 (+/- 1.885); IV - 6.54 (+/- 1.459); V - 5.22 (+/- 2.465); VI - 4.48 (+/- 1.705); VII - 6.29 (+/- 2.280); VIII - 2.47 (+/- 2.076). Comparison of the groups that had the same temporary cementation (Groups II and VI; III and VII; IV and VIII) showed statistically significant difference (p<0.001) only between Groups IV and VIII, in which ZOE-based cements were used. The use of either Ca(OH) 2 based (Groups II and VI) or ZO-based (Groups III and VII) cements showed no statistically significant difference (p>0.05) for the different luting cements (RelyX (TM) ARC and RelyX (TM) Unicem). The groups that had no temporary cementation (Groups I and V) did not differ significantly from each other either (p>0.05). Conclusion: When temporary cementation was done with ZO- or ZOE-based cements and final cementation was done with RelyX ARC, there was an increase in the SBS compared to the control. In the groups cemented with RelyX Unicem, however, the use of a ZOE-based temporary cement affected negatively the SBS of the luting agent used for final cementation.

Muscular coactivation (CA) around the knee reduces power production in elderly women

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tetradentate schiff base copper(II) complexes

Ten copper(II) complexes of tetradentate Schiff bases obtained by condensing two moles of an o-hydroxyphenylcarbonyl compound with a diamine have been prepared and characterized by elemental analyses, melting points, IR and electronic spectra. The IR and electronic spectra of the free ligand and the complexes are compared and discussed. The deconvolution of the visible spectra of the complexes in CHCl3, approximately C2v or C1, yielded four peaks at ca. 15000, 17000, 18000-19000, and 20000-22000 cm-1, assigned to the four d-d transitions.

The efficacy of the self-adjusting file and ProTaper for removal of calcium hydroxide from root canals

Objective: The goal of this study was to evaluate the efficacy of the Self-Adjusting File (SAF) and ProTaper for removing calcium hydroxide [Ca(OH)2] from root canals. Material And Methods: Thirty-six human mandibular incisors were instrumented with the ProTaper system up to instrument F2 and filled with a Ca(OH)2-based dressing. After 7 days, specimens were distributed in two groups (n=15) according to the method of Ca(OH)2 removal. Group I (SAF) was irrigated with 5 mL of NaOCl and SAF was used for 30 seconds under constant irrigation with 5 mL of NaOCl using the Vatea irrigation device, followed by irrigation with 3 mL of EDTA and 5 mL of NaOCl. Group II (ProTaper) was irrigated with 5 mL of NaOCl, the F2 instrument was used for 30 seconds, followed by irrigation with 5 mL of NaOCl, 3 mL of EDTA, and 5 mL of NaOCl. In 3 teeth Ca(OH)2 was not removed (positive control) and in 3 teeth canals were not filled with Ca(OH)2 (negative control). Teeth were sectioned and prepared for the scanning electron microscopy. The amounts of residual Ca(OH)2 were evaluated in the middle and apical thirds using a 5-score system. Results: None of the techniques completely removed the Ca(OH)2 dressing. No difference was observed between SAF and ProTaper in removing Ca(OH)2 in the middle (P=0.11) and the apical (P=0.23) thirds. Conclusion: The SAF system showed similar efficacy to rotary instrument for removal of Ca(OH)2 from mandibular incisor root canals.