Decrease in the fatigue resistance of nickel-titanium rotary instruments after clinical use in curved root canals.

OBJECTIVE: The changes in fatigue resistance of nickel-titanium rotary ProFile instruments after clinical use for shaping 10 curved molar root canals were evaluated in this study. STUDY DESIGN: Twenty-five sets of files #20, #25, and #30 and tapers .04 and .06 were divided into 2 groups, one with 10 sets of new files that were tested in a fatigue test bench device as a control. The other, experimental group, with 15 sets of clinically used files, was tested in the same device. The Student t test was employed to compare mean values of the measured parameters. RESULTS: A statistically significant decrease in the number of cycles to failure was determined for the clinically used files, as compared with the new ones. The fracture point was the same for all files tested. CONCLUSIONS: The clinical use of ProFile instruments for shaping curved canals reduces their fatigue resistance.     

Small Conductance Ca2+-Activated K+ Channels Formed by the Expression of Rat SK1 and SK2 Genes in HEK 293 Cells

The rat SK1 gene ( rSK1 ) does not form functional Ca²⁺-activated potassium channels when expressed alone in mammalian cell lines. Using a selective antibody to the rSK1 subunit and a yellow fluorescent protein (YFP) tag we have discovered that rSK1 expression produces protein that remains largely at intracellular locations. We tested the idea that rSK1 may need an expression partner, rSK2, in order to form functional channels. When rSK1 was co-expressed with rSK2 in HEK 293 cells it increased the current magnitude by 77 ± 34 % (as compared with cells expressing rSK2 alone). Co-expression of rSK1 with rSK2 also changed the channel pharmacology. The sensitivity of SK current to block by apamin was reduced ~16-fold from an IC₅₀ of 94 p m (for SK2 alone) to 1.4 n m (for SK2 and SK1 together). The sensitivity to block by UCL 1848 (a potent small molecule blocker of SK channels) was similarly reduced, ~26-fold, from an IC₅₀ of 110 p m to 2.9 n m . These data clearly demonstrate that rSK1 and rSK2 subunits interact. The most likely explanation for this is that the subunits are able to form heteromeric assemblies.     

Colorimetric analysis of some diuretic drugs: hydrochlorothiazide and spironolactone

Two convenient spectrophotometric methods were developed for the determination of hydrochlorothiazide and spironolactone. A specific colour reaction for the determination of hydrochlorothiazide is reported. One method is based on the reaction of hydrochlorothiazide withn-butylamine and cobaltous chloride in anhydrous methanol. A blue-violet colour is produced and is measured at 570 nm. A highly selective colorimetric method was adopted for the analysis of spironolactone by reacting with isoniazid forming a coloured hydrazone derivative and subsequent measurement of the coloured product at 405 nm.From Determination of certain diuretics, M Pharm Sci thesis.The volumetric flasks were dried by rinsing them with pure acetone after draining off the water, then allowing to drain until dry or blowing air through them.     

Abdominal Aortic Aneurysms: Endovascular Options and Outcomes — Proliferating Therapy,But Effective?

Abdominal aortic aneurysm (AAA) has a reported prevalence rate of 1.4% in the US. AAA rupture accounts for an estimated 15,000 deaths per year, rendering it the 10th leading cause of death in men over the age of 55. Endovascular repair (EVR) has proliferated in the last two decades as an increasingly popular alternative to traditional open surgery, and is now the default treatment in the majority of centres worldwide. This review article outlines the evidence supporting this stance. The development of EVR is reviewed, alongside trends in utilisation of this therapy over time. The evidence for the relative short-term and long-term outcomes of EVR and open AAA repair is discussed, and ongoing controversies surrounding the use of EVR are considered.