Comparison of flexural properties of composite restoratives using the ISO and mini-flexural tests

The purpose of this study was to investigate the flexural properties (flexural strength and flexural modulus) of four commercial composite restoratives (Silux Plus, Z100, Ariston and Surefil) using the ISO 4049 flexural test (IFT) and a mini-flexural test (MFT). Both tests involved the use of three-point loading and the same fixture. The difference between the tests was in the length of the composites specimens and the distance between the supports [20 mm (IFT) and 10 mm (MFT)]. Six specimens were made for each material and flexural test. Test specimens [25 x 2 x 2 mm (IFT) and 12 x 2 x 2 mm (MFT)] were fabricated according to manufacturers' recommendations. After light-polymerization, the specimens were stored in distilled water at 37 degrees C for 24 h. The specimens were subsequently blotted dry, measured and subjected to flexural testing using an Instron Universal Testing Machine with a crosshead speed of 0.75 mm min(-1). Data was analysed using anova/Scheffe's, paired samples test (P < 0.05) and Pearson's correlation (P < 0.01). For both IFT and MFT, results of statistical analysis of flexural strength were identical. Silux had significantly lower flexural strength compared with the other composites and the flexural strength of Ariston was significantly lower than Z100 and Surefil. For IFT, the flexural modulus of Z100 was significantly higher than Silux, Ariston and Surefil while for MFT, Silux had significantly lower modulus compared with Z100, Ariston and Surefil. A significant, strong and positive correlation (r = 0.95) was observed for flexural strength between IFT and MFT. Correlation for flexural modulus was also significant and positive but was weaker (r = 0.53). As MFT has the advantage of ease of specimen fabrication and is more clinically realistic, it is suggested for the testing of composite restoratives. CLINICAL RELEVANCE: The mini-flexural test may be better than the ISO flexural test for screening of composite restoratives for clinical applications.     

Ultrasound detection of the Essure permanent birth control device: a case series

BACKGROUND: The current recommendation to check the position of the Essure permanent birth control (PBC) micro-insert device after its insertion is by abdominal X-ray 3 months after insertion. We propose that ultrasound imaging is more suited for this purpose and gives reassurance much earlier. The sonographic appearance of the micro-inserts and the reliability of this modality in localising the devices is described in the present study. OBJECTIVE: To ascertain the appearance of the Essure PBC device at transvaginal and transabdominal ultrasound scanning and to determine the reliability of this approach in localising the contraceptive device. Study population and methods: All patients who had the Essure PBC procedure between June 2002 and January 2003 at our centre were offered an ultrasound scan to check device position. RESULTS: The micro-inserts were easily distinguished by their echogenic coil-like appearance within each uterine cornua extending into the proximal fallopian tube. Of the 15 patients examined, 14 pairs of devices were seen: one device was malpositioned in the lower part of the uterus. In one patient, only one device was seen in the correct position but the other device was not identified and presumably expelled after a notably difficult insertion. DISCUSSION: Ultrasound appears to be well suited for micro-insert localisation. An early post insertion ultrasound scan is recommended to reassure about correct positioning of device and may potentially alleviate patient anxiety, or diagnose malposition early.     

Utility of portable continuous-wave Doppler examination in screening for postoperative deep vein thrombosis

BACKGROUND: Early and accurate diagnosis of post-surgical deep vein thrombosis (DVT) can be difficult and time-consuming, even with duplex ultrasonography. Portable continuous-wave Doppler ultrasonography may be useful in screening patients for postoperative DVT. Further confirmation of Doppler-positive cases by duplex ultrasound might then be more cost-effective. METHODS: All major post-surgical patients from the departments of general surgery, orthopaedic surgery and colorectal surgery were screened on the third postoperative day for DVT by assessing the quality of the flow signal ("whoosh") obtained by placing the probe over the femoral vein and subsequently over the popliteal vein, both with a distal squeeze, as well as assessment of phasic flow with respiration. An absent or attenuated "whoosh" was judged to be suspicious for DVT and required formal duplex ultrasonography. The first 800 consecutive patients were studied to determine the sensitivity, specificity and accuracy of portable Doppler ultrasonography for DVT screening. RESULTS: Twenty-four cases of DVT were diagnosed, comprising seven cases in the proximal veins and 17 cases in the calf veins. The sensitivity of Doppler ultrasonography was 12.5% and the specificity was 96.8%. The positive and negative predictive values were 10.7% and 97.3%, respectively. CONCLUSIONS: Portable Doppler ultrasonography does not have adequate accuracy to be used as a quick screening tool for DVT.     

Agreements between the prothrombin times of blood treated In Vitro with heparinase during cardiopulmonary bypass (CPB) and blood sampled after CPB and systemic protamine

The prothrombin time (PT) is useful for identifying coagulation factor deficits after cardiopulmonary bypass (CPB). However, long processing times and the need for fresh frozen plasma (FFP) to be thawed cause delays in factor replacement. We hypothesized that, by treating with heparinase, blood sampled toward the end of CPB can provide PT results that help to determine the requirement for FFP after CPB. Laboratory delays can be eliminated with point-of-care monitors. We studied 158 adults undergoing nonemergent cardiac surgery. Blood taken before separation from CPB was mixed with heparinase, and PT was measured in the laboratory with a HemoTec timer. Agreements between these results and laboratory measurements of blood taken after systemic protamine were compared by using Bland and Altman plots with the threshold of +/-1.0 s. We found that the laboratory PT measurements during CPB versus after CPB were compara-ble, but the limits of agreement exceeded these thresholds. Similarly, there was unsatisfactory agreement between the HemoTec and laboratory PT results measured before, during, and after CPB. For each PT measured during CPB, the corresponding confidence interval for the postprotamine PT was calculated. During CPB, a laboratory PT of < or =16 s or > or =18 s suggests a > or =83% or > or =93% probability of not requiring or potentially requiring, respectively, FFP after CPB. We conclude that the majority of PT measurements obtained from blood taken before weaning from CPB and treated in vitro with heparinase was associated with a high probability of whether or not FFP would be needed after CPB. IMPLICATIONS: Coagulation dysfunction after cardiopulmonary bypass may contribute to bleeding. Obtaining coagulation tests and fresh frozen plasma requires time and delays treatment in patients who need fresh frozen plasma. We have devised a technique to provide early estimation of postbypass coagulation status.     

Detrimental effects of papaverine on the human internal thoracic artery

OBJECTIVE: We sought to determine the effects of papaverine on human and canine internal thoracic artery function and structure. METHODS: Vascular function was assessed with wire myography, and apoptosis was examined with confocal microscopy in arteries stained with ApopTag. RESULTS: Acetylcholine-induced endothelium-dependent relaxation in phenylephrine-precontracted arteries was significantly impaired by papaverine treatment in both human and canine internal thoracic arteries (maximal relaxation: 68.35% +/- 7.13% vs 47.5% +/- 9.32% in human arteries and 74.8% +/- 5.5% vs 34.3% +/- 8.5% in canine arteries) but not by incubation with acidified saline solution (pH 3.9, which is equivalent to the pH of 10(-2) mol/L papaverine solution) in canine internal thoracic arteries. Contraction of human internal thoracic arteries to phenylephrine or to U46619 was not significantly affected by papaverine treatment and neither was the contraction of canine internal thoracic arteries to phenylephrine. Total apoptotic endothelial and smooth muscle cells were significantly greater in papaverine-treated human and canine internal thoracic arteries. CONCLUSIONS: Papaverine impairs endothelial function and triggers apoptosis of endothelial and smooth muscle cells of human and canine internal thoracic arteries. The long-term consequence of this impairment on vascular function is not known. Until this question is answered, it will be prudent to use other vasodilators that are less damaging to the internal thoracic artery for cardiac surgery.     

Role of Cl- currents in rat aortic smooth muscle activation by prostaglandin F2 alpha

The aim of this study was to determine the role of Cl(-) channel activation in prostaglandin F(2 alpha)-stimulated aortic contraction and in membrane depolarization during stimulation with prostaglandin F(2 alpha) in an aortic smooth muscle cell line (A7r5). The Cl(-) channel antagonists 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), indanyloxyacetic acid-94 (IAA-94) and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) were found to decrease (P<0.05) the maximum tension generated by rat thoracic aortic segments during stimulation with prostaglandin F(2 alpha) and to shift the concentration-response relationship to the right. In the presence of Nifedipine and Cesium, rat aorta-derived A7r5 smooth muscle cells demonstrated outwardly rectifying voltage-dependent currents that were inhibited by NPPB, IAA-94 and DIDS. Both inward and outward currents were enhanced (P<0.05) following addition of prostaglandin F(2 alpha) (4 micromol/l, final concentration) to the bath solution and this increase was completely inhibited by NPPB. In the absence of Cesium, the addition of prostaglandin F(2 alpha) (4 micromol/l) to the extracellular bath solution either depolarized or hyperpolarized the cell membrane depending on the equilibrium potential for Cl(-) ions. Our results indicate that altered Cl(-) conductance is an important mechanism mediating membrane depolarization and contraction of aortic smooth muscle cells during stimulation with prostaglandin F(2 alpha). Given the significant role that prostaglandin F(2 alpha) and its biologically active isomers, the F(2) isoprostanes, play in the control of vascular tone during hypoxic and oxidative stress in the systemic circulation, alterations in Cl(-) channel function and expression may represent an important mechanism in the pathogenesis of abnormal blood flow regulation in disease states.