Development of novel tricalcium silicate-based endodontic cements with sintered radiopacifier phase.

OBJECTIVES: All implants, bone and endodontic cements need to be sufficiently radiopaque to be able to be distinguished from neighbouring anatomical structures post-operatively. For this purpose, radiopacifying materials are added to the cements to render them sufficiently radiopaque. Bismuth oxide has been quite a popular choice of radiopacifier in endodontic materials. It has been shown to cause dental discoloration. The aim of this study was to develop, characterize and assess the properties of tricalcium silicate cement with alternative radiopacifiers, which are either inter-ground or sintered to the tricalcium silicate cement. METHODS: Custom-made endodontic cements based on tricalcium silicate and 20 % barium, calcium or strontium zirconate, which were either inter-ground or sintered at high temperatures, were produced. The set materials stored for 28 days in Hank's balanced salt solution were characterized by scanning electron microscopy and X-ray diffraction analysis. Assessment of pH, leaching, interaction with physiological solution, radiopacity, setting time, compressive strength and material porosity were investigated. Mineral trioxide aggregate (MTA) Angelus was used as control. RESULTS: Addition of radiopacifying materials improved the radiopacity of the material. The sintered cements exhibited the formation of calcium zirconate together with the respective radiopacifier phase. All materials produced calcium hydroxide on hydration, which interacted with tissue fluids forming hydroxyapatite on the material surface. The physical properties of the tricalcium silicate-based cements were comparable to MTA Angelus. CONCLUSIONS: A novel method of producing radiopaque tricalcium silicate-based cements was demonstrated. The novel materials exhibited properties, which were either comparable or else improved over the control. CLINICAL RELEVANCE: The novel materials can be used to replace MTA for root-end filling, perforation repair and other clinical applications where MTA is indicated.

Late presentation and successful treatment of classical scimitar syndrome.

Scimitar syndrome is a form of partial anomalous pulmonary venous drainage that is dramatically visible on plain chest radiography (CXR). In these individuals the entire venous drainage from the right lung enters a single anomalous large vein that descends to the inferior vena cava. This descending vein is visible on CXR as a curvilinear density along the right heart border and resembles the curved Turkish sword that gives the condition its name. Scimitar syndrome forms part of the large spectrum of associated conditions known as venolobar syndrome. These include right lung hypoplasia or sequestered segments of right lung, congenital heart disease and various others. We report the case of a young woman who presented incidentally, with a murmur, at 16 years of age. Full investigation including angiography showed a large atrial septal defect with right heart dilation and scimitar syndrome. She underwent surgical correction with uneventful and complete correction by baffling of the scimitar vein from its entry into the inferior vena to the left atrium through the enlarged atrial septal defect.

Long-term preservation of left ventricular function in medically treated patients with coronary artery disease and persistent exercise-induced ischemia.

Little information is available on the long-term evolution of left ventricular function of medically treated patients with coronary artery disease and gross limitation of coronary flow reserve. The aim of this study was to assess the long-term evolution of effort tolerance and left ventricular function and their relation to the control of ischemic events in patients with coronary artery disease and prolonged inducible exercise-induced myocardial dysfunction who either declined or were ineligible for cardiac revascularization.

Specificity and sensitivity of exercise-induced ST segment elevation for detection of residual viability: comparison with fluorodeoxyglucose and positron emission tomography.

OBJECTIVES: We evaluated the sensitivity and specificity of exercise-induced ST segment elevation for the detection of residual myocardial viability. BACKGROUND: Assessment of residual viability after myocardial infarction is relevant for establishing indication for revascularization. We have previously shown that exercise-induced ST segment elevation is a marker of residual viability. METHODS: We studied 34 patients with a previous Q wave myocardial infarction (anterior in 21, inferior in 13) of whom 18 (group A) had exercise-induced ST segment elevation in more than one lead (mean [+/- SD] 1.8 +/- 0.9 mm, range 1 to 4) and 16 (group B) did not. All patients underwent rest technetium-99m methoxyisobutyl isonitrile single-photon emission computed tomography (SPECT), fluorine-18 (F-18) fluorodeoxyglucose positron emission tomography and coronary angiography. The time elapsed between the infarction and the viability study was 72 +/- 108 days (range 15 to 400) in group A and 516 +/- 545 days (range 14 to 1,800) in group B. RESULTS: The presence and site of previous infarction were confirmed by SPECT studies in all 34 patients. Uptake of F-18 fluorodeoxyglucose within the infarcted area was present in 18 of 18 patients in group A but in only 9 (56%) of 16 in group B (p < 0.01). In patients with an anterior infarction, the sensitivity, specificity and predictive accuracy of exercise-induced ST segment elevation for detection of residual viability were 82%, 100% and 86%, respectively (95% confidence intervals 46% to 83.5%, 59% to 100% and 55.6% to 87.1%, respectively). CONCLUSIONS: Exercise-induced ST segment elevation in infarct-related leads has a high specificity and acceptable sensitivity for detection of residual viability within the infarcted area.

Antiischemic effects of intravenous diazepam in patients with coronary artery disease.

Diazepam (DZP) is commonly used in treatment of patients with acute ischemic syndromes to allay anxiety, but benzodiazepines reduce myocardial contractility and increase myocardial blood flow. To investigate the antiischemic effect of DZP, we studied 13 patients with a positive exercise test and angiographically documented coronary artery disease. All patients were submitted to a randomized, placebo-controlled trial using 0.9% NaCl infusion as placebo and intravenous (i.v.) diazepam (0.1 mg/kg in 20 min). Exercise tests performed immediately after the infusions showed that as compared with placebo, DZP significantly prolonged time to 1-mm ST-segment depression (557 +/- 198 vs. 428 +/- 226 s, p < 0.0001) and total exercise duration (624 +/- 177 vs. 561 +/- 188 s, p < 0.007). Rate-pressure product (RPP) at 1-mm ST-segment depression was not significantly different with the two treatments. DZP significantly delays onset of exercise-induced myocardial ischemia in patients with coronary artery disease. Because RPP at onset of ischemia was similar to that recorded with placebo despite greater levels of external workload, the antiischemic action of DZP appears to be mediated, at least partially, by a reduction in myocardial oxygen consumption.

Blockade of natural and neuropeptide Y-induced carbohydrate feeding by a receptor antagonist PYX-2.

Neuropeptide Y (NPY injected into the paraventricular nucleus (PVN) of rats has a potent stimulatory effect specifically on carbohydrate intake. This study examined the behavioral effects of a newly synthesized NPY antagonist, PYX-2. After PVN injection of PYX-2 (50-900 pmoles) alone, a strong dose-dependent reduction in spontaneous carbohydrate intake at the onset of the dark cycle was observed in freely-feeding rats. Moreover, at even lower doses (12.5 and 25.0 pmoles), PYX-2 also blocked the stimulatory action of PVN NPY (100 pmoles) on carbohydrate ingestion. These results provide the first evidence for the existence of endogenous NPY receptors in mediating the action of exogenous NPY in the hypothalamus. They also constitute a crucial step in demonstrating a physiological function of these PVN NPY receptors specifically in controlling carbohydrate ingestion at the onset of the natural feeding cycle.

Prevalence of silent myocardial ischaemia during exercise stress testing. Its relation to effort tolerance and myocardial perfusion abnormalities.

The number of underperfused myocardial segments, the extent of coronary artery disease and the severity of impairment of coronary flow reserve were compared in 147 consecutive patients exhibiting painful or painless ischaemic ST segment depression on exercise testing. Of 147 patients, only 61 (41%) experienced angina (group 1) whilst 86 (59%) did not (group 2). In the two groups coronary disease was comparable for both extent and distribution, and neither the location of transient perfusion defects nor their relation to areas of old myocardial necrosis appeared to influence the presence or absence of chest pain. However, exercise duration, exercise time and rate-pressure product at the beginning of ischaemia were lower in group 1. Furthermore, a greater proportion of asymptomatic patients had only one ischaemic segment on 99mTc-MIBI perfusion scintigraphy. We conclude that: (1) in patients with effort angina and coronary disease, the incidence of electrocardiographic silent ischaemic events induced by exercise is similar to that observed in studies based on continuous ECG monitoring. (2) Exertional angina is more frequently associated with greater ischaemic areas and with more severe degrees of impairment of residual coronary flow reserve. (3) The presence of an old myocardial infarction does not appear to influence the incidence of ischaemic cardiac pain.

Stroke following acute myocardial infarction in diabetics.

To investigate the effect of diabetes on stroke after myocardial infarction (MI), we studied consecutive MI patients admitted to the coronary-care unit prospectively, and compared diabetics with non-diabetics. Seven per cent (11/148) of diabetics and 3% (8/297) of non-diabetics had a stroke within 1 month after MI (P = 0.020). Previous stroke and hypertension were significant risk factors for stroke after MI in diabetics, but there were no significant risk factors in non-diabetics. Hypertension was more frequent in diabetics with (12/14; 86%) than in diabetics without (63/134; 47%) a previous stroke (P less than 0.025). Severe hypotension was more frequent in diabetics (9/11) than in non-diabetics with stroke after MI (0/8) (P = 0.002). We conclude that hypertension is a risk factor for stroke after MI in diabetics, and that may be at risk for hypotensive stroke after MI. Stroke after MI may be more frequent in diabetics than in non-diabetics.

[Cerebellar hemorrhage and unilateral asterixis]. / Hémorragie cérébelleuse et astérixis unilatéral.

A hypertensive woman presented with asterixis ipsilateral to a cerebellar hemorrhage. Asterixis has not previously been described in association with a cerebellar lesion. The presence of asterixis in this patient may have been due to a reduction of afferent information through the loss of the dentato-thalamo-cortical input. Unilateral asterixis denotes a dysfunction of the mechanism underlying sustained muscular contraction and not a precise cerebral localisation.