Comparison of two techniques for assessing the shaping efficacy of repeatedly used nickel-titanium rotary instruments

Introduction

The shaping capacity of nickel-titanium (NiTi) rotary instruments is often assessed by photographic or micro-computed tomography (micro-CT) measurements, and these instruments are often used more than once clinically. This study was conducted to compare photographic and micro-CT measurements and to assess if the repeated use of NiTi instruments affected the shape of canal preparation.

Methods

Ten new sets of ProTaper Universal instruments (Dentsply-Maillefer, Ballaigues, Switzerland) were used in 60 resin blocks simulating curved root canals. Groups 1 to 6 (n = 10) represented the first to sixth use of the instrument, respectively. Digitized images of the prepared blocks were taken in both mesiodistal (MD) and buccolingual (BL) directions and area measurements (mm²) were calculated using AutoCAD (Autodesk Inc, San Rafael, CA). The volumes of the same prepared canals were measured using micro-CT (mm³). Statistical analysis was performed to detect differences between photographic and volumetric measurements and differences between uses.

Results

Two-way repeated-measures analysis of variance revealed significant differences between groups (P < .001). Regarding measurement type, there were no significant differences between BL and MD measurements, but there were significant differences between micro-CT and BL measurements (P < .001) and micro-CT and MD measurements (P = .001). Significant differences were also noted between uses.

Conclusions

Within the limitations of the present study, micro-CT scanning is more discriminative of the changes in canal space associated with repeated instrument use than photographic measurements. Canal preparations are significantly smaller after the third use of the same instrument.     

Differentiation of arginine vasopressin antagonistic effects by selective V2 versus dual V2/V1a receptor blockade in a preclinical heart failure model

Arginine vasopressin (AVP) is increased in patients with heart failure (HF). Its actions are linked to free water reabsorption (V2-) and arteriolar vasoconstriction (V1a receptor). AVP can exacerbate the cardiorenal syndrome with excess fluid retention and afterload increase. Tolvaptan (TOL; selective V2 antagonist) and Conivaptan (CON; dual V1a/V2 antagonist) are two AVP antagonists that counteract the action of AVP with distinct profiles. We investigated the therapeutic effects of CON and TOL in an acute HF model. Mongrel dogs were paced continuously at 220 beats/min. After 14 days, the animals underwent acute testing. Dogs were instrumented to measure cardiac output, blood pressure, pulmonary artery pressure, and left ventricular dP/dtmax. Additionally, during the acute experiments, vasopressin was infused intravenously (4 mU/kg/min) to achieve constant and controlled pathophysiological levels of AVP. Subsequently, animals received either CON or TOL (n = 6; 0.1-mg/kg bolus). There were no significant differences in effect on mean arterial pressure, dP/dtmax, central venous pressure, and urine output between CON and TOL. In contrast, cardiac output increased by 0.15 l/min after CON and decreased by 0.6 l/min after TOL (P < 0.01). Accordingly, the total peripheral resistance increased after TOL by 250 dyn*s/cm and decreased after CON by 125 dyn*s/cm (P < 0.01). In conclusion, it was demonstrated that in an acute HF model, CON lowered, whereas TOL increased afterload. The results suggest that dual V1a/V2 blockade in the acute HF setting could be beneficial compared with selective V2 blockade. Chronic experiments are needed to determine whether this finding can translate into a sustained clinical advantage.     

Identification of the major allergen of Macrobrachium rosenbergii (giant freshwater prawn)

Objective

To characterize the major allergens of Macrobrachium rosenbergii (giant freshwater prawn).

Methods

Raw and cooked extracts of the giant freshwater prawn were prepared. The IgE reactivity pattern was identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting technique with the sera of 20 skin prick test (SPT) positive patients. The major allergen identified was then characterized using the proteomics approach involving a combination of two-dimensional (2-DE) electrophoresis, mass spectrometry and bioinformatics tools.

Results

SDS-PAGE of the raw extract showed 23 protein bands (15–250 kDa) but those ranging from 40 to 100 kDa were not found in the cooked extract. From immunoblotting experiments, raw and cooked extracts demonstrated 11 and 5 IgE-binding proteins, respectively, with a molecular mass ranging from 15 to 155 kDa. A heat-resistant 36 kDa protein was identified as the major allergen of both extracts. In addition, a 42 kDa heat-sensitive protein was shown to be a major allergen of the raw extract. The 2-DE gel fractionated the prawn proteins to more than 50 different protein spots. Of these, 10 spots showed specific IgE reactivity with patients'' sera. Matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis led to identification of 2 important allergens, tropomyosin and arginine kinase.

Conclusions

It can be concluded that the availability of such allergens would help in component-based diagnosis and therapy of prawn allergies.     

Resting heart rate in patients with ischemic heart disease in Saudi Arabia and Egypt

Aim

To assess the level of resting heart rate (RHR) in an outpatient population presenting with stable coronary artery disease (CAD) as well as to measure its association with current therapeutic management strategies for cardiovascular events.

Materials and methods

A multi-center cross-sectional survey was carried out in Saudi Arabia and Egypt over a three month period (between January 2007 and April 2007). 2049 patients with CAD without clinical heart failure (HF) were included in this study through “cluster sampling”. RHR was measured by manual palpitation.

Results

Mean age of CAD patients was 56.7 ± 10.4 and the mean RHR was 78.9 ± 13.9 b/m. 1686 patients (83.1%) were on β-blockers for whom the RHR was 78.5 ± 14.0 b/m (95.5% had RHR ⩾ 60 b/m, which is higher than recommended by the guidelines). 1094 (73.5%) of patients on β-blockers were on a lower dose, probably to avoid the complications associated with such a class. Among those not on β-blockers (16.9%), RHR was 80.9 ± 13.0 b/m.Moreover, 98 patients (4.8%) were on calcium channel blocker (diltiazem or verapamil) but not on β-blockers, for whom the RHR was 80.9 ± 12.0 b/m. Finally, 163 patients (8.0%) were on both β-blockers and the calcium channel blocker, and their RHR was 79.0 ± 14.4 b/m.

Conclusion

Optimal target RHR has not been achieved in a significant number of screened patients. Achievements of such targets are known to decrease mortality and to improve survival.Abbreviations: RHR, resting heart rate; CAD, coronary artery disease; NYHA, New York Heart Association Classification; HF, heart failure     

Can Myocardial Strain Differentiate Hypertrophic from Infiltrative Etiology of a Thickened Septum?

Objectives: Radial systolic strain (?) assessed by echocardiography has been shown to identify patterns of normal septal motion brought about by different layers, including left ventricular (LV) subendocardial (LV subendo) and mural (LV mural) layers. We aimed to use myocardial strain in assessing radial and longitudinal myocardial function in normal and thickened septum and to test if myocardial strain can differentiate hypertrophic from infiltrative cause of thickened septum. Methods: Forty‐five patients (age 61 ± 13 years, 22 males), 13 with hypertrophic cardiomyopathy, 15 with aortic stenosis, and 17 with familial amyloid polyneuropathy, were studied and compared with 29 controls (age 61 ± 12 years, 17 males) using 1D strain and conventional echocardiography. Results: Patients had normal LV ejection fraction and stroke volume but heart rate was higher (P < 0.05) compared to controls. Septal ? was reduced (–7.6 ± 7.0% vs. –14.0 ± 5.5%, for LV mural and –7.9 ± 14.7% vs. –20.3 ±–7.9% for LV subendo, P < 0.001 for both layers) across LV longitudinal axis but not along its radial axis. No difference was found in any of ? measurements between patient groups. A decrease in strain length by 50% increased the septal strain by more than 60% in both radial and longitudinal axes. Conclusion: Septal systolic strain measurements showed reduced longitudinal function but its localized nature failed to demonstrate radial disturbances in patients with pathologically thickened septum. No difference was found in systolic strain between patients according to the etiology of septal thickness. This limitation might be either technical or is explained by the maintained radial function in all patient groups. (Echocardiography 2011;28:408‐415)     

Prenatal Diagnosis of Isolated Levocardia and a Structurally Normal Heart: Two Case Reports and a Review of the Literature

Isolated levocardia (ILC) is a developmental abnormality involving an abnormal abdominal situs with a normal cardiac situs. This abnormality is especially rare when it is associated with a normal cardiac anatomy. The prenatal diagnoses of seven cases were reported in the English literature. This report presents two cases referred to the authors’ echocardiography laboratory for maternal diabetes mellitus in case 1 and suspected dextrocardia in case 2. In both cases, ILC with a structurally normal heart was diagnosed prenatally. The child in the first case was found to have a normal inferior vena cava (IVC) prenatally. Postnatally, he was found to have intestinal malrotation with duodenal obstruction and multiple splenules. Interruption of the IVC was shown by abdominal ultrasound. The child in the second case was found to have an interrupted IVC with azygos continuation prenatally. Postnatally, intestinal malrotation with no evidence of intestinal obstruction or asplenia was detected. Neither of the cases had reported cardiac arrhythmias. Early diagnosis is crucial in these cases due to the high incidence of associated anomalies and potential life-threatening conditions. Management of patients with ILC is dictated by the associated anomalies. Long-term follow-up assessment is recommended for these patients to monitor the development of rhythm abnormalities.