Neoaortic aneurysm after stage I Norwood reconstruction

Treatment of hypoplastic left heart syndrome through staged repairs has resulted in patients surviving into adulthood. Use of either aortic or pulmonary homografts in performing the neoaortic reconstruction has become the standard of practice with relatively few problems. We report the case of an asymptomatic adolescent boy who had an enlarging neoaortic aneurysm and mild neoaortic regurgitation develop after undergoing a stage I Norwood procedure using a pulmonary homograft. Given the risk for rupture and a concern for further functional deterioration of the neoaortic valve, the patient underwent repair. Histologic examination showed a striking accumulation of myxoid material as well as abnormal vasculature in both the native and engrafted portions of the neoaorta.     

Clinical skills: the physiological basis and interpretation of the ECG

Electrocardiograph (ECG) interpretation is a complex subject that requires considerable experience. However, an understanding of the principles underlying generation of the ECG can make this learning process easier. This knowledge is necessary if interpretation is to be founded on understanding rather than being a pattern recognition-based process. The aim of this article is to introduce the practitioner to the basic processes and mechanisms that govern formation of the normal ECG. These principles will largely be applied to the normal ECG and include cardiac anatomy applied to the ECG, how the ECG leads look at the heart and how the normal ECG waveform is formed. Examples of how the ECG changes when the underlying mechanisms are disturbed will also be given. Together, this knowledge should help the practitioner to have a clearer understanding of interpreting the abnormalities seen on an ECG.     

Assessment of flat panel LCD primary class display performance based on AAPM TG 18 acceptance protocol

The image display is an important component of the Picture Archiving and Communication System (PACS) and of digital imaging in general. In this paper, we assess the display performance of 32 different flat panel LCD devices, in terms of their reflection, luminance response, luminance uniformity, resolution, noise, veiling glare and color uniformity included in the tentative guidelines of the AAPM TG18 document version 8.1. We also report on the angular dependencies of luminance and contrast, which constitute one of the miscellaneous tests. The tools used included a telescopic photometer, which was also used as a colorimeter, an illuminance meter, light sources for the reflection assessment, light-blocking devices, and digital TG18 test patterns. The luminance ratio (LR), maximum luminance difference (ALmax) and deviation of contrast response with respect to that of DICOM GSDF were 379.2+/-61.0, 1.6+/-1.1%, and 4.84+/-0.58%, respectively. The maximum luminance nonuniformity was 9.2+/-3.9% for the 10% luminance of the TG18-UNL10 test pattern. In the luminance-based resolution test, the percent luminance difference (deltaL) at the center was 0.78+/-0.42%. In all cases of noise testing, the rectangular target in each square in the three quadrants was visible, as were all 15 targets, except for the smallest one, in each corner pattern and the center pattern. The glare ratio (GR) was 2350+/-1460. The average color uniformity parameter, delta(u',v'), across the display area of each display device was 0.002+/-0.001. Nevertheless, not all of the color uniformity parameters of the display devices associated with a workstation met the acceptance criteria. For 7 selected flat panel displays, the mean specular and diffuse reflection coefficients were 0.0061+/-0.0010 and 0.0017+/-0.0005 cd/m2 per lux, respectively. All of the test results conformed to the criteria recommended by AAPM TG18, indicating that the displays were fully acceptable for diagnostic image interpretation. The maximum viewing angle conforming to the DICOM 3.14 standard luminance responses with a 10% tolerance was found to be approximately 50 degrees in both directions along the vertical axis, 10 degrees in the upper direction and 20 degrees in the lower direction along the horizontal axis, and 20 degrees in the upper direction and 10 degrees in the lower direction along the diagonal axis. Therefore, a radiologist should interpret a displayed image by considering the physical characteristics of the narrow viewing angle of the AMLCD displays. The acceptance testing protocol described herein demonstrates the successful clinical implementation of the guidelines for the viewing conditions of medical displays, and if implemented with a QC program, can be used to determine when LCD devices used for diagnostic interpretation need to be upgraded.     

Pharmacokinetics of acyclovir in rabbit skin after i.v.-bolus, ointment, and iontophoretic administrations

The aim of this study was to characterize and compare the pharmacokinetics of acyclovir (ACV) in skin and plasma after iontophoresis, i.v.-bolus, and ointment administrations in rabbit. On five occasions, each separated by at least 1-week washout, rabbits received a 10 mg/kg dose of ACV as i.v.-bolus, ACV iontophoresis for 1 h at different current densities (100, 200, 300 microA/cm2) or a commercially available ointment for two hours. Blood samples were collected serially up to 6 h. Skin ACV concentrations were monitored via microdialysis using linear microdialysis probes (1 cm window). Cathodic iontophoresis was performed using commercially available patches (10 cm2 contact area). Following i.v.-bolus, C(max) in skin occurred with a delay of 38 +/- 4 min compared with plasma. No quantifiable concentration of ACV was detected in the skin on passive drug delivery. Following iontophoresis, skin exposure to ACV was 40, 22, and 11% of that following i.v.-bolus. Conversely, systemic exposure to ACV was negligible and plasma concentrations were below the limit of quantification at any time-point. In skin dialysate, C(max), AUC, and half-life increased with current density. During ointment application, ACV in dermis was detectable only for the first 30 min thereafter ACV skin concentrations were below the LOQ (30 ng/ml).     

Does image quality matter? Impact of resolution and noise on mammographic task performance

The purpose of this study was to examine the effects of different resolution and noise levels on task performance in digital mammography. This study created an image set with images at three different resolution levels, corresponding to three digital display devices, and three different noise levels, with noise magnitudes similar to full clinical dose, half clinical dose, and quarter clinical dose. The images were read by five experienced breast imaging radiologists. The data were then analyzed to compute two accuracy statistics (overall classification accuracy and lesion detection accuracy) and performance at four diagnostic tasks (detection of microcalcifications, benign masses, malignant masses, and discrimination of benign and malignant masses). Human observer results showed decreasing display resolution had little effect on overall classification accuracy and individual diagnostic task performance, but increasing noise caused overall classification accuracy to decrease by a statistically significant 21% as the breast dose went to one quarter of its normal clinical value. The noise effects were most prominent for the tasks of microcalcification detection and mass discrimination. When the noise changed from full clinical dose to quarter clinical dose, the microcalcification detection performance fell from 89% to 67% and the mass discrimination performance decreased from 93% to 79%, while malignant mass detection performance remained relatively constant with values of 88% and 84%, respectively. As a secondary aim, the image set was also analyzed by two observer models to examine whether their performance was similar to humans. Observer models differed from human observers and each other in their sensitivity to resolution degradation and noise. The primary conclusions of this study suggest that quantum noise appears to be the dominant image quality factor in digital mammography, affecting radiologist performance much more profoundly than display resolution.     

The effect of sodium valproate on acetic acid-induced colitis in rats

Ulcerative colitis is a chronic recurrent disease with incomplete treatment options. The current article evaluated the effect of sodium valproate on acetic acid-induced ulcerative colitis in rats. Rats were randomly distributed into six groups including Sham group, colitis control group, sodium valproate treatment groups (50, 100 and 300 mg/kg, i.p.) and dexamethasone-treatment group. Dexamethasone was used as a reference drug. Colitis was induced by intracolonic instillation of 2 mL of 3% acetic acid solution. The efficacy of sodium valproate was evaluated by macroscopical and histopathological scoring systems, hematocrit measurement as well as biochemical analysis including myeloperoxidase (MPO) and pro-inflammatory cytokines assessment. Sodium valproate, particularly with doses of 100 and 300 mg/kg significantly improved weight loss, and macroscopic damage, reduced ulcer area, colon weight, microscopic colitis index and elevated hematocrit level. Biochemical experiments showed elevated levels of colonic MPO activity, interleukin 1β (IL-1β), interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α) in colitis control group. Treatment with sodium valproate at the doses of 100 and 300 mg/Kg) decreased the MPO activity and colonic concentrations of IL-1β, IL-6 and TNF-α. The results provide evidence that sodium valproate has a protective effect in acetic acid-induced ulcerative colitis which might be due to its anti-inflammatory activities, and it may be useful in patients with ulcerative colitis.     

Online Spectroscopic Monitoring of Drug Release Kinetics from Nanostructured Dual-Stimuli-Responsive Conducting Polymer

Purpose

The potential of electrochemical/temperature dual stimuli-responsive conducting polymer to be used as general drug delivery systems. It allows on-demand release of incorporated drug is kinetically investigated in real time.

Methods

Online spectroscopic monitoring was used to investigate the electrochemically/thermally controlled release behavior of a model drug (naproxen) from drug-doped polypyrrole (DDPPy) film. Avrami’s equation has been used to study the kinetics and further analyzing has been carried out using the Arrhenius and the Eyring equations. Furthermore, drug release behavior, with two other electrochemical techniques was investigated.

Results

It was observed both temperature and electrical stimuli increase the rate of release while electrical potential has a greater effect as revealed in the values of release rate constant (from 0.0068 to 0.018 min^?1 at 37°C). It was also shown that a linear relationship exists between the applied electrical potentials and release activation parameters.

Conclusion

The electronic properties of the conducting polymer has an important role in release kinetics, there might be a single mechanism with the same limiting step. In addition, it was demonstrated the rate of drug release from DDPPy dramatically depends on the amounts as well as modes of applying potential which provides enhanced control of drug-release kinetics which can be accelerated or even sustained.