Assessment of cardiac mass from tagged magnetic resonance images

Purpose

Tagged and cine magnetic resonance imaging (tMRI and cMRI) techniques are used for evaluating regional and global heart function, respectively. Measuring global function parameters directly from tMRI is challenging due to the obstruction of the anatomical structure by the tagging pattern. The purpose of this study was to develop a method for processing the tMRI images to improve the myocardium-blood contrast in order to estimate global function parameters from the processed images.

Materials and methods

The developed method consists of two stages: (1) removing the tagging pattern based on analyzing and modeling the signal distribution in the image’s k-space, and (2) enhancing the blood-myocardium contrast based on analyzing the signal intensity variability in the two tissues. The developed method is implemented on images from twelve human subjects.

Results

Ventricular mass measured with the developed method showed good agreement with that measured from gold-standard cMRI images. Further, preliminary results on measuring ventricular volume using the developed method are presented.

Conclusion

The promising results in this study show the potential of the developed method for evaluating both regional and global heart function from a single set of tMRI images, with associated reduction in scan time and patient discomfort.

     

Is there a place for virtual reality simulators in assessment of competency in percutaneous renal access?

Objective

To assess competency of urology post-graduate trainees (PGTs) in percutaneous renal access (PCA).

Methods

Upon obtaining ethics approval and informed consents, PGTs between post-graduate years (PGY-3 to PGY-5) from all four urology programs in Québec were recruited. PCA competency of each participant was assessed objectively by performing task 4 on the PERC Mentor? simulator, where they had to correctly access and pop 7 balloons in 7 different renal calyces and subjectively by the validated Percutaneous Nephrolithotomy—Global Rating Scale (PCNL-GRS).

Results

A total of 26 PGTs with a mean age of 29.2 ± 0.7 years participated in this study. When compared with the 21 PGTs without practice, all 5 PGTs who had practiced on the simulator were competent (p = 0.03), performed the task with significantly shorter operative time (13.9 ± 0.7 vs. 4.4 ± 0.4 min; p < 0.001) and fluoroscopy time (9.3 ± 0.6 vs. 3.4 ± 0.4 min; p < 0.001), and had significantly higher PCNL-GRS scores (13 ± 0.6 vs. 20.6 ± 1; p < 0.001) and successful attempts to access renal calyces (23 ± 5 vs. 68.7 ± 11; p = 0.001). According to a pass score of 13/25, thirteen PGTs were competent. Competent PGTs performed the task with significantly shorter fluoroscopy time (9.8 vs. 6.5 min; p = 0.01) and higher percentage of successful attempts to access renal calyces (p < 0.001), higher PCNL-GRS scores (p < 0.001), and lower complications (p = 0.01).

Conclusion

The PCNL-GRS in combination with the PERC Mentor? simulator was able to differentiate between competent and non-competent PGTs.

     

Interleukin-3 treatment of rhesus monkeys leads to increased production of histamine-releasing cells that express interleukin-3 receptors at high levels

To understand the hematopoietic and nonhematopoietic responses to interleukin-3 (IL-3), expression of cell-surface IL-3 receptors (IL-3R) was examined on bone marrow (BM) cells and peripheral blood (PB) cells of rhesus monkeys during the course of in vivo IL-3 treatment. Whereas IL-3R expression is low in untreated monkeys, IL-3 administration led to a gradual increase in both low- and high-affinity binding sites for IL-3. This increase reflected the total number of cells expressing IL- 3Rs, as detected by flow cytometry using biotinylated IL-3. Most of these IL-3R+ cells in both BM and PB could be characterized as basophilic granulocytes that contained high levels of histamine. In contrast to the effect on these differentiated cells, IL-3 administration did not significantly alter the low level IL-3R expression on immature, CD34+ cells. Further flow cytometric analysis using biotinylated growth factors showed that the IL-3R+ basophils also expressed receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF), but not for IL-6 or Kit ligand. These findings indicated that the IL-3R+ cells included neither monocytes, which express GM-CSFRs and IL-6Rs abundantly, nor mast cells, which express c- kit. By combining flow cytometric and Scatchard data, it was calculated that the basophils contain as many as 1 to 2 x 10(3) high-affinity IL- 3Rs and 15 to 30 x 10(3) low-affinity sites. The finding that in vivo IL-3 treatment leads to the production of large numbers of cells that express high levels of IL-3R and are capable of producing histamine provides an explanation for the often severe allergic reactions that occur during prolonged IL-3 administration. It also indicates that IL- 3, in addition to its direct effects on hematopoietic cells, may also stimulate hematopoiesis through the release of secondary mediators such as histamine by IL-3-responsive mature cells.     

Protonation states of membrane-embedded carboxylic acid groups in rhodopsin and metarhodopsin II: a Fourier-transform infrared spectroscopy study of site-directed mutants.

A method was developed to measure Fourier-transform infrared (FTIR) difference spectra of detergent-solubilized rhodopsin expressed in COS cells. Experiments were performed on native bovine rhodopsin, rhodopsin expressed in COS cells, and three expressed rhodopsin mutants with amino acid replacements of membrane-embedded carboxylic acid groups: Asp-83-->Asn (D83N), Glu-122-->Gln (E122Q), and the double mutant D83N/E122Q. Each of the mutant opsins bound 11-cis-retinal to yield a visible light-absorbing pigment. Upon illumination, each of the mutant pigments formed a metarhodopsin II-like species with maximal absorption at 380 nm that was able to activate guanine nucleotide exchange by transducin. Rhodopsin versus metarhodopsin II-like photoproduct FTIR-difference spectra were recorded for each sample. The COS-cell rhodopsin and mutant difference spectra showed close correspondence to that of rhodopsin from disc membranes. Difference bands (rhodopsin/metarhodopsin II) at 1767/1750 cm-1 and at 1734/1745 cm-1 were absent from the spectra of mutants D83N and E122Q, respectively. Both bands were absent from the spectrum of the double mutant D83N/E122Q. These results show that Asp-83 and Glu-122 are protonated both in rhodopsin and in metarhodopsin II, in agreement with the isotope effects observed in spectra measured in 2H2O. A photoproduct band at 1712 cm-1 was not affected by either single or double replacements at positions 83 and 122. We deduce that the 1712 cm-1 band arises from the protonation of Glu-113 in metarhodopsin II.     

Antifungal and Antihepatotoxic Effects of Sepia Ink Extract Against Oxidative Stress as a Risk Factor of Invasive Pulmonary Aspergillosis in Neutropenic Mice

Background

There is a great need for novel strategies to overcome the high mortality associated with invasive pulmonary aspergillosis (IPA) in immunocompromised patients. To evaluate the antifungal and antihepatotoxic potentials of Sepia ink extract, its effect on liver oxidative stress levels was analyzed against IPA in neutropenic mice using amphotercin B as a reference drug.

Materials and Methods

Eighty neutropenic infected mice were randomly assigned into four main groups. The 1^st group was treated with saline, neutropenic infected (NI), the 2^nd group was treated with ink extract (200 mg/kg) (IE) and the 3^rd group was treated with amphotericin B (150 mg/kg) (AMB) and 4^th group was treated with IE plus AMB. Treatment was started at 24 h after fungal inoculation (1×10⁹ conidia/ml).

Results

The present study revealed good in vitro and in vivo antifungal activity of IE against A. fumigatus. IE significantly reduced hepatic fungal burden and returns liver function and histology to normal levels. Compared with the untreated infected group, mice in the IE, AMB, and IE+ AMB groups had increased glutathione reduced (GSH) and superoxide dismutase (SOD) and significantly reduced malondialdehyde (MDA) levels at 24 and 72 h after inoculation with A. fumigatus conidia.

Conclusion

It is then concluded that in combination with antifungal therapy (AMB), IE treatment can reduce hepatic fungal burden, alleviate hepatic granulomatous lesions and oxidative stress associated with IPA in neutropenic mice