Design of an isolated pig heart preparation for positron emission tomography and magnetic resonance imaging

RATIONALE AND OBJECTIVES: Validation of new positron emission tomography (PET) tracers or magnetic (MR) imaging contrast agents is based on isolated rodent heart preparations. The use of larger animals could provide a more direct validation using the devices used for humans. METHODS: An isolated pig heart preparation has been developed and adapted to the technical constraints of whole body PET and MR imaging. This preparation could be used either in the Langendorff or working mode after selective cannulation of both coronary arteries. RESULTS: The authors showed that quantification of regional kinetics of PET tracers was possible using this preparation by measuring fluorine-18-labeled deoxyglycose (18FDG) kinetics in remote and ischemic territories. Experiments using MR imaging contrast agents, for myocardial perfusion, demonstrated the ability of this preparation to accurately validate these contrast agents over a wide range of flow rates. CONCLUSIONS: An isolated pig heart preparation could be developed to fulfill the constraints of PET and MR imaging, and proved useful for the study of the distribution of different tracers or contrast media developed for functional cardiac imaging in humans.     

The In Vivo Radiosensitizing Effect of Gold Nanoparticles Based MRI Contrast Agents

Owing to the high atomic number (Z) of gold element, the gold nanoparticles appear as very promising radiosensitizing agents. This character can be exploited for improving the selectivity of radiotherapy. However, such an improvement is possible only if irradiation is performed when the gold content is high in the tumor and low in the surrounding healthy tissue. As a result, the beneficial action of irradiation (the eradication of the tumor) should occur while the deleterious side effects of radiotherapy should be limited by sparing the healthy tissue. The location of the radiosensitizers is therefore required to initiate the radiotherapy. Designing gold nanoparticles for monitoring their distribution by magnetic resonance imaging (MRI) is an asset due to the high resolution of MRI which permits the accurate location of particles and therefore the determination of the optimal time for the irradiation. We recently demonstrated that ultrasmall gold nanoparticles coated by gadolinium chelates (Au@DTDTPA‐Gd) can be followed up by MRI after intravenous injection. Herein, Au@DTDTPA and Au@DTDTPA‐Gd were prepared in order to evaluate their potential for radiosensitization. Comet assays and in vivo experiments suggest that these particles appear well suited for improving the selectivity of the radiotherapy. The dose which is used for inducing similar levels of DNA alteration is divided by two when cells are incubated with the gold nanoparticles prior to the irradiation. Moreover, the increase in the lifespan of tumor bearing rats is more important when the irradiation is performed after the injection of the gold nanoparticles. In the case of treatment of rats with a brain tumor (9L gliosarcoma, a radio‐resistant tumor in a radiosensitive organ), the delay between the intravenous injection and the irradiation was determined by MRI.     

Detection of Chlamydia trachomatis infection by PCR in first voided urines in men

The goal of this study was to evaluate whether the new commercially available PCR-based assay Amplicor C. trachomatis (Roche Molecular Systems) could improve the diagnosis of chlamydial urogenital infections in men, compared with cell culture of C. trachomatis considered as the reference method. A total of 466 men attending the STD clinic were tested by the Amplicor test in urine and by cell culture in urethra. The prevalence of C. trachomatis was 13.7% (64/466) by cell culture and 14.4% (67/466) by the Amplicor test. After resolution of the discrepant results, the sensitivity of culture was 91.4% in male urethral specimens. The resolved sensitivity of the PCR assay was 92.7% in male urine and the specificity was 99.5%. We concluded that this rapid PCR-based assay showed an improvement in quality for diagnosing C. trachomatis infections in men.     

Balanitis and infectious agents. A prospective study of 100 cases

INTRODUCTION: The aim of this study was: 1) to evaluate the rate of micro-organism isolation in 100 patients consulting for balanitis at the Centre of sexually transmitted diseases at the St. Louis Hospital in Paris in comparison with that of micro-organisms isolated in 60 men without balanitis; 2) to search for a possible correlation between the clinical aspect of the disease and the nature of the infectious agent identified. METHODS: One hundred consecutive patients were included in the study. All underwent a clinical examination and samples were taken for bacteriology, mycology and virology examinations. Sixty healthy volunteers served as controls. Two samples were taken from the balanopreputial groove in search for fungi and bacteria. RESULTS: Candida albicans (CA) was isolated in 33 p. 100 of the patients. A pathogenic bacteria (beta-haemolytic streptococci, Staphylococcus aureus, Klebsiella), or a potentially pathogenic germ (Haemophilus parainfluenzae, anaerobic bacteria, Gardnerella vaginalis, Streptococcus milleri, group HB5) was found without CA in 28 p. 100 of the cases, a commensal flora (enterobacteria, group D streptococci) was found without CA in 8 p. 100 and in 31 p. 100 of the cases non causal agent could be identified. DISCUSSION: This series confirms the non-pathogenic nature of commensal bacteria: the number of isolations was similar in the subjects with and without balanitis (p < 0.9). The role played by the other bacteria in the development of balanitis is discussed: saprophytic association or direct pathogenesis? The significant difference in the rate of bacteria isolations in patients with balanitis compared with controls (p < 0.001) is in favour of a pathogenic role. The clinical presentation was not predictive of the presence of any particular micro-organism excepting the presence of pustules which were highly suggestive of candidiasis.     

A multimodal corpus of simulated consultations between a patient and multiple healthcare professionals

Language resources for studying doctor–patient interaction are rare, primarily due to the ethical issues related to recording real medical consultations. Rarer still are resources that involve more than one healthcare professional in consultation with a patient, despite many chronic conditions requiring multiple areas of expertise for effective treatment. In this paper, we present the design, construction and output of the Patient Consultation Corpus, a multimodal corpus of simulated consultations between a patient portrayed by an actor, and at least two healthcare professionals with different areas of expertise. As well as the transcribed text from each consultation, the corpus also contains audio and video where for each consultation: the audio consists of individual tracks for each participant, allowing for clear identification of speakers; the video consists of two framings for each participant—upper-body and face—allowing for close analysis of behaviours and gestures. Having presented the design and construction of the corpus, we then go on to briefly describe how the multi-modal nature of the corpus allows it to be analysed from several different perspectives.

     

Adaptive and self-evaluating registration method for myocardial perfusion assessment

With the advent of ultra-fast MR I, it is now possible to assess non-invasively regional myocardial perfusion with multislice coverage and sub-second temporal resolution. First-pass contrast enhanced studies are acquired with ECG-triggering and breath holding. Nevertheless, some respiratory induced movements still remain. Myocardial perfusion can be assessed locally byparametric imaging methods such as Factor Analysis of Medical Image Sequences (FAMIS), provided that residual motion can be corrected. An a posteriori registration method implemented in the image domain is proposed. It is based on an adaptive registration model of the heart combining three elementary shapes (left ventricle, right ventricle and pericardium). The registration procedure is performed on a potential map derived from the distance map. To evaluate the quality of the registration procedure a superimposition score between the registration model and the contour automatically extracted in the sequence is proposed. Rigid transformation hypotheses and registration analysis provide an efficient and automatic method which allows the rejection of outlier images, such as; outof synchronisation images, out of plane acquisitions. When compared to a manual registration method, this approach reduces processing time and requires a minimal intervention from the operator. The proposed method performs registration with a subpixel accuracy. It has been successfully applied to simulated images and clinical data. It should facilitate the use of MR first-pass perfusion studies in clinical practice.