Reproductibilité en scintigraphie osseuse planaire,TEMP et TEMP/TDM du pied douloureux : importance d’une sémiologie standardisée

AimThe diagnostic benefit of bone single photon emission computed tomography/computed tomography (SPECT/CT) is currently being demonstrated. However, until now, reproducibility has been poorly investigated. Therefore, a study was undertaken to assess intra- and inter-reader reliability comparing bone planar views, SPECT and SPECT/CT.MethodsThe study was carried out on a cohort of 50 adults consecutively referred to two distinct Nuclear Medicine departments for clinical and radiological suspicion of a reflex sympathetic dystrophy (RSD) of the foot. Each set of planar views and SPECT/CT was independently re-read by two Nuclear Medicine physicians (one junior and one senior expert) in a blinded fashion. An array of bone scan and CT semiological criteria depicting RSD and main differential diagnoses was initially elaborated. Reliability was measured by percentage of agreement and computation of unweighted kappa.ResultsAmong the 50 patients, only four actually suffered from RSD. Among the 46 patients who did not suffer from RSD, 28 were affected by miscellaneous skeletal lesions. This is the reason why the study shifted from focusing on RSD to the etiologic diagnosis of a painful foot. Percentage of inter-reader agreement rose from 74% for planar scintigraphy and SPECT to 96% for SPECT/CT. This study showed reliability indices higher than in literature mainly due to the use of predefined detailed semiological criteria and to the learning effect of the junior physician at senior physician school.ConclusionBone SPECT/CT provides significantly stronger intra-reader and inter-reader agreement in comparison to planar images and stand-alone SPECT.     

Problème diagnostique posé par une lésion hépatique hypermétabolique en TEP à la fluorocholine (18F) : à propos d’un cas

IntroductionWe report a case of atypical fluorocholine (18F) PET/CT hypermetabolic hepatic lesion discovered during the staging of a prostate carcinoma.Case reportBecause of elevated PSA serum level, the patient had prostate biopsies which elicited an adenocarcinoma with a Gleason score of 8 (4 + 4). Pelvic MRI did not display any extracapsular disease extension. The PET/CT scan demonstrated a prostatic focal uptake and a liver increased uptake area matching with a segment VII hepatic nodule measuring 25 mm within a fatty liver, which was hypometabolic on the PET scan and hypodense on the CT scan. The liver ultrasound study reported the lesion as a focal spared area of healthy liver tissue within steatosis, whereas MRI diagnostic conclusion was inflammatory hepatocellular adenoma. When asking the patient, it appeared that the hepatic nodule had been known for 7 years, its size was unchanged, and, from previous radiologic imaging, it had been considered as an adenoma. However, there was no histological proof.DiscussionIn the interpretation of the PET/CT scan findings, we excluded a hepatocellular carcinoma and a prostate metastasis due to the long period of time during which the nodule had been followed up without significant change. We thought that focal nodular hyperplasia, which is fluorocholine avid, was the most likely diagnosis, knowing that hepatocellular adenomas, including the inflammatory type, have not been reported to display increased fluorocholine uptake. We noticed that the patient's fatty liver uptake was low, which could have accounted for a falsely increased uptake by the nodule. But, similarly to other authors, we could not find any relationship between CT density and fluorocholine uptake.ConclusionThis case shows a discrepancy between the radiologic and nuclear medicine findings. However, this hepatic nodule is likely to be benign because of the lesion characteristics and the patient medical history.     

Influence of shape-memory stent grafts on local aortic compliance

The effect of repair techniques on the biomechanics of the aorta is poorly understood, resulting in significant levels of postoperative complications for patients worldwide. This study presents a computational analysis of the influence of Nitinol-based devices on the biomechanical performance of a healthy patient-specific human aorta. Simulations reveal that Nitinol stent-grafts stretch the artery wall so that collagen is stretched to a straightened high-stiffness configuration. The high-compliance regime (HCR) associated with low diastolic lumen pressure is eliminated, and the artery operates in a low-compliance regime (LCR) throughout the entire cardiac cycle. The slope of the lumen pressure–area curve for the LCR post-implantation is almost identical to that of the native vessel during systole. This negligible change from the native LCR slope occurs because the stent-graft increases its diameter from the crimped configuration during deployment so that it reaches a low-stiffness unloading plateau. The effective radial stiffness of the implant along this unloading plateau is negligible compared to the stiffness of the artery wall. Provided the Nitinol device unloads sufficiently during deployment to the unloading plateau, the degree of oversizing has a negligible effect on the pressure–area response of the vessel, as each device exerts approximately the same radial force, the slope of which is negligible compared to the LCR slope of the native artery. We show that 10% oversizing based on the observed diastolic diameter in the mid descending thoracic aorta results in a complete loss of contact between the device and the wall during systole, which could lead to an endoleak and stent migration. 20% oversizing reaches the Dacron enforced area limit (DEAL) during the pulse pressure and results in an effective zero-compliance in the later portion of systole.

     

A Plasmodium falciparum copper-binding membrane protein with copper transport motifs

Formerly known as a hypoendemic malaria country, the Republic of Djibouti declared the goal of pre-eliminating malaria in 2006. The aim of the present study was to evaluate the prevalence of Plasmodium falciparum, Plasmodium vivax and mixed infections in the Djiboutian population by using serological tools and to identify potential determinants of the disease and hotspots of malaria transmission within the country. The prevalence of P. falciparum and P. vivax within the districts of the capital city and the rest of the Republic of Djibouti were assessed using 13 and 2 serological markers, respectively. The relationship between the immune humeral response to P. falciparum and P. vivax and variables such as age, gender, wealth status, urbanism, educational level, distance to rivers/lakes, living area, having fever in the last month, and staying in a malaria-endemic country more than one year was estimated and analysed by questionnaires administered to 1910 Djiboutians. Multivariate ordinal logistic regression models of the immune humeral response were obtained for P. falciparum and P. vivax. The P. falciparum and P. vivax seroprevalence rates were 31.5%, CI95% [29.4-33.7] and 17.5%, CI95% [15.8-19.3], respectively. Protective effects against P. falciparum and P. vivax were female gender, educational level, and never having visited a malaria-endemic area for more than one year. For P. falciparum only, a protective effect was observed for not having a fever in the last month, living more than 1.5 km away from lakes and rivers, and younger ages. This is the first study that assessed the seroprevalence of P. vivax in the Republic of Djibouti. It is necessary to improve knowledge of this pathogen in order to create an effective elimination programme. As supported by recent observations on the subject, the Republic of Djibouti has probably demonstrated a real decrease in the transmission of P. falciparum in the past seven years, which should encourage authorities to improve efforts toward elimination.     

The effect of fermentation on the growth and survival ofSalmonella typhimurium,Staphylococcus aureus,Bacillus cereus andPseudomonas aeruginosa in fermenting tef (Eragrostis tef)

Summary Growth ofSalmonella typhimurium, Staphylococcus aureus, Bacillus cereus andPseudomonas aeruginosa was inhibited when the pH of fermenting tef approached 5.0, 5.0, 5.5 and 5.0, respectively. However the test organisms grew in far more acidic conditions in broth than in fermenting tef and this is due to antimicrobial substance(s) being produced by some of the lactic acid bacteria. Except forBacillus cereus spores, all the test organisms were heat-inactivated during the baking process of the final tef injera.

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Effet de la fermentation sur la croissance et la survie de Salmonella typhimurium, Staphylococcus aureus, Bacillus cereus et Pseudomonas aeruginosa dans le tef (Eragrostis tef) en fermentation

Résumé La croissance deSalmonella typhimurium, deStaphylococcus aureus, deBacillus cereus et dePseudomonas aeruginosa est inhibée lorsque les pH du tef en fermentation approchent respectivement 5:0, 5.0, 5.5 et 5.0. Toutefois, les organismes tests croissent dans des conditiones bien plus acides que dans le tef en fermentation. Ceci est dû à des substances antimicrobiennes produites par certaines bactéries lactiques. A l'exception des spores deBacillus cereus, tous les organismes tests sont inactivés par la chaleur durant le processus de cuisson.

     

Short-term effects of Al3+ on the osmotic behavior of red beet (Beta vulgaris L.) protoplasts

The short-term (less than 10 min) effects of Al³⁺ on the biophysical properties of plasma membranes were investigated by time-series image analysis of osmotically-induced volumetric and morphologic changes of red beet (Beta vulgaris L.) protoplasts. Exposure to Al³⁺ under hypotonic conditions reduced the volumetric expansion of protoplasts and their resultant burst: i.e. lysis of protoplasts in a concentration-dependent manner. Under hypertonic conditions, protoplasts exposed to Al³⁺ underwent an enhanced volumetric contraction in cross-sectional area, while maintaining higher protoplast roundness. The residual effects of Al³⁺ pre-treatment on subsequent osmotic behavior were also examined, and protoplasts pre-treated with Al³⁺ also exhibited less lysis during subsequent exposure to hypotonic conditions and enhanced volumetric contractions and higher roundness under subsequent hypertonic conditions. Under our experimental conditions, Al³⁺ consistently minimized protoplast surface area by inhibiting osmotic expansion or by enhancing osmotic contraction, as well as by maintaining higher protoplast roundness. These results suggested that the electrostatic property of Al³⁺ might have induced the binding and possible cross-linking of negatively-charged sites on the plasma membrane surface. This may be an important factor in understanding the mechanism of Al³⁺ phytotoxicity.     

Fungal virulence studies come of age

Sophisticated molecular biological research has revealed many virulence attributes in at least four pathogenic fungi, but the future study of fungal virulence requires investigators to distinguish between molecules that directly interact with the host, molecules that regulate these, and molecules that are always required for fungal growth and survival, independent of the host.     

Differential phosphorylation of PKR associates with deregulation of eIF-2α phosphorylation and altered growth characteristics in 3T3-F442A fibroblasts

Murine embryonic 3T3-F442A fibroblasts contain elevated levels of a factor (dRF) inhibitory to the phosphorylation of PKR, when cultured under differentiation restrictive (10% cat serum) as compared to permissive conditions (10% fetal bovine serum). Experiments were conducted with the objective of understanding the effect of altered PKR activity on the growth characteristics of 3T3-F442A fibroblasts. Analysis of the phosphoprotein pattern confirmed that the phosphorylation of PKR was reduced in cells cultured in cat serum during specific stages of growth. In a similar manner, evaluation of eIF-2 phosphorylation by vertical slab gel iso-electric focusing indicated that inactivation of PKR correlated with reduction of eIF-2 phosphorylation. The expression of PKR was confirmed by western blotting ruling out the possibility of diminished protein as the cause of loss of activity. In addition, the expression of dRF coincided with the inactivation of PKR as shown by immunoblotting and phosphorylation studies. The reduction in PKR activity and subsequent deregulation of eIF-2 phosphorylation was related to appearance of tumor-like cellular morphology and increased cell density as shown by cell counts and [³H]-thymidine uptake. Taken together, these results support a hypothesis that PKR functions to regulate the growth of 3T3-F442A cells. Furthermore, our findings raise the possibility that deregulation of PKR by endogenous inhibitory molecules, such as dRF, may alter normal growth and differentiation. Such a deregulation of PKR may also contribute to the proliferation of tumor cells.