Diagnosis of Bartonella endocarditis by a real-time nested PCR assay using serum

Bartonella endocarditis is a severe disease for which blood cultures frequently remain negative. We tested three PCR assays by using specimens of serum sampled early during the disease from 43 patients diagnosed in our laboratory as having Bartonella endocarditis on the basis of serological, culture, and/or valvular molecular detection. We tested a two-step nested PCR (TSN-PCR), a one-step nested PCR (OSN-PCR) with a regular thermal cycler, and a one-step nested PCR with the LightCycler (LCN-PCR). These assays were performed with primers derived from the riboflavin synthase-encoding gene ribC, never before amplified in our laboratory. Due to contamination of negative controls, the results of the TSN-PCR were not interpretable, and this technique was no longer considered. The LCN-PCR had a specificity of 100% and a sensitivity of 58.1%, higher than those of the OSN-PCR (18.6%; P < 0.01) and prolonged blood culturing (7.1%; P < 0.01). The LCN-PCR results correlated strictly with those of other direct diagnostic tests, when available, and identified the causative species for six patients previously diagnosed on the basis of serological analysis only. The efficacy of the LCN-PCR was not influenced by antibiotics (P = 0.96) but was altered by prolonged storage of serum specimens at -20 degrees C (P = 0.04). Overall, the LCN-PCR is specific and more sensitive than traditional methods (i.e., culturing and/or PCR with EDTA-treated blood). It can easily be applied to the diagnosis of patients with suspected Bartonella endocarditis, especially when only serum is available.     

In vitro and in vivo antitumor effects of bisphosphonates

Bisphosphonates are powerful inhibitors of osteoclast-mediated bone resorption. They are currently used in the palliative treatment of bone metastases. However, bisphosphonates do not only act on osteoclasts. There is now extensive in vitro preclinical evidence that bisphosphonates can act on tumor cells: they inhibit tumor cell adhesion to mineralized bone as well as tumor cell invasion and proliferation. Bisphosphonates induce also tumor cell apoptosis and stimulate gammadelta T cell cytotoxicity against tumor cells. In vivo, bisphosphonates inhibit bone metastasis formation and reduce skeletal tumor burden. This may reflect direct antitumor effects and indirect effects via inhibition of bone resorption. In addition, bisphosphonates inhibit experimental angiogenesis in vitro and in vivo. Understanding the molecular mechanisms through which bisphosphonates act on tumor and endothelial cells will be undoubtedly an important task in the future. It will allow the design of clinical trials to investigate whether the antitumor activity of bisphosphonates can be realized in the clinical setting.     

Transposition of an American-designed comprehensive medical student examination within the framework of the forthcoming French nationwide comprehensive examination. A preliminary study

Medical training is undergoing extensive revision in France. A nationwide comprehensive clinical competency examination will be administered for the first time in 2004, relying exclusively on essay-questions. Unfortunately, these questions have psychometric shortcomings, particularly their typically low reliability. High score reliability is mandatory in a high-stakes context. The National Board of Medical Examiners-designed multiple choice-questions (MCQ) are well adapted to assess clinical competency with a high reliability score. The purpose of this study was to test the hypothesis that French medical students could take an American-designed and French-adapted comprehensive clinical knowledge examination with this MCQ format. Two hundred and eighty five French students, from four Medical Schools across France, took an examination composed of 200 MCQs under standardized conditions. Their scores were compared with those of American students. This examination was found assess French students' clinical knowledge with a high level of reliability. French students' scores were slightly lower than those of American students, mostly due to a lack of familiarity with this particular item format, and a lower motivational level. Another study is being designed, with a larger group, to address some of the shortcomings of the initial study. If these preliminary results are replicated, the MCQ format might be a more defendable and sensible alternative to the proposed essay questions.     

Randomized trials in the prevention of recurrent calcium oxalate stones

Kidney stone, with or without lumbar pain, is a major health care problem because of its prevalence and cost for both the patient and the society. Although, surgical procedures are well known, medical treatment and recurrences prophylaxis are uncodified. Fifteen stone recurrence prevention studies have been reviewed, evaluating dietary intake and drugs. The most important factor is a daily diuresis of at least 2 liters. Calcium intake shouldn't be restricted, whereas oxalate, sodium, and protein intakes have to be limited. Hyper and normocalciuretic kidney stone formers improve their outcome with thiazide or indapamide treatment. Hyperuricosuria justifies allopurinol. Potassium citrate (without sodium) may decrease recurrence risk, even in patients without hypocitraturia.     

Radiation-induced DNA damage and repair in lymphocytes from breast cancer patients and their correlation with acute skin reactions to radiotherapy

PURPOSE: Repair of radiation-induced DNA damage plays a critical role for both the susceptibility of patients to side effects after radiotherapy and their subsequent cancer risk. The study objective was to evaluate whether DNA repair data determined in vitro are correlated with the occurrence of acute side effects during radiotherapy. METHODS AND MATERIALS: Breast cancer patients receiving radiation therapy after a breast-conserving surgery were recruited in a prospective epidemiologic study. As an indicator for clinical radiosensitivity, adverse reactions of the skin were recorded. Cryo-preserved lymphocytes from 113 study participants were gamma-irradiated with 5 Gy in vitro and analyzed using the alkaline comet assay. Reproducibility of the assay was determined by repeated analysis (n = 26) of cells from a healthy donor. A coefficient of variation of 0.3 was calculated. RESULTS: The various parameters determined to characterize the individual DNA repair capacity showed large differences between patients. Eleven patients were identified with considerably enhanced DNA damage induction, and 7 patients exhibited severely reduced DNA repair capacity after 15 and 30 min. Six patients were considered as clinically radiosensitive, indicated by moist desquamation of the skin after a total radiation dose of about 50 Gy. CONCLUSIONS: Using the alkaline comet assay as described here, breast cancer patients were identified showing abnormal cellular radiation effects, but this repair deficiency corresponded only at a very limited extent to the acute radiation sensitivity of the skin. Because impaired DNA repair could be involved in the development of late irradiation effects, individuals exhibiting severely reduced DNA repair capacity should be followed for the development of late clinical symptoms.     

MRI definition of target volumes using fuzzy logic method for three-dimensional conformal radiation therapy

PURPOSE: Three-dimensional (3D) volume determination is one of the most important problems in conformal radiation therapy. Techniques of volume determination from tomographic medical imaging are usually based on two-dimensional (2D) contour definition with the result dependent on the segmentation method used, as well as on the user's manual procedure. The goal of this work is to describe and evaluate a new method that reduces the inaccuracies generally observed in the 2D contour definition and 3D volume reconstruction process. METHODS AND MATERIALS: This new method has been developed by integrating the fuzziness in the 3D volume definition. It first defines semiautomatically a minimal 2D contour on each slice that definitely contains the volume and a maximal 2D contour that definitely does not contain the volume. The fuzziness region in between is processed using possibility functions in possibility theory. A volume of voxels, including the membership degree to the target volume, is then created on each slice axis, taking into account the slice position and slice profile. A resulting fuzzy volume is obtained after data fusion between multiorientation slices. Different studies have been designed to evaluate and compare this new method of target volume reconstruction and a classical reconstruction method. First, target definition accuracy and robustness were studied on phantom targets. Second, intra- and interobserver variations were studied on radiosurgery clinical cases. RESULTS: The absolute volume errors are less than or equal to 1.5% for phantom volumes calculated by the fuzzy logic method, whereas the values obtained with the classical method are much larger than the actual volumes (absolute volume errors up to 72%). With increasing MRI slice thickness (1 mm to 8 mm), the phantom volumes calculated by the classical method are increasing exponentially with a maximum absolute error up to 300%. In contrast, the absolute volume errors are less than 12% for phantom volumes calculated by the fuzzy logic method. On radiosurgery clinical cases, target volumes defined by the fuzzy logic method are about half of the size of volumes defined by the classical method. Also, intra- and interobserver variations slightly decrease with the fuzzy logic method, resulting in the definition of a better common volume fraction. CONCLUSION: Our fuzzy logic method shows accurate, robust, and reproducible results on phantoms and clinical targets imaged on MRI.