Atomic-scale structure of biogenic materials by total X-ray diffraction: a study of bacterial and fungal MnOx.

Biogenic materials are produced by microorganisms and are typically found in a nanophase state. As such, they are difficult to characterize structurally. In this report, we demonstrate how high-energy X-ray diffraction and atomic pair distribution function analysis can be used to determine the atomic-scale structures of MnO(x) produced by bacteria and fungi. These structures are well-defined, periodic, and species-specific, built of Mn-O(6) octahedra forming birnessite-type layers and todorokite-type tunnels, respectively. The inherent structural diversity of biogenic material may offer opportunities for practical applications.

[Stop smoking help: keys to long term success]. / L'aide a l'arrêt du tabagisme: la réussite au long terme. Aspects psychologiques et pharmacologiques.

This review deals with the pharmacological and psychological means to help in smoking cessation and compares the efficacy of the different methods. Pharmacological support results in a smoking cessation rate reaching at best 20-25%. The efficacy of behavioural and cognitive therapy have been much less validated so far. Multidisciplinary specialized centres for helping smokers have been raised under the care of FARES in the French Community of Belgium.

[The therapeutic impact of PET-FDG scanning in broncho-pulmonary cancer]. / Impact thérapeutique de l'imagerie TEP-FDG en carcinologie bronchopulmonaire.

BACKGROUND: Because of the expected high performances of scintigraphic scans with [18F]-fluorodeoxyglucose (FDG) not only in diagnostics and but also in therapeutic impact, especially in thoracic oncology, there are a lot of French nuclear medicine departments which will soon be equipped with a positron emission tomograph (PET). MATERIAL AND METHODS: The Nuclear Medicine Department of the Hôpital d'Instructions des Armées du Val-de-Grâce, Paris, led a retrospective study among physicians interested in 338 FDG-PET exams performed between may 2000 and march 2002 in order to compare its own results with international literature concerning four indications for lung cancer: pulmonary nodule or mass malignancy diagnostic, lung carcinoma extension evaluation, therapeutic efficiency, recurrence suspicion. RESULTS: There seems to be no divergence, regarding limitation induced by the not exhaustive analysis of the retrospective study: more than every two FDG-PET exam highly influenced the effective therapy. CONCLUSION: That is why clinical FDG-PET has to be widely developed to investigate lung cancer.

[Clinical case of the month. Down syndrome and myxedema. Report of a case and review of the literature]. / Le cas clinique du mois. Syndrome de Down et myxoedéme: description d'un cas et revue de la littérature.

A case of myxedema secondary to undetected hypothyroidism developed in a 48 year old 21-trisomic male. This paper presents a short discussion about different possible diagnoses and a review of the literature concerning the relationship between Down Syndrome and hypothyroidism or other diseases.

[Positron emission tomography in clinical oncology]. / Tomographie par émission de positons en oncologie clinique.

A NEW FORM OF MEDICAL IMAGING: Positron emission tomography (PET) is used for the non-invasive in vivo visualisation of biochemical cell processes. It reveals the metabolic characteristics of neoplastic lesions and hence their identification by compensating the lack of lesion specificity of radiological techniques. VARIOUS INDICATIONS: Using the current oncology marker, 18F-fluorodeoxyglucose (FDG), excellent results with PET have been established at all stages of neoplasia, notably for the diagnosis of initial malignancy and the identification of residual lesions and early detection of relapses. Moreover, the fact that the whole of the body can be explored makes PET the tool of choice in the control of the extension and operability of cancers. With the close correlation between imaging and the metabolism of the lesions, PET is the earliest and most precise for assessing the effects of treatment. LIMITS AND PERSPECTIVES: The existence of benign inflammatory FDG binding should lead to the development of markers of other metabolisms directly linked to cell proliferation. The lack of anatomical reference points characteristic of PET does not permit the precise localisation of the lesions detected and could be corrected by combining, in a single apparatus, the PET camera and an X scan, the anatomical resolution of which is irreplaceable. This type of equipment represents the development of a new branch of medical imaging, oncological imaging.

[Percutaneous tracheotomy: personal contributions to the technique]. / Les trachéotomies percutanées: apports personnels à la technique.

We developed within our service of intensive care a hybrid procedure combining the advantages of the techniques of Caglia and Fantoni. Ventilation downstream from the site of dilatation, thanks to a longer tracheal tube of small diameter, ensures an optimal spirometry and reduces to a minimum the time of apnea. It decreases the risks of per-operational subcutaneous emphysema. A system of camera video assembled on a flexible fibroscope allows a direct vision on television screen. The operator can, constantly, visualise his gesture in one glance, in real time. Such an approach increases the security and the effectiveness of the method. The procedure remains nevertheless simple and does not require a thorough experience in percutaneous dilatational tracheotomy.

Multimodal anatomic, functional, and metabolic brain imaging for tumor resection.

OBJECTIVE: Improvement of neurosurgical techniques with a more detailed description of brain tumors and their functional environment. METHODS: We performed: (1) anatomical magnetic resonance imaging (MRI) for reference, (2) functional sequences dedicated to the adjacent cortical structures (sensorimotor, visual, language paradigms), and (3) thallium 201 cerebral tomoscintigraphy to visualize active tumor invasion. Data were transferred to a workstation for automatic registration. RESULTS: All data were combined into one synthetic image showing the foci of high proliferative activity, which have to be completely resected, and the peritumoral functional structures, which have to be spared in order to minimize postoperative sequelae. This trimodal image is entered into a surgical neuronavigation computer for preoperative planning in order to outline tumoral target and functional risk areas. All this information is displayed in the operative microscope (Zeiss MKM) optically linked to MR images. This multimodality technique diminishes operative time by reducing electrocorticography and improves the operative short-term outcome. CONCLUSION: Multimodal imaging is useful for optimization of neurosurgical tumor resection.

[Interest in 18-FDG positron emission tomography in radiotherapy planning: example of lung cancer radiotherapy]. / Intérêt de la tomographie à émission de positons au 18fluoro-déoxy-glucose dans la définition des champs de radiothérapie: exemple de la radiothérapie thoracique.

18 FDG positon emission tomography provides metabolic images and allows better local and metastatic staging than radiologic methods. A best cartography of node involvement and a best delineation of the tumor zone should allow an optimal radiotherapy. Lung cancer is a good example of the interest of this new method.

[Positron emission tomography in head and neck oncology: five cases]. / La tomographie à émission de positons en oncologie ORL. Une revue à propos de 5 cas.

FDG-PET (18-fluoro-desoxyglucose positron emission tomography) is a fonctionnal imaging method based on the high rate of glycolysis in different types of cancer-cells. We report the first five cases where FDG-PET was used in France for head and neck cancers. The results were analyzed on the basis of data reported to date in the literature, leading to a proposal for rational use of this diagnostic available in only a few centers in France. For primary assessment of cervicofacial carcinomas, different imaging techniques such as CT and MRI have improved tumor staging. Although 18-FDG-PET cannot replace these techniques used to monitor size and structural changes in tumors and lymph nodes, it will be helpful in following their metabolic activity. This diagnostic tool consequently is greatly helpful for detection and post-therapeutic evaluation of head and neck carcinomas and their recurrence. 18-FDG-PET is currently under evaluation as a tool for detecting cervical lymph nodes and early assessment of response to chemotherapy.

Quick X-ray absorption spectroscopy for determining metal speciation in environmental samples.

We present a method for determining the chemical speciation of metals in environmental particles based on Quick-X-ray Absorption Spectroscopy. The approach can be applied to either the extended or the near edge fine structure, and consists in the decomposition of the XAS spectrum of an unknown sample on a reference set of standards' spectra using quadratic linear programming. The analysis accounts for the statistical experimental errors generated during the acquisition of X-ray absorption data, and leads to error estimates on the various fractions determined via a Monte Carlo procedure. An application example is presented for the speciation of inorganic Zn in a contaminated sediment sample.

An EXAFS study of zinc coordination in microbial cells.

Five microbes were isolated from metal amended enrichment cultures derived from the sediments of a lake contaminated by a zinc smelter. Each of these organisms was grown in pure culture in the presence of zinc. Quick Extended X-ray Absorption Fine Structure (QEXAFS) spectroscopy was used to investigate the average coordination environment of the zinc associated with the microbial biomass. Fitting of the first coordination shell of zinc shows that significant differences exist for each microbial species examined. The coordination environment of zinc varies between sulfurs to six-fold nitrogen/oxygen. with two microbial strains showing mixed coordination shells. Further study is required in order to characterize these sites and their locations within the cell.

[Positron emission tomography in head and neck oncology]. / Tomographie par émission de positons en oncologie de la tête et du cou.

Defining a therapeutic strategy in oncology requires a substantial amount of imaging data provided by modern techniques. While the description of the lesions and their environment has become very precise, there remains a certain degree of uncertainty concerning tissue typing. Positron emission tomography is a scintigraphy technique which can produce quantitative images of metabolic characteristics. 18F-fluorodeoxyglucose is a tracer allowing an analysis of glucose metabolism known to be highly increased in malignant tissues. Increased uptake is an indication of malignancy with an established correlation with proliferative capacity. The only limitation of the method is the generally weak uptake observed in benign hypermetabolic inflammatory or infectious areas. All stages of the disease are concerned for head and neck cancer patients. Clinical experience to date indicates that PET can be applied most usefully to search or residual disease with a possible differentiation between post-therapeutic fibrosis and viable tumor tissue as well as the identification of early relapse. Study of early response to chemotherapy is also an interesting application. Search for extension can also be improved with this technique allowing both regional and whole body explorations. Positron emission tomography is not widely available in France at the present time so all patients cannot be examined with this technique. Positron emission tomography is an evolving technique with improvements being proposed both in the technique and in tracer elements. Further information will be available with new developments in this non-invasive exploration tool.

[Positron emission tomography in thoracic radiography]. / Apport de la tomographie par émission de positons à la radiothérapie thoracique.

The optimisation of the field of irradiation is the aim of the radiotherapist. Pet-Scan provides information revealing a better cartography of node involvement and allowing a better delineation of the tumour zone. In the follow-up of irradiated patients, PET-Scan provides information on the nature of residual lesions and a possible recurrence.

[Progression of stage I non-seminomatous germ cell tumors during surveillance. Role of positron emission tomography]. / Progression des tumeurs germinales non séminomateuses de stade I sous surveillance. Place de la tomographie à émission de positons.

Surveillance is one of the options proposed in the management of stage 1 non-seminomatous germ cell tumours when there is only a low risk of progression. No consensus has yet been reached concerning the modalities of this surveillance and several protocols are available, including the CCAFU protocol. The presence of recurrences in this population at low risk of progression, estimated to be 5%, accounts for the continuing research for more precise predictive factors of occult metastases. Although several studies appear to indicate a useful predictive value for some of these factors, their application in clinical practice still appears to be difficult. PET metabolic imaging (positron emission tomography) could constitute a new approach to staging of these tumours, allowing the detection of tumour sites by an increase of carbohydrate metabolism of malignant cells. However, no study is yet available to define the real place of this technique.

[Fluorodeoxyglucose and bronchopulmonary cancer. Initial French results with positron emission tomography]. / Fluoro-déoxy-glucose et cancer bronchopulmonaire. Les premiers résultats français en caméra à positons.

Despite recent advances, the contribution of medical imaging techniques is limited, particularly in terms of tissue characterization, in the diagnosis of pulmonary nodules and search for extension of bronchogenic cancer. The metabolic properties of the glucose analog deoxyglucose labeled with 18F1 would allow metabolic imaging. Positron emission tomography (PET) provides clinicians with quality images with an interesting sensitivity. We report the results of a feasibility study conducted in our first 17 patients. We observed 14 true positives, 1 true negative and 1 false positive and 1 false negative in patients with a malignant primary lesion. We analyzed the causes of error. Ten disseminated localizations were identified. Possible developments in terms of therapeutic strategy are discussed. The agreement between our findings and data reported in the literature prompted us to develop a study protocol using 18-fluorodeoxyglucose PET in patients with bronchogenic cancer.

Lung scintigraphy in postpneumonectomy dyspnea due to a right-to-left shunt.

We report the case of a 50-yr-old man who experienced exertional dyspnea 5 mo after a left pneumonectomy for carcinoma. As the clinical features pointed toward a pulmonary embolism, we performed a ventilation plus perfusion radionuclide lung scan. It showed no evidence of pulmonary embolism, but it did show a systemic uptake of the isotope, suggesting a right-to-left shunt that was confirmed by contrast echocardiography, which revealed an atrial septal defect. Right-to-left shunts after pneumonectomy have already been reported and can be diagnosed by lung scintigraphy. Usually, a patent foramen ovale is encountered, but the underlying physiopathology remains under discussion. Clinically, right-to-left shunts are often related to platypnea-orthodeoxia.

[Value of scintigraphy using meta-iodo-benzyl-guanidine (MIBG) in the investigation of cardiac autonomic neuropathy in diabetic patients. Comparison with Ewing tests]. / Apport de la scintigraphie à la méta-iodo-benzyl-guanidine (MIBG) dans l'exploration de la neuropathie végétative cardiaque du diabétique. Comparaison avec les tests d'ewing.

UNLABELLED: Cardiac autonomic neuropathy is a frequent complication of diabetes leading to resting tachycardia, postural hypotension, painless myocardial ischaemia, rhythm disturbances and sudden cardiac death. The aim of the study was to evaluate in a diabetic population the sensitivity of two exploration modes of autonomic neuropathy in diabetics: the Ewing tests which are, at present time, the reference method and the (123-I) meta-iodo-benzyl-guanidine (MIBG) single photon emission computed tomography (SPECT) which evaluates the cardiac sympathetic innervation. PATIENTS AND METHODS: 9 male insulin-dependent diabetes mellitus patients were studied. Mean age was 40.7 +/- 15 years and diabetes duration was 10.8 +/- 6 years. None had hypertension or macroangiography as demonstrated by patient's history, clinical examination, rest and exercise electrocardiography and ambulatory blood pressure monitoring. The complications observed were background retinopathy in 2 patients, incipient nephropathy in 3 and a peripheral neuropathy in 1 patient. Ewing tests, i.e. Valsalva maneuver, beat to beat heart rate variation during deep breathing and standing, blood pressure response to standing and to sustained handgrip, were performed. The results were considered as pathologic when the score was over 2. After injection of 10 mCi (123-I) MIBG, planar images were realized at times 1, 2 and 4 hours and SPECT images after 2 hours. The heart/mediastinum uptake ratio was calculated. RESULTS: We noted abnormalities of planar images in 3 patients, SPECT images in 1, and both in 1 patient. None was positive for Ewing tests. CONCLUSION: Although MIBG SPECT will explore only the sympathetic innervation, these preliminary findings suggest that this technique could be more sensitive for the evaluation of cardiac autonomic neuropathy. Nevertheless cost and lack of disponibility of this technique should limit its use.