ABSTRACT
Cisplatin is one of the most effectively used chemotherapeutic agents for cancer treatment. However, in humans, important cytotoxic side effects are observed including dose-limiting renal damage and profound gastrointestinal symptomatology. The toxic responses to cisplatin in mice are similar to those in human patients. Here, we evaluated whether the acid sphingomyelinase (Asm) mediates at least some of the toxic in vivo effects of cisplatin. To this end, we determined the toxic effects of a single intraperitoneal dose of cisplatin (27 mg/kg) in wild type (Asm(+/+)) and Asm-deficient mice (Asm(-/-)). Tissue injury and apoptosis were determined histologically on hematoxylin-eosin and TUNEL (terminal deoxynucleotidyl transferase (TdT)-mediated nick end labeling) stainings 3, 12, 36 and 72 h after treatment. Our results revealed severe toxicity of cisplatin in Asm(+/+) mice with increased numbers of apoptotic cells in the thymus and small intestine. In marked contrast, Asm(-/-) mice were resistant to cisplatin and no apoptosis was observed in these organs after treatment. Moreover, cisplatin treatment primarily triggered apoptosis of endothelial cells in microvessels of intestine and thymus, an effect that was absent in mice lacking Asm. The data thus suggest that at least some toxic effects of cisplatin are mediated by the Asm in vivo resulting in early death of endothelial cells and consecutive organ damage.
Subject(s)
Antineoplastic Agents/adverse effects , Cisplatin/adverse effects , Cytoprotection/genetics , Gastrointestinal Diseases/chemically induced , Gastrointestinal Tract/drug effects , Sphingomyelin Phosphodiesterase/genetics , Animals , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Apoptosis/genetics , Cisplatin/pharmacology , Cytoprotection/drug effects , Drug Evaluation, Preclinical , Gastrointestinal Diseases/pathology , Gastrointestinal Tract/metabolism , Gastrointestinal Tract/pathology , Genes, p53 , Intestinal Mucosa/drug effects , Intestinal Mucosa/metabolism , Intestinal Mucosa/pathology , Mice , Mice, Knockout , Sphingomyelin Phosphodiesterase/physiologyABSTRACT
Implementation of EURATOM directive 97/43 requires increased scrutiny over the use CT imaging. All CT imaging centers will be required to perform routine QA procedures including measurements of exposure related to frequently performed types of CT examination. CT technologists and radiologists will be required to try and identify ways of decreasing patient exposure for CT examinations while insuring acquisition of diagnostic studies. In turn, this assumes understanding of the exposure parameters displayed on the CT images. Based on this, radiologists will be in a position to compare exposure parameters in their practice to national standards and perform necessary adjustments. Also, it should become possible to more adequately estimate patient exposure related to specific CT examinations.
Subject(s)
Patient Selection , Practice Guidelines as Topic , Quality Assurance, Health Care/organization & administration , Radiation Monitoring/standards , Tomography, X-Ray Computed/adverse effects , Tomography, X-Ray Computed/standards , Europe , France , Guideline Adherence/standards , Humans , Practice Patterns, Physicians'/standards , Radiation Dosage , Tomography, X-Ray Computed/statistics & numerical dataABSTRACT
Helical CT is the imaging modality that delivers the highest exposure to patients. For each acquisition, the average radiation dose is between 20 and 30 mGy. This dose can potentially be reduced by decreasing the intensity or voltage and by increasing the pitch. Helical data can be reformatted to obtain images with smaller increment or multiplanar reconstructions, hence reducing the need for additional acquisitions. Hardware and software devices designed for dose reduction must be systematically used. Operators of CT units should be aware of the radiation dose delivered with helical CT and must carefully assess the need of each additional acquisition. Obsolete protocols such as angulation of the gantry for lumbar CT, which increases patient exposure, should no longer be used. Rational use of helical CT decreases radiation exposure and is faster, whereas improper use increases radiation exposure without added benefit.
Subject(s)
Tomography, X-Ray Computed/instrumentation , Tomography, X-Ray Computed/methods , Filtration/instrumentation , Humans , Radiation Dosage , Technology, Radiologic , Time FactorsABSTRACT
MATERIAL AND METHODS: From July 1993 to April 1994, forty dentascans were performed at Bicetre Hospital, on an Elscint Elite Plus scanner for: chronic sinusitis (18 cases); cystic pathologies (8 cases); pre-operative assessment for dental implantation (14 cases). RESULTS: Dentascan images permitted a precise analysis of dentomaxillary anomalies. In all cases they demonstrated the anatomical relationships of the lesions, permitting a determination of potential complications. In chronic sinusitis dental pathology was demonstrated including peri-apical granulomas or cysts breaks or elevations of the floor of the maxillary sinus, malplaced dental filling material in the maxillary antrum and fistula tracks. Among the 14 pre-operative assessments, four cases of infectious lesions were demonstrated, thereby counter-indicating dental implantation. CONCLUSION: The dentascan appears to be very useful for dentomaxillary pathology by facilitating diagnosis and the formulation of treatment and operative strategies.
Subject(s)
Cysts/diagnostic imaging , Maxillary Diseases/diagnostic imaging , Maxillary Sinusitis/diagnostic imaging , Tomography Scanners, X-Ray Computed , Tooth Diseases/diagnostic imaging , Chronic Disease , Cysts/complications , Humans , Image Processing, Computer-Assisted , Maxillary Diseases/etiology , Maxillary Sinusitis/etiology , Radiography , Recurrence , Retrospective Studies , Tooth Diseases/complicationsABSTRACT
Owing to computer programs, computed tomography allows obtaining sections of the facial structures in all spatial planes and to "pile up" all sections to reconstruct the structural unit studied. In addition, these images can be reconstructed by selecting a density threshold, for example that of dentin or of enamel, isolating those from their bony environment, and thus the patient's dental arch can be visualized as if one was manipulating a pair of dental models. The first results obtained with this technique are presented, and they seem to be highly promising.