pyrophosphate and Brain-Neoplasms

Topics: Animals; Bone and Bones; Brain Neoplasms; Calcification, Physiologic; Calcinosis; Calcium Phosphates; Collagen; Diphosphates; Diphosphonates; Humans; Hydroxyapatites; Mice; Microscopy, Electron; Mitochondria; Odontogenic Tumors; Phospholipids; Pinealoma

Simultaneously to the development of new techniques such as the computerized axial tomography, the gamma-angioencephalography is progressing in the field of cerebral investigation in its original way, keeping on non invasing character. In view to analyze this evolution we shall examine first its technical possibilities, then the extractible data of the various techniques. Finally we will consider in which way we must bring most of our effort for the best utilization of the gamma-angioencephalography in the routine work, on one hand, and for progressing in the knowledge of the physiopathology of some lesions, specially vascular accidents, on the other hand. Technical modalities are multiple. Besides the standard technique (pertechnetate angiography with rapid sequential views, regional transit curves, early and late static views) it is possible to replace or to repete the injection: --changing the patient's position, --using another radiopharmaceutical labelled with technetium -or another isotope, or two tracers for two compartments; --carrying out a pharmacodynamic or CO2 test, --using radioxenon, and secondly a pure vascular tracer, to measure relative regional blood pool and relative regional blood flow. a) morphological ones (vascular tracks, regional blood pool, radioactive areas: number, form, homogeneity, outline), b) dynamic and quantitative ones (transit times, blood flow, extravascular diffusion, changes of these parameters when changing the radiopharmaceutic, or when using a test). Progresses can take place in three ways, very closely related to each other: a) In the methodology, to precise --relative merit of the different radiocompounds according to the various cerebral lesions, --methods for examination according to the clinical problems, --computing and date processing techniques. b) In the indications, to choose the best, the simplest, though the surest method for the daily clinical problems, and the best one to assemble special information escaping to the morphological radiological techniques. This choice needs frequent and close discussions between clinicians and nuclear specialists. c) In the signification of the data, to interprate correctly: --preferential uptakes in lesions or in compartments, --changes in the relative volumes of vascular bed and extravascular space in lesions, --vascular reactivity to an hemodynamic test, --accumulation or clearance of a diffusible tracer such as xenon. It is not always easy to reach a non equivocal

Topics: Blood Flow Velocity; Brain Diseases; Brain Neoplasms; Carbon Dioxide; Cerebral Hemorrhage; Cerebrovascular Disorders; Diphosphates; Encephalomalacia; Hematoma, Subdural; Humans; Radioactive Tracers; Radionuclide Imaging; Technetium; Xenon Radioisotopes

Medulloblastoma (MB) is the most common malignant brain tumor in children and occurs mainly in the cerebellum. Important intracellular signaling molecules, such those present in the Sonic Hedgehog and Wnt pathways, are involved in its development and can also be employed to determine tumor grade and prognosis. Ectonucleotidases, particularly ecto-5'NT/CD73, are important enzymes in the malignant process of different tumor types regulating extracellular ATP and adenosine levels. Here, we investigated the activity of ectonucleotidases in three malignant human cell lines: Daoy and ONS76, being representative of primary MB, and the D283 cell line, derived from a metastatic MB. All cell lines secreted ATP into the extracellular medium while hydrolyze poorly this nucleotide, which is in agreement with the low expression and activity of pyrophosphate/phosphodiesterase, NTPDases and alkaline phosphatase. The analysis of AMP hydrolysis showed that Daoy and ONS76 completely hydrolyzed AMP, with parallel adenosine production (Daoy) and inosine accumulation (ONS76). On the other hand, D283 cell line did not hydrolyze AMP. Moreover, primary MB tumor cells, Daoy and ONS76 express the ecto-5'NT/CD73 while D283 representative of a metastatic tumor, revealed poor expression of this enzyme, while the ecto-adenosine deaminase showed higher expression in D283 compared to Daoy and ONS76 cells. Nuclear beta-catenin has been suggested as a marker for MB prognosis. Further it can promotes expression of ecto-5'NT/CD73 and suppression of adenosine deaminase. It was observed that Daoy and ONS76 showed greater nuclear beta-catenin immunoreactivity than D283, which presented mainly cytoplasmic immunoreactivity. In summary, the absence of ecto-5'NT/CD73 in the D283 cell line, a metastatic MB phenotype, suggests that high expression levels of this ectonucleotidase could be correlated with a poor prognosis in patients with MB.

Topics: 5'-Nucleotidase; Adenosine; Adenosine Deaminase; Adenosine Monophosphate; Adenosine Triphosphate; Alkaline Phosphatase; beta Catenin; Biomarkers, Tumor; Brain Neoplasms; Cell Line, Tumor; Cerebellum; Child; Diphosphates; Gene Expression Regulation, Neoplastic; Humans; Medulloblastoma; Neoplasm Metastasis; Organ Specificity; Phosphoric Diester Hydrolases; Prognosis; Pyrophosphatases; Signal Transduction

Topics: Adult; Blood-Brain Barrier; Brain Neoplasms; Diphosphates; Humans; Leukemia; Sodium Pertechnetate Tc 99m; Technetium; Technetium Tc 99m Pyrophosphate

We sought to determine the clinical utility of using a bone-scanning agent in addition to a brain-scanning agent for the imaging of cerebral and cranial lesions. Images were obtained in 51 patients with Tc-99m diethylene-triamine-pentacetic-acid (DTPA) followed by Tc-99m pyrophosphate (PPi) within 2--5 days. The scans were qualitatively analyzed and the lesion-to-background count density ratios were determined from the corresponding brain and skull images. Only four of 20 cerebral infarctions were better demonstrated with PPi, whereas they were better with DTPA in 14 patients. They were equally good in two patients. The average lesion-to-background count-density ratio for infarction was 1.555 +/- 0.335 with DTPA and 1.428 +/- 0.573 with PPi (p < 0.05). Primary brain tumors were better visualized with DTPA in four out of five cases (p < 0.05). Metastases to brain showed up better with DTPA in 15 of 16 patients (p < 0.05), whereas all ten metastases to skull were seen better with PPi (p < 0.01). These results support previous reports regarding the radiopharmaceutical of choice for tumor imaging but not for infarction. This may be due to the differences in blood clearance for the various imaging agents.

Topics: Brain Neoplasms; Cerebral Infarction; Diphosphates; Humans; Pentetic Acid; Skull Neoplasms; Technetium; Tomography, Emission-Computed

An increase concentration of pertechnate in the choroid plexus was demonstrated in 21 patients pretreated with tin pyrophosphate injected intravenously 24 hours before the examination. Using this technique, the choroid plexus are seen quite clearly, giving indirectly a picture of the intracerebral ventricles. A dynamic study was carried out in 12 patients, 3 of whom had abnormalities of the cerebrospinal fluid circulation demonstrated by isotope cisternography. The results obtained were characterised by a typical diphasic curve with variations in the pathological cases.

Topics: Brain Neoplasms; Cerebral Ventricles; Cerebrospinal Fluid; Choroid Plexus; Cisterna Magna; Diphosphates; Humans; Hydrocephalus; Injections, Intravenous; Radionuclide Imaging; Technetium; Tin

Topics: Brain Neoplasms; Cell Nucleus; Dactinomycin; Diphosphates; Glioblastoma; Glioma; Humans; Hydrogen-Ion Concentration; In Vitro Techniques; Meningioma; Nucleotides; RNA Nucleotidyltransferases; RNA, Neoplasm; Tissue Extracts