sodium-pertechnetate-tc-99m and indium-trichloride

Gastroretentive dosage forms have potential for use as controlled-release drug delivery systems. The use of floating dosage forms (FDFs) is one method to achieve prolonged gastric residence times (GRTs), providing opportunity for both local and systemic drug action. Multiple-unit systems avoid the 'all-or-nothing' gastric emptying nature of single-unit systems. A freeze-dried calcium alginate multiple-unit FDF has been developed which demonstrated favourable in vitro floating characteristics. The aim of this study was to investigate the in vivo behaviour of this system compared to a multiple-unit non-floating dosage form manufactured from identical material. The study was performed in seven healthy volunteers, who swallowed the radiolabelled formulations after a standard breakfast. Transit was monitored by gamma-scintigraphy and subjects were maintained in the fed state. Prolonged GRTs of over 5.5 h were achieved in all subjects for the floating formulations, which remained high up in the stomach for the whole of the test period. In contrast, the non-floating beads displayed short GRTs, with a mean onset emptying time of 1 h. The results of this study suggest that, in the fed state, this FDF has potential for sustained drug delivery for either local or systemic purposes.

Topics: Adult; Alginates; Delayed-Action Preparations; Gastric Mucosa; Humans; Indium; Male; Middle Aged; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Stomach

The aim of the present study was to explore lung microvascular leakage of protein and water in a feline model of septic shock, using a double isotope technique with external gamma camera detection and gravimetric lung water measurements. The experiments were performed on artificially ventilated cats. One group of cats (n = 8) was given an infusion of live Escherichia coli bacteria, and another group (n = 5) served as a control group receiving saline. Plasma transferrin was radiolabeled in vivo with indium-113m-chloride, and erythrocytes were labeled with technetium-99m. The distribution of these isotopes in the lungs was continuously measured with a gamma camera. A normalized slope index (NSI) was calculated, indicative of the transferrin accumulation corrected for changes in local blood volume that reflect protein leakage. In the septic group there was a protein leakage after bacterial infusion, with a NSI of 39 x 10(-4) +/- 5 x 10(-4) min-1 (mean +/- SEM), and the PaO2 diminished from 21 +/- 1 to 9.5 +/- 1 kPa. In control cats a slight protein leakage with a NSI of 9 +/- 10(-4) +/- 2 x 10(-4) min-1 was detected, probably caused by the operative procedure, but PaO2 did not change. Wet-to-dry-weight ratios of postmortem lungs were not significantly different between the groups. It was concluded that an intravenous infusion of live E. coli bacteria induces a lung capillary protein leakage without increased lung water and a concomitantly disturbed gas exchange.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Cats; Disease Models, Animal; Escherichia coli Infections; Extravascular Lung Water; Gamma Cameras; Indium; Indium Radioisotopes; Lung; Microcirculation; Organ Size; Proteins; Radioisotope Dilution Technique; Radionuclide Imaging; Shock, Septic; Sodium Pertechnetate Tc 99m; Transferrin

A commercially available system of caesium iodide crystal mini-detectors (Oakfield Instruments, Oxon, UK) was modified so that it was suitable for dual isotopic measurement of the plasma protein accumulation index (PPA)- a measure of pulmonary endothelial permeability. Using this modified system the mean PPA x 10(-3) min-1 +/- (S.E.M.) recorded in 11 normal subjects (22 lungs) was 0.18 (0.08) and in 6 patients (9 lungs) with the adult respiratory distress syndrome was 2.88 (0.63) (P less than 0.02). These values for PPA concur with those found by other groups using larger sodium iodide detectors. We conclude that with simple modification caesium iodide mini-detectors may be used successfully for the measurement of PPA in the intensive care setting.

Topics: Capillary Permeability; Cesium; Humans; Indium; Iodides; Lung; Radionuclide Imaging; Respiratory Distress Syndrome; Scintillation Counting; Sodium Pertechnetate Tc 99m

We have extended the dual isotope probe technique of Basran et al. for the measurement of pulmonary microvascular permeability (PMVP) to include gamma camera data acquisition and functional imaging of the plasma protein accumulation index (PPA) throughout the lung fields. The study group consisted of 11 patients with possible increased PMVP following the drainage of a pleural effusion or the evacuation of air from a pneumothorax, and 11 control patients. The PPA was calculated (1) for probe data, (2) on a pixel by pixel basis for the camera data, the results being stored in a functional image and (3) for four pixel x four pixel regions of interest positioned over the lung fields using the functional image and raw data as a guide. Functional images of the control group showed uniformly low PPAs throughout the lung fields. Nine of the eleven patients in the effusion/pneumothorax group showed discrete areas of increased PPA on the functional images. In the effusion/pneumothorax group, the re-expanded lung four pixel x four pixel ROI PPA values were significantly higher than the nonexpanded lung ROI values (p less than 0.001). The re-expanded lung ROI values were also significantly higher than the mean of the left and right lung ROIs in the control group (p less than 0.01). Five of the eleven patients in the effusion/pneumothorax group had probe PPAs that differed significantly from zero. We believe that probe positioning problems in the absence of sufficient clinical guidelines were largely responsible for there being no overall significant difference in the probe PPAs between the two study groups.

Topics: Adult; Aged; Capillary Permeability; Erythrocytes; Female; Humans; Indium; Isotope Labeling; Lung; Male; Middle Aged; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Transferrin

Increased microvascular permeability resulting in increased plasma protein extravasation is the hallmark of acute inflammatory oedema and hence radiolabelled proteins can be used to monitor this process. The adult respiratory distress syndrome (ARDS) is characterized by acute inflammatory oedema and thus provides an ideal model for studying this type of oedema in the human lung. A noninvasive technique applicable to the intensive care unit has been developed for monitoring the pulmonary accumulation of the plasma protein transferrin. Transferrin was radiolabelled in vivo with indium-113m and its accumulation was monitored using a portable probe radiation detector. After correcting for changes in intrathoracic blood distribution, by simultaneously monitoring the accumulation of technetium-99m-labelled red blood cells, an index of plasma protein accumulation was calculated. In all patients with established ARDS (n = 10) the index values were greater than 1.0 X 10(-3) min-1 and these were clearly separate from the values of less than 0.5 X 10(-3) min-1 in all healthy volunteers (n = 5; P less than 0.001). The technique can clearly detect raised plasma protein accumulation indices in the lungs of patients with established inflammatory oedema of ARDS and hence may provide a pharmacological tool for the rapid evaluation in these conditions of the effects of drugs (like corticosteroids) which are known to modulate inflammatory oedema.

Topics: Capillary Permeability; Humans; Indium; Lung; Methods; Microcirculation; Radioisotopes; Radionuclide Imaging; Respiratory Distress Syndrome; Sodium Pertechnetate Tc 99m; Transferrin

A comprehensive radionuclide method was used: evaluation of the time course of the absorption of a colloid radiopharmaceutical, a polyposition static examination of the liver, positive scintigraphy using tumorotropic agents and indirect radionuclide angiography of the liver. It has been established that blood flow quantitative indices changed by 1.5-2 times and the prevalence of the arterial component of the hepatic blood flow in all the segments can indicate cirrhotic lesions. A sharp decrease or a complete absence of the blood supply of "cold foci" are mostly observed in abscesses or parasitic involvement of the liver. The prevalence of the arterial component of the blood supply and the lessening of the blood supply value by 40-50% in foci of the lowered accumulation of a colloid radiopharmaceutical only with the preserved blood flow in the adjacent tissues are characteristic of primary tumor or metastatic involvement of the liver.

Topics: Colloids; Gallium Radioisotopes; Humans; Indium; Liver; Liver Circulation; Liver Neoplasms; Radioisotopes; Selenomethionine; Sodium Pertechnetate Tc 99m; Technetium; Tomography, Emission-Computed