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Biomedical subjects

A N Ansari

Publications and source records attributed to A N Ansari.

At least 37 records · Page 2Linked to original sources
PubMed1978

Reproducibility of ventilation studies.

Differences in ventilation patterns were observed in several instances in two consecutive ventilation studies with 127 Xe and 133Xe gas involving a group of 20 patients with COPD and other pulmonary disorders. Included were differences in the distribution of a tracer gas bolus during the initial inspiration, the distribution of gas tracer after equilibration and during gas washout, artifacts external to the lung, and variations in the half-time for gas washout. The observed discrepancies are clinically significant and could lead to erroneous or ambiguous diagnoses.

Aged↗
PubMed1978

Microautoradiographic studies on the cellular localization of radiothallium.

201Tl-chloride and 204Tl-nitrate were similarly distributed in organs of mice 10 min and 60 min after intravenous injection. Autoradiographic studies were carried out with 204Tl-nitrate in rats (injected intraperitoneally) as well as in mice and dogs (injected intravenously). Thallium localized in the cells of proximal and distal convoluted tubules and collecting tubules of the kidney. In the intestines, it was distributed mostly in the cells of the smooth musculature and surface epithelium of the villi. Some silver grains were seen in the goblet cells and in the lumen as well. It localized in the sarcoplasm of the myocardium and the skeletal muscle cells. In thyroid, most of the thallium was seen in the colloidal part of the follicle. In testes, silver grains were seen in and around the cells of Sertoli and in the lumen of the seminiferous tubules. Some localized concentration in the interstitial cells of the testes was also observed.

Animals↗
PubMed1977

Metal isotopes used as radioactive indicators of ocular melanoma.

We studied radioactive metal compounds to determine their localization in malignant Greene melanoma in the eye of the Syrian golden hamsters. Scintigraphy of an ocular melanoma was achieved with several radioactive metals: radioactive indium(111In)-bleomycin, radioactive gallium (67Ga)-citrate, and radioactive lead (203Pb)-tris. The 111In-bleomycin had the highest tumor uptake (5.45% dose/g), but not the highest tumor-to-background ratios. The 67Ga-citrate had a maximum tumor uptake of 4.87% dose/g at 48 hours. The 111In-chloride had a melanoma uptake of 2.26% dose/g, while with 203Pbtris the uptake was 1.61% dose/g. These uptake ratios compare favorably with that of radioactive phosphorus (32P)-2.21% dose/g. Noninvasive localization of malignant melanoma in the eye was accomplished with metal isotopes. Detailed analysis of in vitro uptake date by tumor and background tissues revealed the optimum time for scanning and precluded unnecessary trials.

Animals↗
PubMed1977

Thallium-201 for medical use. Part 3: Human distribution and physical imaging properties.

Studies were undertaken to determine the biologic distribution of thallium-201 in man. The disappearance from the blood is extremely rapid and intracellular deposition is nearly immediate. The biologic half-time of thallium was measured by both the Brookhaven whole-body counter and the Donner whole-body scanner, with excellent agreement. The effective whole-body half-time of thallium-201 is about 57 hr. Concentration of activity was seen in the heart, kidneys, large bowel, and thyroid. The whole-body radiation dose is 0.21 rads/mCi.

Animals↗
PubMed1977

A clinical comparison of Xe-127 and Xe-133 for ventilation studies.

Xenon-133 and xenon-127 were compared by performing ventilation studies with both radionuclides in 19 patients with a variety of lung diseases. Assessment of the counting rate over the chest, relative to the radioactivity in the lungs, permitted the evaluation of each isotope in terms of usable photons detected by a scintillation camera with a large field of view and appropriate collimation. A greater photon yield was obtained with Xe-127. Markedly improved resolution was shown by measurement of a line phantom, but was not apparent on subjective appraisal of scintiphotos except in the washout phase. Xenon-127 appears to be preferable to Xe-133 because of the higher counting rates, lower patient radiation dose, and longer shelf life. In addition, a prior perfusion study using a Tc-99m radiopharmaceutical does not affect the quality of a Xe-127 ventilation study. The use of Xe-127 therefore permits the selection for ventilation studies of only those patients with suspected pulmonary embolism, and eliminates unnecessary radiation exposure. A further improvement in image quality obtained with Xe-127 should be possible with certain modifications of the scintillation camera that would permit use of the 375-keV photopeak along with the 172- and 203-keV gamma energies. Charcoal traps designed for Xe-133 will require additional shielding and longer storage time when used for Xe-127. Xenon-127, however, might be used again after appropriate processing.

Adult↗
PubMed1976

Radiopharmaceuticals. 16. Halogenated dopamine analogs. Synthesis and radiolabeling of 6-iododopamine and tissue distribution studies in animals.

A simple halogenated derivative of dopamine, 6-iododopamine (1), has been synthesized using two different methods. These synthetic sequences have been applied to the radiolabeling of 1 with carbon-11, iodine-131, and iodine-123. The tissue distribution of 1 in mice, dogs, and rats was determined. The ratio of radioactivity (%/g) in the adrenal medulla-kidney in dogs increases from 3.45 at 2 h postinjection to 33.3 at 24 h postinjection. Thyroid uptakes in mice, dogs, and rats show that in vivo deiodination of 1 is not significant.

Adrenal Glands↗
PubMed1975

Distribution of various labeled thioglucoses in rodents.

Gold, silver and lead thioglucose were evaluated in rodents to determine the value of organo-metallic compounds in the study of metabolic abnormalities. Increased radioactivity concentration was noted in the hypothalamus with all compounds. Gold thioglucose concentrated in the kidneys and thymus, and 203Pb-thioglucose concentrated in the pancreas and thymus.

Adrenal Glands↗
PubMed1975

Thallium-201 for medical use. I.

Thallium-201 merits evaluation for myocardial visualization, kidney studies, and tumor diagnosis because of its physical and biologic properties. A method is described for preparation of this radiopharmaceutical for human use. A critical evaluation of 201Tl and other radiopharmaceuticals for myocardial visualization is given.

Cesium Isotopes↗
PubMed1975

Thallium-201 for medical use. II: Biologic behavior.

Thallium-201 has been evaluated for myocardial imaging by determining its distribution and assessing its imaging properties. Organ distribution with time was studied in goats, chosen for their large size and easy operability. Myocardial imaging was performed in living and sacrificed goats and also in two anesthetized dogs, without infarction. Infarcts were made by ligature at open chest surgery on the goats and the infarcts subsequently confirmed histologically. The myocardium of normal and infarced, young and old goats was cut into blocks and the isotope distribution measured and compared with that in the lungs, liver, spleen, and kidney in normal goats. The renal medulla-to-cortex concentration ratio in goats was studied and is approximately five. The heart uptake exceeds 3% for 100 min whereas contiguous organs have less than one-half of the myocardial concentration, and blood clearance is rapid. One problem may prove to be inhomogeneity of uptake of thallium in the "normal" myocardium, showing a standard deviation of 1u% in a young goat and 29% in an old goat. In view of the good myocardial uptake, however, this work strongly suggests the trial 201Tl in patients.

Animals↗