Measurement of radiation dose to the thyroid using positron emission tomography

Measurements of the functioning volume of thyroid tissue have been made in 22 patients undergoing radioiodine therapy for thyrotoxicosis, using a prototype multiwire proportional counter positron camera. Tomographic images were produced of the distribution of 124I in the thyroid. Functioning volumes were found to be in the range 21-79 cm3 with volume errors of the order of +/- 4% to +/- 14%. Radioiodine uptake varied from 28% to 98%. Using a value of 6 days for the effective half-life of radioiodine in hyperactive thyroids, radiation doses from a standard therapy administration of 75 MBq of 131I varied from 11 to 48 Gy (compared with a recommended 50-70 Gy). In five cases PET imaging showed a non-uniform distribution of radioiodine in thyroids thought to have uniform uptake from conventional pinhole scintigraphy.

Production of gallium-66, a short-lived, positron emitting radionuclide

The excitation functions for the production of 66Ga and some other radionuclides produced by the 4He-particle bombardment of a natural copper target have been measured up to 31 MeV incident energy. The radiochemical separation of 66Ga from the irradiated copper target as well as from the other radionuclides formed is described. The yield of 66Ga at 18 MeV incident energy is 708 microCi/microAh at end of bombardment and the contamination of 67Ga is 0.25%. The intended use of the 66Ga produced is to label monoclonal antibodies for PET scanning.

Uptake of low density lipoprotein, albumin, and water by deendothelialized in vitro minipig aorta

The purpose of this research was to study the effect of pressure on arterial hydration in vitro and the effect of pressure and flow (stirred reagent) on the in vitro transport of 125I-albumin and 125I-LDL into deendothelialized minipig aortas over a 24-hour period. It was found that the arterial hydration (fractional mass of water) was 0.740 +/- 0.0043 SEM for control tissue; after 24 hours this rose to 0.745 +/- 0.0038 for 0 mm Hg, 0.752 +/- 0.0046 for 100 mm Hg, and 0.755 +/- 0.0065 for 200 mm Hg. In the transport studies, the following effects were found. The reagent radioactivity concentration and composition did not change with pressure or stirring over the 24-hour period. For unpressurized tissue, the 24-hour normalized uptake [uptake (M mg cm-2) divided by reagent concentration (co mg cm-3)] of albumin was (4.86 +/- 0.43 cm) X 10(-3) from stirred and (5.46 +/- 0.36 cm) X 10(-3) from nonstirred reagent; that of LDL was (0.31 +/- 0.02 cm) X 10(-3) from stirred and (0.37 +/- 0.02 cm) X 10(-3) from nonstirred reagent. Pressurization (100 mm Hg) of the tissue increased albumin uptake by 52% from stirred and by 125% from nonstirred reagent and the LDL uptake by 52% from stirred and 241% from nonstirred reagent. Pressure increased the intimal surface concentration of albumin and LDL at the nonstirred, but not at stirred, interfaces. The electrophoretic properties of the intimal surface fluid showed only minor differences from those of the bulk reagent. These data demonstrate that pressure causes a slight, but significant, increase in arterial hydration and that radiolabeled albumin and LDL appear to be sieved by the superficial intimal layers of the deendothelialized porcine aorta under the in vitro conditions of this study.

Representation of the path of a non-disintegrating capsule in the gastrointestinal tract using external scintigraphy and computer graphics

The intestinal transit rate of a single non-disintegrating object has been measured using gamma scintigraphy. Using computer graphics, a three-dimensional visualization of the data has been developed. The display enables viewing from any angle and should be of value in assessing the effect of variables on the transit of pharmaceuticals and other materials.

Production of cobalt-55, a short-lived, positron emitting radiolabel for bleomycin

The production and radiochemical separation of 55Co from deuteron irradiation of enriched 54Fe target is described. Methods used for the recovery and reuse of the target material (54Fe) are also described. The yield of 55Co at 12 MeV incident deuteron energy is 1.7 mCi per mu Ah at end of bombardment and the contamination with 57Co is 0.016%. The 55Co produced is chelated to bleomycin and used for tumour imaging with a positron emission tomographic camera based on multi-wire proportional chamber detectors.

Massive upper gastrointestinal hemorrhage from an arteriovenous malformation of the stomach

Arteriovenous malformations of the stomach are rare; blood loss may be manifested either by chronic anemia or by massive recurrent hemorrhage. We report a patient with massive upper gastrointestinal hemorrhage from a gastric arteriovenous malformation. Emergency operation to control hemorrhage precluded the performance of angiography; diagnosis was made from the appearance of the lesion and dilatation of the veins draining the involved area. Complete operative excision of the lesion was curative.

In vivo distribution studies of radioactively labelled platinum complexes; cis-dichlorodiammine platinum(II), cis-trans-dichlorodihydroxy-bis-(isopropylamine) platinum(IV), cis-dichloro-bis-cyclopropylamine platinum(II), and cis-diammine 1,1-cyclobutanedicarboxylate platinum(II) in patients with malignant disease, using a gamma camera

The in vivo distribution in man of the four platinum derivatives cis-dichlorodiammine platinum(II) (DDP), cis-trans-dichlorodihydroxy-bis-(isopropylamine) platinum (IV) (CHIP), cis-dichloro-bis-cyclopropylamine platinum(II) (CP), and cis-diammine 1, 1-cyclobutanedicarboxylate platinum(II) (CBDCA) has been observed. The availability of these compounds labelled with the radioactive isotope of platinum, platinum-191, has made serial in vivo imaging of their distribution possible. Injection of 17-35 MBq (5-28 mg) of the labelled compound IV was followed by imaging, using a gamma camera, with particular reference to the kidneys, liver, and tumour site. Hepatic and renal clearances were observed in all nine patients, but no unequivocal evidence of tumour uptake was found. The left kidney uptake was estimated at times up to 7 days after injection. Mathematical analysis of some of the uptake curves failed to show any significant difference between the clearance times observed. However, the two patients who received CBDCA did show a higher initial renal uptake, falling within the 1st day to levels comparable with those of the other compounds, and the three patients who received DDP showed consistently liver uptake.

Histopathological lesions in the pancreas of the BB Wistar rat as a function of age and duration of diabetes

Pancreatic histopathology was studied in 121 BBWd, 43 BBWnd, and 33 Wistar rats. Insulitis was the most common inflammatory lesion in both BBW and BBWnd rats. The incidence was inversely associated with age and with duration of diabetes in BBWd rats, but there was no age-related pattern in BBWnd rats. Small end-stage islets were typical of BBWd rats but were not seen in BBWnd rats. Several BBWd rats showed hyperplastic islets months after the onset of diabetes, a pattern that is also seen in a small percentage of human JOD patients. Several non-specific exocrine inflammatory lesions occurred in both BBWd and BBWnd rats: acute and/or chronic pancreatitis, eosinophilic infiltrates, granulomatous lesions and acute and/or chronic interstitial inflammation. Only chronic interstitial inflammation was seen in outbred Wistar rats.

Simultaneous measurement of gastric emptying of the soluble and insoluble components of a formulation using a dual isotope, gamma scintigraphic technique

The gastric emptying of a soluble and an insoluble component of a capsule formulation has been monitored by gamma scintigraphy using a dual isotope technique. There was no significant difference between the emptying rates for the two components or between fasting and non-fasting conditions (P greater than 0.01).

Blood clearance of radioactively labelled cis-diammine 1,1-cyclobutane dicarboxylate platinum (II) (CBDCA) in cancer patients

The blood and urinary clearances of cis-diammine 1,1-cyclobutane dicarboxylate platinum(II) (CBDCA, JM8) were determined in four patients with malignancy. A 40 muCi iv injection of 191 Pt/193 Pt (3:1)-labelled CBDCA was followed by serial blood and urine sampling to 72 h. The blood clearance was triphasic, mean values for the fast, intermediate, and slow phases being 10.8 min, 2.5 h, and 125 h, respectively. The fraction of activity excreted in the urine within the first 6 h had a mean value of 66.7%, contrasting with 26.4% for cisplatin. There was only a small fraction of CBDCA excreted by the slow phase (1.5%) as against an average of 20% for CHIP and 27% for cisplatin. The early and rapid renal clearance of CBDCA may account for reduced nephrotoxicity.

The influence of pancreatic juice on 64Cu absorption in the rat

The absorption of 64Cu from closed duodeno-jejunal loops in anaesthetized rats was significantly less in the presence of pancreatic juice compared with that in the presence of saline (9 g sodium chloride/l). The inhibition of 64Cu absorption caused by pancreatic juice was similar to that achieved with bile. Studies using solutions of electrolytes and of pancreatic extracts showed that the inhibitory effect of pancreatic secretions was due to its protein-enzyme content and not to its bicarbonate content. Pancreatic secretion and bile influence Cu absorption and thereby affect Cu homeostasis.

Medical biophysics in Manchester

The Department of Medical Biophysics in the University of Manchester provides research training in the application of physical and engineering sciences to biomedical problems. A wide range of projects is available for students who wish to work for MSc and PhD degrees.

Blood clearance of three radioactively labelled platinum complexes: cis-dichlorodiammine platinum II, cis, trans-dichlorodihydroxy-bis-(isopropylamine) platinum IV, and cis-dichloro-bis-cyclopropylamine platinum II, in patients with malignant disease

The blood clearances of three platinum compounds, cis-dichlorodiammine platinum II (DDP), cis, trans-dichloro-dihydroxy-bis-(isopropylamine) platinum IV (CHIP), and cis-dichloro-bis-cyclopropylamine platinum II (CP), were determined in nine patients with malignant disease. The complexes were prepared using radioactive platinum (191Pt and 193Pt). A 10-mu Ci dose of each complex, containing the equivalent of 1-2 mg elemental platinum, was injected IV into groups of three patients. Serial blood and urine samples were collected over 72 h. No obvious difference was found between the three complexes for blood clearance, median t1/2a being 16.8 (range 11.2-23.5) min and median t1/2 beta 89 (range 63.7-127) h. The urinary excretion was greatest for CHIP, 60% of injected dose as against 42.6% for CP and 38.8% for DDP. Differences in renal excretion of DDP analogues could indicate potentially less nephrotoxic agents. The use of radioactive Pt will allow in vivo dynamic imaging of the distribution of platinum compounds in areas of interest.

Factors influencing the fate of 111indium-labelled lymphocytes after transfer to syngeneic rats

Thoracic duct lymphocytes were labelled in vitro with 111indium-oxine or 111indium-acetylacetone in order to follow their migration after i.v. injection into syngeneic rats. Under certain conditions both preparations produced results with quantitatively confirmed data obtained by other approaches to the physiological pattern of lymphocyte recirculation. However, three significant difficulties were identified: (1) chemical toxicity by minor contaminants of the preparation; (2) radiation damage indicated by a progressive impairment of the recovery of radioactivity from lymph nodes. A labelling concentration of 20 microCi/10(8) cells was the highest compatible with survival of most lymphocytes for 24 h in vivo as confirmed by autoradiography; (3) rapid loss of 111In in vivo found at labelling concentrations below 1 microCi/10(8) cells. By one week after the injection of lymphocytes labelled at 20 Micro/Ci/10(8) cells most of the 111In had been transferred from lymphocytes to non-recirculating radioresistant cells within the spleen and lymph nodes.

A method for following human lymphocyte traffic using indium-111 oxine labelling

A method is described whereby large numbers of human lymphocytes are separated from peripheral blood and labelled in vitro with indium-111 oxine. Following autologous reinjection, the distribution within the body is followed by means of serial blood samples, surface-probe counting and gamma camera imaging. The distribution of radioactivity following reinjection of heat-damaged labelled lymphocytes and free indium-111 oxine is different from that of 'normal' lymphocytes. The results suggest that the separation and labelling procedure does not cause significant physical damage to the lymphocytes The importance of restricting the specific lymphocyte activity to 20-40 microCi per 10(8) cells in order to minimize radiation damage to the lymphocytes is emphasized. Good resolution of lymphoid structures is obtained using gamma camera imaging and the changes recorded in organ distribution correlate well with data from animal models of lymphocyte migration. Thus, indium-111 oxine labelling of human lymphocytes provides a non-invasive method whereby the migratory properties of human lymphocytes can be followed.

Human lymphocyte traffic assessed by indium-111 oxine labelling: clinical observations

Clinical studies using indium-111 oxine labelling of human peripheral blood lymphocytes are presented. Data from animal models of lymphocyte migration are compared with results found in healthy subjects and patients with malignant neoplasms. The physiological significance of bone marrow and liver localization on gamma camera imaging is discussed and the importance of considering the surface marker characteristics of the lymphocytes under study, when interpreting results, is emphasized. The possibility that the redistribution of lymphocytes within the body is a cause of the peripheral blood lymphopenia in patients with Hodgkin's disease and other malignancies is suggested, and the usefulness of indium-111 oxine labelling in clarifying this problem is proposed.

Retrograde spread of intrarectal hydrocortisone-containing foam

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