Dennis W. Wong

A rapid chemical method of labeling human plasma proteins with 99mTc-pertechnetate at pH 7.4

Abstract A successful method for labeling human plasma proteins with 99 m Tc-pertechnetate by chemical means is described. The labeling methodology involves the production of 99 m Tc-(Sn)citrate complex species with high protein binding capacity at pH 7.4 condition following initial chemical reduction of sodium 99 m Tc-pertechnetate by stannous chloride. A combined labeling efficiency range of 95–99% for 99 m Tc-labeled fibrinogen, immune gamma globulin and serum albumin is achieved. The actual amount of labeled protein content in the product is found to be 85–95% when assayed by ITLC and 74–85% by TCAA protein precipitation. In vitro experimental data indicate that 99 m Tc-fibrinogen contains an average of 85% clottable protein with an average clottability of 95%. This strongly suggests that the radioactive proteins retain much of their biological and physiological activities after the labeling process.

A simple and efficient method of labeling hematoporphyrin derivative with 111In

Hematoporphyrin derivative (HPD) has been successfully labeled with 111In by a simple and efficient chemical process. Greater than 96% of the radionuclide is firmly bound to HPD as demonstrated by ITLC and acid precipitation radioanalyses. The radiopharmaceutical is stable at room temperature in excess of two weeks without any significant amount of dissociation of the label from the radioactive parent compound.

Labeling of human immune gamma globulin with 99mc T

Abstract Human immune serum gamma globulin and rabbit anti-Stap. aureus antibody have been successfully labeled with 99m Tcat pH 7.4 with an average binding efficiency of 86 and 82%, respectively. The labeled proteins behave similarly to unlabeled gamma-globulin fraction in normal human serum as demonstrated by protein electrophoresis. The biological half-time of 99m Tc-gamma-globulin in dog has been determined to be 54 min for the fast component and 14.7 hr for a slower component. Immunological assays demonstrate no significant change in antibody activity after labeling process.

Rapid detection of acute appendicitis with Tc-99m-labeled intact polyvalent human immune globulin.

BACKGROUND Acute appendicitis remains problematic for emergency clinicians. A rapid and definitive test is needed for detecting acute appendicitis before surgical intervention. The purpose of this clinical trial was to determine the efficacy of Tc-99m-labeled intact polyvalent human immune globulin (Tc-99m IgG) in the evaluation of acute appendicitis. STUDY DESIGN Thirty-five patients with clinically suspected acute appendicitis were evaluated with Tc-99m IgG. After the intravenous injection of 25 mCi (92.5 MBq) of Tc-99m IgG, anterior flow, single photon emission computerized tomography (SPECT) and planar delayed images of the abdomen were obtained. Any abnormal focal uptake of Tc-99m IgG in the right lower quadrant was considered to be a positive scan. RESULTS Twenty-one patients with a positive Tc-99m IgG scan underwent laparotomy and were found to have acute appendicitis. Of the 14 patients who had negative scans, 7 underwent surgery. In this series, Tc-99m IgG study yielded 21 true-positive, 12 true-negative, and 2 false-negative results with a sensitivity, specificity, and accuracy of 91%, 100%, and 94%, respectively. The positive and negative predictive values were 100% and 86%, respectively. There were no false-positive results. CONCLUSIONS Tc-99m IgG scintigraphy can provide the clinicians a simple, rapid, and definitive test for the diagnosis of acute appendicitis.

Scintigraphic detection of atherosclerotic plaques in rabbits with 111In-labeled hematoporphyrin derivative

The efficacy of 111In-labeled hematoporphyrin derivative (HPD) in localizing and detecting atheromas had been investigated with 10 atherogenic New Zealand white rabbits. Atherosclerotic plaques surgically induced in the abdominal aorta showed selective uptake of 111In-HPD over normal blood vessels averaging 0.01% ID/g tissue (range 0.003-0.023% ID/g). Normal aorta and thoracic artery concentrated an average of 0.0026% ID/g which is less than the mean blood activity of 0.0034% ID/mL. Statistical analysis demonstrated significant difference in the uptake of 111In-HPD by the atherosclerotic plaque segments as compared to normal abdominal aorta (P = 0.0023) and normal thoracic artery (P = 0.0012). In hypercholesteremic rabbits, the mean plaque segment to normal blood vessels ratio was 4:1 (range 2 to 9:1) sufficiently high to permit plaque delineation in the scintigram. Although 111In-HPD showed promise as a plaque imaging agent, further investigation with large animal models such as primates is needed to confirm current findings.

In vivo assessment of 111in-labeled hematoporphyrin derivative in breast tumor-bearing animals

The biological behavior of 111In-labeled HPD has been investigated in tumor-bearing animals. Mice mammary adenocarcinomas and 7,12-dimethylbenz(a)anthracine induced breast tumors in Sprague-Dawley female rats were clearly visualized by 111In-HPD nuclear scintigraphy. Optimal scans were obtained after a 48 h delay. In normal and tumor-bearing animals, the highest uptake of 111In-HPD 72 h post-injection was found in the liver, the spleen and the kidneys. Depending on the size and the extent of necrosis, the uptake of 111In-HPD by malignant breast tumors varied from 2.5% injected dose (ID) (range 0.14-5.3% ID) in mice to 1% (range 0.22-8.1% ID) in rats. Benign breast tumor uptake of 111In-HPD was less than 1% ID. No significant amount of the radiopharmaceutical was found in pulmonary abscesses and abdominal cysts (less than 0.1% ID). Scintigrams of these infectious or inflammatory lesions were normal. Malignant tumor to blood, heart and lung ratios averaged 50:1, 10:1 and 3:1 respectively. Tumor to brain ratio ranged from 72 to 444:1.

Conversion of 111Inoxine to 111In trichloride by acid hydrolysis

The lipophilic complex 111In-oxine was converted back to 111InCl3 by acid hydrolysis with 0.1 N HCl. Greater than 99% of the starting material was converted to 111InCl3 with a purity of 99.6%. Unlabeled oxine was completely removed by chloroform extraction. Current experimental data suggest that 111In-oxine is unstable in weak acidic medium.