Visualization of moving fluid: quantitative analysis of blood flow velocity using MR imaging

A new method for the measurement of blood flow using magnetic resonance imaging has been developed. The flow velocities are calculated from the distances that the fluid has moved. The distances are directly visualized by a new pulse sequence. In a phantom study, the measured flow rates showed very good correlation with actual flow rates of up to 20 l/min (3 m/sec). In a volunteer study, pulsatile flow velocities of a large artery were measured with electrocardiographic gating. The flow pattern of a cardiac cycle at the abdominal aorta is similar to that revealed by other methods of measurement, such as Doppler ultrasound. This method allows reasonably accurate quantitative analysis of blood flow in the large arteries.

Radioimmunodetection of human choriocarcinoma xenografts by monoclonal antibody to placental alkaline phosphatase

Placental alkaline phosphatase (PLAP)-specific monoclonal antibody (MAb) 11-D-10, which did not react with other isoenzymes of alkaline phosphatase (AP), was raised by a hybridoma technique. MAb 11-D-10 was radiolabeled and administered to athymic mice bearing human choriocarcinoma containing PLAP. This antibody was found to be more specifically localized in tumor tissue as compared to normal tissues. The tissue-to-blood ratio (T/B ratio) of MAb 11-D-10 in tumor tissue increased from 1.38 at 2 days to 2.51 at 5 days after administration. On the other hand, the T/B ratios of isotype control non-immunized IgM in tumor tissue were 0.72 and 0.87 at 2 days and 5 days after administration, respectively. 131I-labeled MAb 11-D-10 was administered to athymic mice bearing choriocarcinomas of various sizes and various PLAP contents to examine the effect on the radioimage of the differences in tumor size and PLAP content. Tumors less than 0.3 cm in diameter could be imaged clearly by gamma-scintigraphy without blood pool image subtraction. The strength of the radioimage correlated fairly well with PLAP content.

Radioimmunolocalization of monoclonal antibodies to human chorionic gonadotropin in choriocarcinoma transplanted into athymic mice

Radioimmunodetection of monoclonal antibodies to human Chorionic Gonadotropin (hCG) or its beta-subunit in choriocarcinoma tissue was investigated in athymic mouse model system. Antibody to hCG exhibited a higher localization index (L.I.) in tumor tissue than those in other organs, but the tissue/blood ratio of this antibody in tumor tissue was not so high as expected (0.38 and 0.5 on Day 2 and 5 respectively). On the other hand, antibody to beta-subunit showed the same L.I. in tumor tissue as those in other organs. Gel filtration of serum of mouse given an antibody to hCG showed that the antibody was forming immune complexes in the blood stream. Autoradiography showed many grains in the capillary vessels and intercellular spaces in the tumor tissue. We concluded that a monoclonal antibody to hCG localized in choriocarcinoma tissue via a mechanism of retention of immune complexes in the tissue, and that there may be a limitation to the clinical application of localization of antibodies to secretory products such as hCG of tumor cells from their low specific localization.

[Specific in vitro effects of methotrexate entrapped into liposomes bearing antibody fragments against human chorionic gonadotropin on cell growth of cultured human choriocarcinoma cells]

Methotrexate (MTX) was entrapped into liposomes, to which rabbit antibody fragments (Fab') against human chorionic gonadotropin (hCG) had been coupled covalently, using N-[4-(p-maleimidophenyl) butyryl] phosphatidyl ethanolamine. By this system, The resulting molar ratio in the prepared liposomes was 15 MTX per Fab', and the activities of both MTX and the antibody were well preserved. The inhibitory effects of MTX entrapped in liposomes bearing anti-hCG Fab' (Lip[MTX, anti-hCG]) on the growth of choriocarcinoma cells (BeWo) in vitro were examined. The 50% inhibitory concentration of Lip[MTX, anti-hCG] was found to be 1 X 10(-3) micrograms MTX/ml, which was significantly lower than the concentrations of control groups, free MTX (2.5 X 10(-3) micrograms/ml) or MTX entrapped in liposomes bearing no antibody (Lip [MTX], 1.3 X 10(-2) micrograms/ml). The effect of the coupling of the specific antibody was more clearly demonstrated by a short-time incubation (60 min) experiment. Lip [MTX, anti-hCG] exhibited marked inhibition on cell growth, compared to MTX entrapped in liposomes bearing non-immunized Fab' (Lip[MTX, non-immunized Fab']). On the other hand, free MTX showed no effect in this experiment. We may conclude that Lip [MTX, anti-hCG] has a specific inhibitory effect on the growth of choriocarcinoma cells in vitro, which suggests the possibility of a specific immunochemotherapy for this disease, using the specific antibody to this tumor coupled to liposomes.

Monoclonal antibodies to human chorionic gonadotropin and its beta-subunit

Using the technique of somatic cell fusion, monoclonal antibodies to human chorionic gonadotropin (hCG) and its beta-subunit were produced. Spleen cells from immunized mice were fused with the myeloma line NS-1 using 50% polyethylene glycol and cultured in a selection medium. A sensitive enzyme immunoassay was performed for antibody screening using immobilized solid-phase antigen and anti-mouse IgG Fab' (rabbit)-beta-D-galactosidase complex. Three double-cloned hybridomas (named 4H10, 4G2 and 1D12) were obtained. Anti-hCG 4H10 antibody reacted with hCG, the alpha-subunit of hCG (alpha-hCG) and human luteinizing hormone (hLH); and anti-hCG 4G2 antibody reacted with hCG and the beta-subunit of hCG (beta-hCG). It was interesting that anti-beta-hCG 1D12 antibody had the capacity to bind with free beta-hCG but not with intact hCG, which suggests that the 1D12 antibody can recognize a determinant site that is unique to beta-hCG. This unique epitope in beta-hCG might be expressed in or near a part which is hidden in the intact hCG molecule which is composed of alpha- and beta-subunits.

ECG-gated NMR-CT for cardiovascular disease

We have developed an ECG-gated NMR-CT, and used it with 16 patients. The saturation recovery images are not able to separate heart muscle from the blood pool, but in inversion recovery images, heart muscle can be differentiated from the ventricles. The region of myocardial infarction is revealed as wall thinning and/or wall motion abnormality. From the two-gated inversion recovery images (the end-diastole and end-systole images) we obtained, we evaluated a wall motion abnormality in the left ventricle, and calculated the ejection fraction of the left ventricle. This information was then compared with the findings of a nuclear medicine study carried out one week interval and which included 10 of the 16 patients tested with the ECG-gated NMR-CT. The wall motions in both methods are well correlated, with the exception of the inferior wall. The values of the ejection fraction in the NMR image were moderately low, but two modalities showed a satisfactory correlation (r = 0.85).

Huge lipomatous pseudohypertrophy of the pancreas

A rare case of lipomatous pseudohypertrophy of the pancreas associated with multiple cysts in an adult is presented. Endoscopic retrograde pancreatography showed a long, willow-like main pancreatic duct. Resected body and tail of the pancreas weighed 1,200 gm.