Kunio Nakagawa

MRI Contrast Enhancement by Gd-DTPA-Monoclonal Antibody in 9L Glioma Rats

To achieve a tissue-specific enhancement in diagnosis of brain tumor, a magnetic resonance imaging (MRI) study was performed using conjugate of Gd-DTPA and monoclonal antibody (MoAb) against 9L glioma cells. Fisher 344 strain rats were used for this study. MoAb against 9L glioma cells was conjugated with Gd-DTPA according to the method of Hnatowich et al. (1983) and used for the MRI study. The gadolinium (Gd) concentration in the Gd-MoAb injected to the rats was 0.01-0.03 mmol/kg. The enhancement effect increased gradually and persisted for 24 hours after the injection. This was longer than Gd-DTPA, which showed a peak of enhancement effect within 30 minutes after injection and was washed out within 120 min. This result was compatible with scintigraphy studies using 125I labeled anti 9L monoclonal antibody, in which the accumulation of the 125I antibody increased at 24, 48 and 72 hours after the injection. By using tumor-specific contrast agents such as Gd-MoAb, it may be possible to differentiate among tumor, perifocal edema and radiation injury.

The effect of radiation therapy combined with natural killer cells against spontaneous murine fibrosarcoma.

The effect of radiation therapy combined with lymphoid cells against spontaneous murine fibrosarcoma (FSa-II) was investigated bothin vivo andin vitro. In thein vivo experiment, syngeneic C3H mice were divided into 3 groups. Animals in the first group were injected with 1 x 105 tumor cells into the right hind leg. Animals in the second and third groups were injected with 1 x 105 tumor cells mixed with 1 x 107 normal lymphoid cells (NLC) or effector lymphoid cells (ELC), respectively. ELC were obtained from spleen and lymph nodes of FSa-II-bearing mice and incubatedin vitro for 40 hr to eliminate suppressor T cell function. NLC were obtained from normal mice and incubated in the same way. Irradiation was given using137Cs unit 3 days after cell inoculation. 12 out of 14 mice (85.7%) inoculated with tumor cells mixed with NLC did not show any tumor growth at 60 Gy local irradiation. 12 out of 21 mice (57.1 %) inoculated with tumor cells alone and 6 out of 10 (60%) with tumor cells mixed with ELC rejected tumors at the same radiation dose. This synergistic effect with NLC was not observed when NLC was inoculated after irradiation, indicating that lymphoid cells should be in contact with tumor cells before irradiation. In the51Cr release assay, lymphoid cells obtained from whole body irradiated (WBI) mice showed 17.8% lysis without irradiation and 28.8% lysis at 5 Gy irradiation. Untreated NLC showed almost no cytotoxic effect at the same radiation dose. This synergistic effect disappeared when WBI lymphoid cells were treated with anti asialo GM1 and complement. These results suggested that NK cells might be important in this synergistic effect with irradiation. To obtain a sufficient level of synergistic effect by in vitro combined treatment of mixed tumor cell - NLC culture and irradiation - incubation for more than 12 hrs and 8 hrs appeared to be necessary before and after irradiation, respectively.

Boron-, Gadolinium-Porphyrin Derivatives for Neutron Capture Therapy

New porphyrin derivatives conjugated with boron(B) or gadolinium(Gd) were developed to use as compound for neutron capture therapy in order to obtain tumor selective accumulation of B or Gd. In neutron capture therapy, it is essential to know the B or Gd distribution in the tumor and in the normal brain. Using sodium borocaptate (BSH), detection of the boron concentration in the tumor and blood before the therapy require operative sampling and additional analysis such as inductively coupled plasma (ICP) analysis (1) and still the intratumoral heterogeneity of B distribution can not be analyzed precisely. Our study was aimed to develop B or Gd compounds for neutron capture therapy which could be visualized on MRI. This compound enables preoperative evaluation of the spatial distribution of B or Gd and its clearance from the tissue without operative samplings. Such porphyrin derivatives are thought to be useful in neutron capture therapy.

The combined effect of lymphokine activated killer cell and radiation therapy on rat brain tumorin vitro

Thein vitro effect of a combined treatment with lymphokine activated killer (LAK) cell and radiation therapy on rat brain tumor was examined using51Cr release assay. The tumor cell-line used in this experiment was 9L rat brain tumor derived from a Fischer 344 rat. LAK cells were obtained by culturing rat lymphocytes with recombinant human interleukin 2 for at least 3 days. The cytotoxic activity of the LAK cells was examined by51Cr release assay. Irradiation was done by exposing the microtiter plate in which the15Cr labeled 9L cells and LAK cells were cultured to a137Cs gamma cell unit. Without irradiation, there was 18% cytotoxicity in the 1:100 tumor-to-LAK cell ratio specimen after 24 hrs cocultivation. However, if 5 Gy of irradiation was given, followed by 12 hrs incubation, the cytotoxicity was enhanced significantly at the same cell ratio (30%). This enhancement effect was the most prominent when the cell ratio was 1:100 and the irradiation dose was 5 Gy. To generate the enhancement effect, an incubation time of over 8 hrs both before and after irradiation was required. The supernatant of the LAK cells showed 19.8% and 11.4% cytotoxicity with and without irradiation, respectively. This result indicates the participation of a cytotoxic factor released from LAK cells.

Tumor Specific Contrast Enhancement Study of Mn-Metalloporphyrin (ATN-10) — Comparison of Rat Brain Tumor Model, Cytotoxic and Vasogenic Edema Models

ATN-10, Mn-metalloporphyrin, has been developed as a tumor selective contrast agent for magnetic resonance (MR) imaging. To investigate the tumor specificity of ATN-10, we produced three experimental in vivo models; rat bran tumor (9L glioma) model, vasogenic (cold injury) and cytotoxic brain edema (24-hour MCA occlusion) models. The time course of contrast enhancement was compared after intravenous injection of ATN-10 or Gd-DTPA, measuring the signal intensity of the region of interest. After ATN-10 administration, the 9L glioma model showed early (5 min) and delayed (24 hr-) peak enhancement whereas the cold injury model showed only early enhancement and the 24-hour MCA occlusion model did not show significant enhancement. After Gd-DTPA administration, all three models showed similar pattern of only early enhancement. As a contrast agent for MR imaging, ATN-10 showed different behavior than Gd-DTPA in demonstrating the blood-brain barrier disruption and moreover ATN-10 showed selective enhancement in experimental brain tumors.

Use of Photoactivation by Argon Laser in Treatment of Brain Tumors (Part I)

An attempt was made to evaluate the biological effect on the central nervous system (CNS) and the in vivo and in vitro antitumor effect of argon laser photoirradiation with or without fluorescein pretreatment. Injury to the CNS was dose-dependently evaluated by exposing mouse brains to an activating argon laser of 514.5 nm wave length, and the photoactivating effect was evaluated by exposing spinal cords of cats after administration of fluorescein. Retardation or temporary arrest in growth of mouse fibrosarcoma (Fsa II) implanted subcutaneously in C3H mice, was accomplished by exposing the tumor to an activating argon laser of 514.5 nm wave length after administration of fluorescein. Photoirradiation by argon laser proved to be dose-dependently lethal to cultured glioma cells. This preliminary study suggests a new method of treatment of human gliomas. At the same time, an extensive thermal effect to the CNS was observed.

Amplification of L-myc Oncogene in Malignant Meningioma

Amplification of L-myc oncogene was noticed in a malignant meningioma originating from the right sphenoidal wing of a 54-year-old female. The patient underwent three surgical resections plus radiotherapy over a period of 11 years and then the growth rate of the tumor became much greater with a severely invasive appearance. Using Southern blot hybridization, L-myc amplification was examined on the specimen resected at the fourth operation. As a result, approximately five-fold amplification was confirmed, which has not been previously reported except for that in a small cell carcinoma of the lung. This result may suggest that L-myc amplification is responsible to some extent for the malignant transformation in this meningioma.

The Measurement of Gadolinium Concentration in Rat Brain Tumor with NMR Analyzer for Neutron Capture Therapy

Sufficient concentration of gadolinium or boron in brain tumor is key in performing effective neutron capture therapy. As we know, the effect of neutron capture reaction is determined by the concentration of gadolinium or boron in tumor, the density of the neutron flux and radiation time. And the ratios of gadolinium concentrations in the tumor to that in normal tissues and to that in blood are important keys for successful neutron capture therapy. Gadolinium-DTPA is a commercially available and clinically safe agent for contrast enhancement in magnetic resonance imaging. The pharmacodynamics of gadolinium-DTPA in rat blood and brain tumor after intravenous infusion shows fast peak and fast wash out(1). In order to perform effective gadolinium neutron capture therapy we must develop new gadolinium compounds which show significant and continuous uptake in brain tumor. We have reported continuous significant uptake of boron or gadolinium in rat brain tumor using porphyrin derivatives(2) or monoclonal antibody(3). These gadolinium porphyrin derivatives, named Gd-ATN-10, was developed for neutron capture therapy. This molecule contains the porphyrin structure and manganese and gadolinium-DTPA(Fig.1). Gadolinium is a paramagnetic metal, which increases the intensity of T1 weighted magnetic resonance imaging and decreases the T1 relaxation time.

Suspected intraaqueductal perinatal hemorrhage in congenital hydrocephalus

A 8-day-old boy with congenital hydrocephalus was given a shunt operation. Computed tomography (CT) revealed marked internal hydrocephalus and a high density area about the aqueduct of Sylvius, in the fourth ventricle and perhaps partly in the third ventricle which was completely absorbed one month later. Later conray ventriculography demonstrated aqueductal obstruction. Neuroradiologically there was neither neoplastic nor vascular lesion. The patient achieved almost normal motor and mental development at 9 months of age. The cephalopelvic discrepancy and vacuum extraction are thought to be the most likely caused of the hemorrhage. The site of hemorrhage was quite unusual as a neonatal intraventricular hemorrhage.