[Index of tumor response by in-vivo 31P-MRS--T1 effect as a new predicting index of therapeutic effects].

We observed the metabolism of the Yoshida sarcoma by in-vivo 31P-MRS, using two varieties of repetition time (TR), i.e., TR2s and TR10s. It was measured before the injection of 5FU and 4, 24, 48 hours after the injection. In the each time, PME/ATP ratio, intracellular pH, and TR10/TR2 ratio of PME which reflects the T1 value of PME, were calculated. TR10/TR2 ratio of PME decreased 4 and 24 hours after the injection of 5FU and recovered 48 hours after the injection to the same level before the injection. However decrease of PME/ATP ratio was not observed until 48 hours after the injection of 5FU, when apparent tumor regression appeared. These results suggested that the T1 value of PME decreased prior to the PME changes and when the PME decreased, the intracellular environment of PME recovered to the same state before the therapy. It was considered that the TR10/TR2 ratio of PME offers significant information different from the PME/ATP ratio. It is possible to use the TR10/TR2 ratio as a predicting index for the therapeutic effects.

Contrast enhancement of magnetic resonance images by chromium EDTA: an experimental study.

Chromium EDTA was evaluated as an intravenous contrast agent for magnetic resonance (MR) imaging in vitro and in vivo in rabbits and rats. The effect of Cr EDTA on T1 and T2 values in vitro was first quantitated by spectroscopy at 2.5 MHz, followed by animal trials in which the effects of intravenous injection of Cr EDTA on calculated T1 MR images (obtained by the spin- warp technique at 1.7 MHz) were determined. Following administration of chromium EDTA, differences in T1 values between normal and abnormal kidneys were noted, renal hydronephrosis and renal ischemia were readily identified by the pattern of change in T1, and changes were observed in the normal rabbit brain and in tumors implanted in rats. It is concluded that the use of stable paramagnetic metal ion chelates, such as Cr EDTA, as intravenous contrast agents in MR imaging is feasible and that such agents would make possible the observation of tissue vascularity, breakdown of the blood-brain barrier, and renal function.

[Animal experimental studies of positive tumor demonstration with radio-iodine labelled albumin macroaggregates]. / Tierexperimentelle Untersuchungen zur positiven Tumordarstellung mit radiojodmarkierten Albumin-Makroaggregaten

131I-labeled macroaggregates were injected into the femoral artery of rats bearing a Yoshida sarcoma at the lower extremity and of healthy control animals. The radioactivity was measured in tissue samples taken from the tumour and in unaffected muscle tissue. The tumour tissue showed a considerably higher uptake of radioactivity than the not-neoplastic tissue of control animals. The difference was increased when more time elapsed between the injection and the measurement. After 48 hours the ratio was 25:1 in favour of tumour tissue. In contrast to the transplanted Yoshida sarcoma, hepatomas in Wistar rats induced by N-nitroso-morpholin showed a considerably smaller increase of radioactivity than the control group when injected with 131I-MAA. The fixation ratio between tumour and normal liver tissue was 1:5.9. In contrast to autochtone liver tumours rats with transplanted tumours are considered as a suitable model for testing labeled albumin particles like 131I-, 111In- or 99mTc-labelled albumin microspheres developed for angioscintigraphic purposes.

Growth of metastases from P-388 sarcoma in the rat followig whole body irradiation.

The growth of an allogeneic rapidly growing and metastasizing sarcoma (P-388) in the rat is described. Quantitative and kinetic data are provided concerning the growth of individual metastases produced in three principal regional lymph node drainage groups, and are compared with growth of the primary tumour of origin in muscle; the incidence of pulmonary metastases is also given. The effects on growth of metastases and primaries produced by sublethal whole body irradiation (WBI) before inoculations of 10-10(8) tumour cells are described.Growth of P-388 sarcoma in unirradiated recipients (ED(50) ≃ 5 × 10(3) cells) obeyed the linear growth law proposed by the Mayneord model for tumour growth, but in irradiated recipients (ED(50) < 10 cells) early growth of primaries and metastases approximated more closely to an exponential rate of growth.The ratio M/P of weight of metastases (M) to weight of primary tumour of origin (P) increased at a linear rate with age (t) of tumour, and gave the same slope namely, 0·029 for pelvic node metastases) in unirradiated rats inoculated with a large (10(6)-10(7)) number of cells as in irradiated rats. The slope was decreased to 0·014 for pelvic node metastases in unirradiated rats challenged with fewer (10(4)) cells but not in irradiated recipients. It is postulated that the effects of WBI on growth of metastases are confined to causing a suppression of immunity, and that WBI does not affect tumour spread significantly through other mechanisms.In immunologically competent rats the phenomena of sequestrated progressive growth of isolated metastases in lymph nodes and of a chronic nonprogressive enlargement of nodes in which persistent tumour growth and destruction occurred side by side are described, and effects on prognoses and clinical behaviour, are discussed.The P-388 tumour is considered of value in quantitative and kinetic experimental studies of metastases, and particularly those in which the role of immunity needs to be assessed and measured to avoid confusion with other factors or agents which might affect the spread and growth of metastases.