Effects of 89Sr on the production and maturation of small lymphocytes bearing surface immunoglobulin, Fc, and complement receptors in mice

Ten-week-old C57B1/6J mice were given an intraperitoneal injection of 100 microCi radiostrontium (89Sr). One and two weeks following injection, the cellular composition of marrow and spleen was examined for cellularity, types of lymphoid cells, and incidences of small lymphocytes bearing sIgM, FcR, and CR. Strontium-89 treatment yielded a significant cell depletion in marrow, whereas spleen cellularity initially increased before returning to normal level in the second week. The increase in spleen cellularity was showed by pulse DNA labeling to be due to local production and not to influx from elsewhere. The percentage of medium and large lymphocytes, precursors of small lymphocytes, increased from 4% in the control spleen to 22% in the 89Sr-treated spleen. The incidences of small lymphocytes bearing sIgM, FcR, and CR were lower than normal levels with the exception of a substantial increase of FcR+ small lymphocytes in the spleen 2 weeks following 89Sr injection. Double-labeling studies, combining rosetting for surface receptors and DNA labeling for cell age, showed that small lymphocytes bearing sIgM, FcR, and CR form part of the major population of indigenous rapidly renewed cells in 89Sr-treated spleen.

Influence of 90Sr, adult thymectomy and antilymphocyte globulin on T-cells in mouse peripheral blood

Three groups of male CBA mice were treated by (1) 90Sr injection (14.8 kBq/g body weight i.p.), (2) adult thymectomy (ATx) + antilymphocyte globulin (ALG), and (3) 90Sr + ATx + ALG, respectively, and one untreated group served as a control. The relative number of T-lymphocytes was determined in peripheral blood mononuclear cells of individual animals using a dye exclusion cytotoxicity assay with antisera against the T-cell surface membrane marker Thy 1.2 and complement. Total and differential leucocyte counts were also performed. 90Sr irradiation decreased the total number of leucocytes irrespective of type, and the combined treatment of ATx and ALG decreased mainly mononuclear cells and particularly T-cells. The most advanced T-cell depletion in peripheral blood was found in the 90Sr + ATx + ALG treated group with a 97 per cent reduction as compared with untreated controls. ATx + ALG thus proved to be useful for blood T-cell depletion in mice treated simultaneously with 90Sr, and might provide a valuable tool in investigations on the possible role of cell-mediated immune response in radiation-induced oncogenesis, with particular emphasis on selective depletion within the monomorphonuclear compartment.

[Blastomogenic effect in rats exposed to separate uptake of osteotropic radionuclides and in combination with 131I]

A comparative study was made of tumor induction in rats by 45Ca and 90Sr administered separately and in a combination with 131I. The combination of the radionuclides was shown to reduce the occurrence of tumors as compared to 45Ca and 90Sr administered separately.

Cyclic Hematopoiesis: animal models

The four existing animal models of cyclic hematopoiesis are briefly described. The unusual erythropoietin (Ep) responses of the W/Wv mouse, the Sl/Sld mouse, and cyclic hematopoietic dog are reviewed. The facts reviewed indicate that the bone marrow itself is capable of influencing regulatory events of hematopoiesis.

[Effect of iodine-131 on the induction of osteosarcoma by strontium-90]

The paper submits the results of estimation of the osteosarcomogenic effectiveness of 90Sr in a combination with 131I incorporated prior to or after the administration of 90Sr. It was demonstrated that the incidence of osteosarcomas increased in rats received 131I a weak after the administration of 90Sr.

The role of time-factor and RBE for the induction of osteosarcomas by incorporated short-lived bone-seekers

In a large series of experiments, fractionated injections of short-lived bone-seekers have been shown in many cases to cause a remarkable increase of the osteosarcoma incidence compared with a single administration of the same total skeletal dose. This effect has been observed with both alpha- and beta-emitters. In addition the latency period was shortened by protracting the dose. The total skeletal doses investigated ranged between 0.9 and 20 Gy for alpha-emitters (224Ra and 227Th) and between 28 and 112 Gy for the beta-emitter (177Lu). In all cases the protracted dose had higher or at least equal effects when compared with a single application. Reference experiments with long-lived alpha- and beta-emitting bone-seeking nuclides (226Ra and 90Sr) showed that the incidence of osteosarcomas per Gy was sometimes lower than that observed when the same skeletal dose was applied by protraction of short-lived radionuclides. The dependence of osteosarcoma incidence on dose-time distribution, duration of internal irradiation, and radiation quality is discussed. In this context the possibility that the critical initial dose rate may be related to the initiating event within the multi-stage hypothesis of carcinogenesis is considered.

Effects of strontium-90 plus external irradiation in C57BL/6J mice

421 C57BL/6J female mice were subdivided into 11 groups. Five of these groups were given 300 rad total body irradiation from a 137Cs source at an age of 65 days. One day later, these irradiated mice were treated intraperitoneally with varying amounts of 90Sr (0, 0.032, 0.10, 0.32, and 1.0 mu Ci/g of body weight). Five groups of mice that had not been irradiated were treated on the same day with the same doses of 90Sr as given the five irradiated groups, and a sixth unirradiated group was treated with 2 mu Ci/g body weight. Each mouse treated with 90Sr and still alive was monitored between 249 and 303 days later in a total body well scintillation detector; mice with counts that differed by more than approximately 50% from the mean for their group were eliminated. A total of 402 mice were accepted for the experiment; these mice were followed to the end of their life span and then autopsied. Mice treated with the highest doses of 90Sr (1.0 and 2.0 mu Ci/g) experienced significantly elevated number of deaths from infections relative to the control group; these deaths occurred relatively early after 90Sr injection, and were particularly severe in the group of mice that had received 300 rad of external irradiation in addition to 1.0 mu Ci90Sr/g. There was no evidence of synergism between 90Sr injection and 300 rad external irradiation for production of bone tumors. Tumors of the type that occur spontaneously in C57BL/6J mice appeared to be more frequent in 90Sr-treated mice and in externally irradiated mice than in controls, but the numbers of excess tumors in these groups were not statistically significant (P less than 0.09).

Extracorporeal irradiation of dog blood: the effects of a radiostrontium irradiator on blood stem cells (CFU-C)

The radiation sensitivity of dog blood stem cells was measured in vitro and in an extracorporeal circulation passing through a radiation field. It was established that the calculated D0 was as low as 0.45 Gy. Investigating the cell killing rate in our equipment (Buchler type 90Sr device for extracorporeal irradiation), we found an overkill situation; the dose delivered was in excess of that which would be required for the total eradication of all stem cells in the peripheral blood passing through the radiation field. Various other types of devices used for extracorporeal irradiation of blood are also reviewed.

Effect of tropicamide on ocular blood flow in the rabbit

Intracardiac injection of 15 microspheres labeled with 85Sr (strontium) and 141CE (cerium) were used to determine ocular blood flow in seven rabbits before and 25 min after bilateral application of tropicamide to the cornea. By using two different isotopes distinguishable under gammaspectrometry, each animal served as its own control. After administration of two drops of 1% tropicamide, no significant difference in blood flow between treated and untreated eyes was observed.

[Outline of the technic for tagging Biomphalaria glabrata snails with radiostrontium]

Caramujos Biomphalaria glabrata vetor da esquistossomose mansônica, utilizados em experiências de campo, nas quais se faz necessário sua identificação e/ou localização, devem ser marcados com radioestrôncio 85,89 ou 90. Sua marcação em laboratório deve ser procedida em aquários de vidro sem fundo de areia, temperatura de 26,5 ± 1ºC, pH ajustado ao valor encontrado no "habitat", aeração artificial, alimentação diária com pequenas porções de alface fresca e 25 ml de água desionizada por caramujo. O nível de atividade no caramujo pode ser estimado sabendo-se que para o tempo de marcação de 5 dias e atividades iniciais de 0,036 a 0,362 µCi/ml, a captação global para grupos de 10 caramujos está em torno de 84 ± 2% e que a marcação em água contendo cálcio, praticamente não se altera até concentrações de 50ppm. A sobrevida ao longo de nove semanas não foi influenciada pela presença de radioestrôncio no caramujo.

Resident macrophage proliferation in mice depleted of blood monocytes by strontium-89

The capacity of resident peritoneal macrophages and alveolar macrophages for self-renewal was studied in CD-1 mice depleted of radiosensitive blood monocyte precursors by irradiation of the bone marrow with the bone-seeking isotope 89Sr. Thermoluminescent dosimetry and studies of DNA synthesis showed that significant levels of radiation were absorbed predominantly in anatomical sites in close proximity to bone. Cell proliferation remote from bone marrow was unaffected when quantitated by DNA precursor uptake. Between 10 and 15 days after injecting mice intravenously with 89Sr at 2 microCi per gm. of body weight, monocytes were only rarely detectable in the peripheral blood as determined by morphology, stains for nonspecific esterase and peroxidase, and by latex phagocytosis. Total numbers of resident peritoneal and alveolar macrophages were not significantly decreased and tritiated thymidine incorporation in vivo persisted at normal levels rather than regressing at a predicted rate during profound monocyte depletion. The data, therefore, suggest that local proliferation by resident macrophages in monocytopenic and intact mice is an important mechanism of population renewal.

[Tagging of Biomphalaria glabrata snails by means of radionuclides for field trials]

Os autores marcam caramujos Biomphalaria glabrata com 75Se, 59Fe, 89Sr e 90Sr e através das curvas de captação, decaimento e distribuição dos radionuclídeos na concha/partes moles do caramujo, concluem que o radioestrõncio pode ser utilizado em experiências em campo sobre dispersão e dinâmica de população de caramujos.

Microspheres in cardiac lymph: control and ischemic states

The cardiac lymph from conscious animals was monitored for the presence or absence of radiolabelled 15 micrometer microspheres during: 1) control periods after left atrial injection of microspheres and b) after circumflex coronary artery (CFX) occlusions (10--20 min total or less than 40 mins 50% of control flow) followed by full reperfusions. Microspheres (15 mu) numbering 7--150 were present in the lymph within 2 hrs after the occlusions; and in three experiments, the presence of a small number in the lymph on the following day implied continual release overnight. No microspheres were present in 8--48 hr lymph samples prior to occlusions. This study suggests that some microspheres escape from the intravascular space of the myocardium and are channeled into the cardiac lymphatics; this is apparent even after short-term ischemic events.

[Use of strontium-89 in the analgesic treatment of bone metastases]

The analgesic properties of 89Sr were investigated in 17 patients with multiple painful bone metastases. 89Sr is a radioisotope, the metabolism of which in the body is comparable to that of calcium. It is a pure beta emitter and its half-life is 51 days. When injected intravenously it is captured by bone, especially at locations where the turnover is increased. Each patient received 1--2 mCi of 89Sr. Bone scans and hematological investigations were performed before, and 2 months after, treatment. No significant changes were found. Shealy's method was used to assess pain, initially twice a week and then at more prolonged intervals. One patient suffering from multiple myeloma showed a spectacular improvement and 6 others responded favourably. Improvement generally occurred within 3--7 days, but was sometimes delayed for up to 3 weeks. Relief lasted for up to several months. Five patients had an increase of pain during the 24 hours immediately after treatment. An average of 28% of the administered radioactive dose was found in the urine collections during the first 48 hours. Although the treatment was not successful in every case, the use of 89Sr as a long acting analgesic in multiple bone metastases should be considered more frequently, especially as there are no side effects.

Marrow-dependent cells depleted by 89Sr mediate genetic resistance to herpes simplex virus type 1 infection in mice

Adult mice resistant to infection with 10(6) plaque-forming units of a virulent strain of herpes simplex virus type 1 were treated with 89Sr to abrogate marrow-dependent cell functions. Treated mice were found to be much more susceptible to the herpes simplex virus type 1 infection than untreated mice. The virus persisted in the visceral tissues of 89Sr-treated mice for 3 or more days postinfection but not in those of untreated mice. The virus also spread to the spinal cords of treated but not untreated mice. A marrow-dependent cell appeared to mediate resistance to herpes simplex virus type 1 by controlling the infection early after inoculation and not allowing the infection spread to the central nervous system.