Photoinduced antitumour effect of hypericin can be enhanced by fractionated dosing.

The in vivo antitumour activity of the natural photosensitizer hypericin was evaluated. C3H/DiSn mice were inoculated with fibrosarcoma G5:1:13 cells. When the tumour reached a volume of 40-80mm3 the mice were intraperitoneally injected with hypericin, either in a single dose (5mg/kg; 1 or 6h before laser irradiation) or two fractionated doses (2.5 mg/kg; 6 and 1 h before irradiation with laser light; 532 nm, 70mW/cm2, 168 J/cm2). All tumours in control groups treated with hypericin alone as well as those irradiated with laser light alone had similar growth rates and none of these tumours regressed spontaneously. Complete remission of tumour in photodynamic therapy (PDT)-treated groups was similar (14-17% single dose vs. 33% fractionated dose), but the fractionated schedule of hypericin dosing was found to be more efficient than the single dose, measured by survival assay (p < 0.05). Our experimental model showed that fractionated administration of hypericin can produce a better therapeutic response than single administration.

Administration of liposomal muramyl tripeptide phosphatidylethanolamine (MTP-PE) and diclofenac in the combination attenuates their anti-tumor activities.

The anti-tumor effects of i.p. administered cyclooxygenase inhibitor - diclofenac and i.v. administered liposomal muramyl tripeptide phosphatidylethanolamine (MTP-PE) were investigated using a s.c. growing murine fibrosarcoma tumor. Tumor growth was assessed by measuring tumor volumes and survival of the mice. Both of the drugs were administered either alone or in combination. Repeated application of diclofenac in two schedules (150 microg/mouse/day for 14 consecutive days or 2 x 150 microg/mouse/week for 4 weeks) or application of liposomal MTP-PE (2 x 20 microg/mouse/week for 4 weeks) starting on day 5 after tumor cell transplantation significantly suppressed the tumor growth and increased the percentage of surviving mice. However, the volume of tumors and the survival time in tumor bearing mice treated with the two agents were similar to untreated counterparts. Thus, these data suggest the anti-tumor activity of either of the two drugs is lost when they are used in combination. Hematological examinations confirmed previously observed hematopoiesis-stimulating activities of the drugs when given alone. However, mutually potentiating effects after combined administration of liposomal MTP-PE and diclofenac were observed only exceptionally. Our findings corroborate the recommendation that the interactions of drugs used for the treatment of tumors must be carefully checked, if the drugs are applied in combination.

Photodynamic therapy of murine fibrosarcoma with topical and systemic administration of hypericin.

The in vivo antitumour activity of the natural photosensitizer hypericin was evaluated. C3H/DiSn mice inoculated with fibrosarcoma G5:1:13 cells were intraperitoneally or intratumourally injected with hypericin (5 mg/kg) and 2 hours later the mice were locally irradiated with laser light (488 nm, 150 mW/cm2, 180 J/cm2) when the tumour reached volume of 40-80 mm3 (approximately 17 days after inoculation). Tumours treated with hypericin alone as well as those irradiated with laser light alone have similar growth rates and none of these tumours regressed spontaneously. The mean tumour volume in hypericin-PDT treated groups was significantly lower in comparison to that found in the control group 3-5 weeks after the therapy. A higher proportion of animals with tumour volume less than 5-fold of the initial volume has been observed in both hypericin-PDT treated groups. Complete response to PDT has been observed for 44.4% of the animals with intraperitoneally administered hypericin and for 33.3% of the animals with intratumourally administered hypericin. Complete remission occurred in treated lesions with 3 mm or less in height. Hypericin-PDT significantly increased survival. However, no statistically significant difference in survival rate of animals has been found between the intratumoural and the intraperitoneal schedule of administration of hypericin.

Reciprocal adaptive response of human peripheral lymphocytes induced by bleomycine or gamma rays.

The adaptive response and reciprocal adaptive response induced in vitro by exposure to low doses of gamma rays (0.05 Gy) or bleomycin (0.05 microg/ml) in human peripheral blood lymphocytes were assessed by the frequency of chromosome aberrations. Gamma rays (1.5 Gy) or bleomycin (1.5 microg/ml) were used as the challenge doses. In the experiments, blood samples from 5 healthy donors were investigated. It has been found that low doses of bleomycin and gamma rays induced a reciprocal adaptive response to high doses of gamma rays or bleomycin. Moreover, the results confirmed that the adaptive response did not correlate with the radiosensitivity of the peripheral blood lymphocytes.

Cytogenetic monitoring in coke oven workers.

Cytogenetic markers (chromosomal aberrations, sister chromatid exchanges (SCE), cells with high frequency of SCE (HFC), the heterogeneity index SCE (SCE-H) and genetic polymorphism of genotypes GSTM1 and NAT2 were evaluated in the peripheral lymphocytes of 64 coke oven workers and 34 control subjects from the same plant. Personal monitors were used to evaluate exposure to eight carcinogenic (polycyclic aromatic hydrocarbons) PAHs, including B[a]P, during an 8-h working shift. Smoking habits were checked by urinary cotinine measurement. The exposure among coke oven workers ranged widely from 0.6 to 547 microgram/m3 and 2 to 50 137 ng/m3, for carcinogenic PAHs and B[a]P, respectively. The respective values in controls were 0.07 to 1.51 microgram/m3 and from 2 to 63 ng/m3. The results of biomonitoring in exposed vs. control subjects were as follows: frequency of chromosomal aberrations (% AB.C.), 2. 30% AB.C. vs. 1.09% AB.C. (P<0.05); sister chromatid exchanges, 7.47 SCE/cell vs. 5.49 SCE/cell (P<0.05); HFC, 5.94% vs. 2.06% (P<0.05) and SCE-H index, 1.49 vs. 1.01 (P<0.05). All the cytogenetic markers were significantly increased in the exposed vs. control groups. The effect of smoking was observed only in SCE when evaluated as HFC. Using individual exposure data for carcinogenic PAHs, a significant correlation between exposure and %AB.C. (r=0.372, P=0.0002), SCE/cell (r=0.331, P=0.001), HFC (r=0.467, P=0.007) and SCE/H (r=0. 286, P=0.004) was found. No effects of GSTM1 and NAT2 genotypes, individually or in combination, on the cytogenetic markers was observed. It is concluded that occupational exposure of coke oven workers involved in this study resulted in an increased level of chromosomal aberrations and SCE. The frequency of AB.C. and SCE/cell was found to be related to exposure to carcinogenic PAHs.

[The dominant lethal mutation test in the study of genetic risks of continuous exposure to low-dose ionizing radiation]. / Vyuzitie testu dominantne letálnych mutácií pre stúdium genetického rizika kontinuálne pôsobiaceho ionizujúceho ziarenia s nízkym dávkovým príkonom.

BACKGROUND: Dissension in data on the effectivity of ionizing radiation at a low-dose rate do not enable to judge the extent of the genetic risk of such exposition. This estimation, however, is especially important in cases of irradiation of female germ cells in which the lesions can cumulate and persist for a long period. OBJECTIVES: The aim of this study is to judge the mutagenic effectivity of continuous irradiation on the basis of a model experiment founded on the test of dominantly lethal mutations. METHODS: Sexually mature female ICR mice were continuously irradiated by gama rays at daily dose rates 0.01 and 0.05 Gy to a total accumulated dose of 1 Gy. The frequency of genetic lesions induced by irradiation in dictyotene oocytes was evaluated by means of the test of dominantly lethal mutations within the periods of 1-2 and 21-22 weeks after the ultimation of irradiation. RESULTS: Continuous irradiation significantly increased the frequency of dominantly lethal mutations in germ cells of female mice. Induced lesions manifest themselves mostly in form of increased values of preimplantation lethality. The level of dominantly lethal mutations persists on a significantly increased level also in the period of 21-22 weeks after the ultimation of irradiation. CONCLUSION: Continuous irradiation of female mice represents a significant risk factor which induces a long-term increase in frequency of genetic lesions in germ cells. The negative selection of lesions in the preimplantation period can be subsequently the cause of decreased reproductive abilities of irradiated animals. (Tab. 1, Fig. 2, Ref. 13.).

Effects of cadmium on haemopoiesis in irradiated and non-irradiated mice: 1. Relationship to the number of myeloid progenitor cells.

The effects of single subcutaneous injection of cadmium chloride on haemopoiesis in normal (non-irradiated) or irradiated mice were investigated. Cadmium doses used ranged from 1-8 mg/kg body weight Twenty-four hours after treatment with cadmium (doses from 3 to 8 mg/kg) there were no significant changes in bone marrow cellularity and the granulocyte-macrophage progenitor cell (GM-CFC) number per femur in non-irradiated female ICR mice. Similarly, during the 30-day postinjection period bone marrow cellularity and marrow GM-CFC number in mice treated with a cadmium dose of 5 mg/kg were not significantly different from the control values. Cadmium significantly reduced the lethal effects of gamma rays. In addition, increasing the doses of cadmium administered 24 h prior to sublethal irradiation increased the number of endogenous haemopoietic stem cells (endoCFU-S) in a concentration-dependent manner. Pretreatment with cadmium also decreased the radiation damage to endoCFU-S and haemopoietic progenitor cells committed to granulocyte/macrophage development (GM-CFC). The survival of stem cells was higher and the regeneration of cellularity and GM-CFC of irradiated bone marrow was accelerated in mice pretreated with 5 mg Cd/kg body weight in comparison with saline-injected mice.

Effects of cadmium on haemopoiesis in irradiated and non-irradiated mice: 2. Relationship to the number of circulating blood cells and haemopoiesis.

The effect of administration of cadmium alone in non-irradiated mice as well as the effect of pre-irradiation administration of cadmium on the reparation processes of haemopoiesis were investigated in mice irradiated by a dose of 7.5 Gy. The pre-irradiation administration of cadmium accelerated the reparation processes in the bone marrow and spleen as well as the number of leukocytes and thrombocytes in the peripheral blood. The administration of cadmium alone caused a temporary weight decrease of the thymus and reduced number of erythrocytes, reticulocytes and haemoglobin values in the peripheral blood. The temporary rapid increase in the number of leukocytes on the 21st day after cadmium administration was investigated.

Administration of the bacterial extract Broncho-Vaxom enhances radiation recovery and myelopoietic regeneration.

In the present study, we show that the bacterial extract Broncho-Vaxom (BV, 500 micrograms/mouse; free of endotoxin) has radiation recovery activity when administered i.p. 24 h before sublethal irradiation. In the postirradiation period (5-12 days), pretreatment of mice with BV induced significantly increased bone marrow cellularity and accelerated myelopoietic regeneration (committed progenitor granulocyte-macrophage colony-forming cells; GM-CFC) in the bone marrow compared with saline-treated controls. The earlier hemopoietic recovery in BV-injected mice was not associated with an increase in the number of bone marrow GM-CFC and CFU-S (colony-forming units-spleen) within 24 h after injection. Simultaneously, a significant diminution in bone marrow cellularity occurred. In addition, the percentage of both GM-CFC and CFU-S in the S-phase of the cell cycle was significantly increased 24 h after a single treatment. In our experiments colony stimulating activity (CSA) in the serum of treated mice was not observed within 24 h after injection. Administration of BV 24 h prior to lethal irradiation, resulted in an increase in the number of surviving mice. Combined administration of BV (24 h) and indomethacin (24 h and 3 h) to mice, prior to irradiation, caused an additional radioprotective effect. These results demonstrate that BV stimulates myelopoietic regeneration and suggest a mechanism by which this treatment protects mice from otherwise lethal irradiation.

Radioprotective effects of WR-2721, Broncho-Vaxom and their combinations: survival, myelopoietic restoration and induction of colony-stimulating activity in mice.

The possibilities of combined radioprotection, using preirradiation WR-2721 administration and post- or preirradiation Broncho-Vaxom administration in lethally whole-body gamma-irradiated mice were investigated. LD50/30 dose reduction factors (DRFs) for mice treated with WR-2721 (200 mg/kg i.p. 30 min before irradiation), Broncho-Vaxom (25 mg/kg i.p. 24 h before irradiation), or both agents were 1.92, 1.17 and 2.07, respectively. These results demonstrated at least additive radioprotective effects of both agents, manifested in increased survival of irradiated mice. Radioprotection from 17 Gy was optimal when WR-2721 in combination with Broncho-Vaxom was given 30 min before irradiation and Broncho-Vaxom 24 h before or 4-8 h after irradiation. Combined modality treatments were also more effective than individual treatments alone in accelerating the bone marrow GM-CFC restoration. During the first days after irradiation enhanced colony-stimulating activity (CSA) of the lungs was observed in mice with postirradiation injection of Broncho-Vaxom alone or in mice injected with WR-2721 and Broncho-Vaxom (8 h after irradiation), as well as in mice only irradiated.