Positron annihilation spectroscopy study of radiation-induced defects in W and Fe irradiated with neutrons with different spectra.

The paper presents new knowledge on primary defect formation in tungsten (W) and iron (Fe) irradiated by fission and high-energy neutrons at near-room temperature. Using a well-established method of positron-annihilation lifetime-spectroscopy (PALS), it was found that irradiation of W in the fission reactor and by high-energy neutrons from the p(35 MeV)-Be generator leads to the formation of small radiation-induced vacancy clusters with comparable mean size. In the case of Fe, smaller mean size of primary radiation-induced vacancy clusters was measured after irradiation with fission neutrons compared to irradiation with high-energy neutrons from the p(35 MeV)-Be generator. It was found that one of the reasons of the formation of the larger size of the defects with lower density in Fe is lower flux in the case of irradiation with high-energy neutrons from the p(35 MeV)-Be source. The second reason is enhanced defect agglomeration and recombination within the energetic displacement cascade at high energy primary knock-on-atoms (PKAs). This is consistent with the concept of the athermal recombination corrected (arc-dpa) model, although the measured dpa cross-section of both fission neutrons and wide-spectrum high-energy neutrons in W is between the conventional Norgett-Robinson-Torrens (NRT-dpa) and arc-dpa predictions. This means that the physics of the primary radiation effects in materials is still not fully known and requires further study through a combination of modeling and experimental efforts. The present data serve as a basis for the development of an improved concept of the displacement process.

[Relation between lipid-bound sialic acid in blood serum and plasma andin human tumors]. / Vztah lipidicky vázané kyseliny sialové v krevním séru a plazme k lidským nádorum.

Athymic mice with transplanted osteosarcoma and carcinoma of the rectum were found to have increased blood plasma levels of lipid-bound sialic acid (LSA). To verify the applicability of the method of LSA determination, patients with cancer of the mammary gland, rectum, and colon were examined for their LSA level. The serum LSA level was significantly increased in patients with cancer of the mammary gland and rectum, compared to levels determined in the serum of healthy volunteers. The serum LSA level elevation was even more pronounced in patients with carcinoma of the colon. In patients with carcinoma of the colon who were in remission at the time of blood collection the serum LSA level was found to be reduced to control values.

[Changes in platelet aggregation and cAMP levels in isolated blood platelets in rats after 5.0 Gy and 10.0 Gy whole-body irradiation doses]. / Zmeny agregace krevních desticek a hladiny cAMP v izolovaných krevních destickách u celotelove ozárených potkanu dávkami 5.0 Gy a 10.0 Gy.

Rats were subjected to whole-body irradiation with doses of 5.0 Gy and 10.0 Gy. After intervals of 1.5 hours, 3, 6, 12 and 24 hours following irradiation the authors tested the aggregation capacity of thrombocytes after induction with adenosine--5--diphosphate and the cAMP level in isolated thrombocytes. Statistically significant differences between experimental and control groups were found particularly at some time intervals in rats irradiated with 10.0 Gy. The authors found a significant acceleration of the time of maximal aggregation at time intervals of 3.6 and 24 hours following irradiation with 10.0 Gy. Only at the time interval of 3 hours after irradiation with 10 Gy a statistically significant reduction of the maximum aggregation, as compared with the control group, occurred, and similarly the tang alpha value indicates that also the initial rate of aggregation was lower. The cAMP level in isolated thrombocytes was markedly reduced in particular after 5.0 Gy already during the early intervals after irradiation. A temporary increase of the cAMP levels was recorded 3 hours after irradiation with 10.0 Gy which may explain the reduced aggregation capacity of thrombocytes found during the same time interval. The results of both tests are not sufficient evidence of a hypercoagulation state after irradiation with the mentioned doses within 24 hours after irradiation.

[Photodynamic therapy of human tumor xenotransplants in athymic nu/nu mice]. / Fotodynamická terapie lidských nádoru xenotransplantovaných na athymické nu/nu mysi.

The effect of phototherapy on the growth of two human tumors, i.e. carcinoma of the rectum I and III, was studied. The tumors were xenotransplated into athymic nu/nu mice. Meso-tetra-(para-sulfophenyl)-porphin, TPPS4, was used as photosensitizer. Incorporation studies showed the optimal dose for phototherapy to be 10 mg/kg TPPS4 and the time interval 72 hours. Under these experimental conditions (helium-neon laser, 632, 8, 300 J/cm2) one of six tumors was cured in the group with carcinoma of the rectum I, and that both after IV and IT administration of the photosensitizer. The other five experimental animals exhibited only partial responses to phototherapy. In the group with carcinoma of the rectum III, five out of six tumors were cured by IT administration of TPPS4 under the same experimental conditions. In one mouse there was only partial response to phototherapy. After IV administration of TPPS4, however, not a single tumor was cured and the response to phototherapy was only partial in all the six experimental animals.

An experimental immunoscintigraphic study with anti-CEA monoclonal antibody (DG2).

Monoclonal antibody D11-DG2 (DG2) against carcinoembryonic antigen (CEA) was examined for suitability for radioimmunodetection of human tumors grown in nude mice. Antibodies DG2 and a control antibody of the same IgG1 subclass were labeled with 131I and injected into mice bearing one of three types of CEA-containing tumors (cell lines LS 174T, HT-29 and Rec S) and/or a CEA-negative tumor (Rec R). Gamma-camera imaging and distribution studies revealed that CEA-containing tumors selectively accumulate DG2 but Rec R does not. As the tumors differ in CEA-content, the highest accumulation of 131I-DG2 (corresponding to the best scintigraphic imaging) was found in LS 174T tumors, intermediate in Rec S and lowest in HT-29 tumors. The mean tumor-to-blood ratios on the sixth day after antibody administration were 4.6, 3.2, and 2.1, respectively, in the control experiments the value of this parameter was always lower than 1. The results showed the applicability of DG2 for immunoscintigraphic studies in patients. Furthermore, a positive correlation was found between the uptake of anti-CEA antibody and CEA-content in the tumors.

[Immunoscintigraphy in experiments and clinical practice: its possibilities, advantages and limitations]. / Imunoscintigrafie v experimentu, klinice, její moznosti, výhody a omezení.

The authors present their experience gained in preparing, isolating and labeling antibodies with radionuclides for the purpose of using them in immunoscintigraphy. The experimental part includes results obtained with different labeled antibodies and their F/ab/2 fragments in distribution studies, involving also immunoscintigraphic imaging of tumors. The clinical part presents results of immunoscintigraphy obtained with the commercial antibody kits Iodomab and Imacis in patients with tumors of the digestive tract.

Changes of lipid-bound sialic acid in the plasma of mice bearing benzpyrene-induced tumors.

The level of lipid-bound sialic acid (LSA) was followed in inbred C57Bl/6 mice bearing tumors induced by benzpyrene at a dose of 20 mg per kg of body weight. In the plasma of mice with macroscopically ascertained tumors, the level of LSA was increased significantly. The LSA level was also significantly increased in the plasma of suspect mice i.e., in a period when the tumor was not yet macroscopically ascertained, however, when a change was observed in the motion of the hind limb of mice to which benzpyrene was administered.

[The role of prostanoids in malignant diseases]. / Uloha prostanoidu pri zhoubných onemocneních.

Prostanoids are substances which are of great regulatory importance for the organism. Recently not only their active participation in the metabolism of malignant tissue is discussed, but also the possibility of their use in the comprehensive treatment of malignant diseases. At present the effect on a reduction of metastases after prostaglandin I2 administration (= prostacycline) as well as of prostaglandin E2 is tested experimentally as they inhibit the capacity of primary tumours to form metastases. The possibility is also considered of using quantitative estimation of some prostanoids for evaluation of the severity of invasion of the organism by a malignant process.

Antiferritin antibodies in immunoscintigraphic detection of human tumor xenografts.

Affinity-purified antibodies against human placental ferritin and their F(ab)2 fragments labeled with 131I were examined for suitability for radioimmunodetection of ferritin-containing tumors. The nude mouse model (BALB/c, nu/nu) with xenografts of HeLa cell tumors and human adenocarcinoma of the rectum (with proven ferritin content) was used. Gamma-camera imaging and tissue distribution studies revealed that both kinds of tumor selectively accumulate antiferritin antibodies and their fragments. In large necrotic tumors nonspecific uptake of radiolabeled normal IgG occurred, but otherwise there was no tumor localisation. This study, in accordance with the literature, confirms the utility of antiferritin antibodies for the detection of human tumors in an animal model.

Postirradiation haemorrhagic syndrome.

One of the relevant symptoms of damage due to irradiation are the manifestations of haemorrhagic diathesis. The extravascular effusion of the blood in the course of the course of the irradiation disease may sometimes also be the cause of death of the irradiated individual, it may complicate the course of the arisen disease and sometimes even make any necessary therapeutical help impossible. The postirradiation disorder of haemocoagulation and haemostasis is a process very complicated both in its origin and in its course. Many experimental studies have been devoted to the study of the mechanism of origin of this disorder, of its course and of the possibilities of its therapy and actually we already have some clinical results. For a wider information and for the utilization of the up-to-date findings in practise, we hold it reasonable to summarize, in a certain time period, the information, though of a restricted problem, in order to facilitate an orientation in the contributions research has made up to now and to enable the selection of the adequate direction of the future experimental studies. This was the reason for the compilation of this monograph in which a summary of the up-to-date experience published in the literature and the results of our many-year standing experimental work is presented in the first opening chapter. In the second chapter, the mechanisms of blood clotting in man and the most often used laboratory animals in experiments, i.e. the dog, rabbit, rat and guinea pig, are compared. By a comparison of the platelet counts, of the time of their survival and the modes of reaction to the inductors of aggregation, some differences have been demonstrated between human thrombocytes and those of laboratory animals, which may be partly conditioned by some species specific composition of the glycoproteins of the platelet membrane. Further on, the difficulties in the determination of the levels of the individual coagulation factors are referred to and their values established in man are compared with those found in the examined laboratory animals in which decreased levels of factor VII and markedly elevated levels of factors V and VIII have been demonstrated. Next, the physiological inhibitors of blood clotting in man are compared with similar substances found in the blood of laboratory animals. Some differences in the structure and in the function of these substances slowing down the blood coagulation are stressed.(ABSTRACT TRUNCATED AT 400 WORDS)