Protection of mice against mixed fission neutron-gamma (n: gamma = 1:1) irradiation by WR-2721, 16,16-dimethyl PGE2, and the combination of both agents.

The survival of mice after whole-body exposure to a modified fission neutron-gamma field (n: gamma = 1:1) was used to examine radiation protection by WR-2721, 16,16-dimethyl PGE2(DiPGE2), and the combination of both agents. Administration of WR-2721 (453 mg/kg) increased the LD50/30 from 5.24 to 7.17 Gy (DMF = 1.37), whereas pretreatment with DiPGE2 (1.6 mg/kg) increased the LD50/30 to 5.77 Gy (dose modification factor (DMF) = 1.10). The combination of 453 mg/kg WR-2721 and 0.4 mg/kg DiPGE2 resulted in an LD50/30 of 7.33 Gy, yielding a DMF of 1.39. However, no significant difference in protection was obtained with the combination of the two agents compared to that seen with WR-2721 alone.

Quantitative, functional and biochemical alterations in the peritoneal cells of mice exposed to whole-body gamma-irradiation. I. Changes in cellular protein, adherence properties and enzymatic activities associated with platelet-activating factor formation and inactivation, and arachidonate metabolism.

Changes in total number, differentials, cell protein, adherence properties, acetyltransferase and acetylhydrolase activities, prostaglandin E2 and leukotriene C4 production, as well as Ca2+ ionophore A23187 stimulation were examined in resident peritoneal cells isolated from mice 2 h to 10 days postexposure to a single dose (7, 10 or 12 Gy) of gamma-radiation. Radiation dose-related reductions in macrophage and lymphocyte numbers and increases in cellular protein and capacity to adhere to plastic surfaces were evident. In vivo irradiation also elevated the activities of acetyltransferase and acetylhydrolase (catalysing platelet-activating factor biosynthesis and inactivation, respectively) in adherent and nonadherent peritoneal cells, particularly 3-4 days postexposure. Blood plasma from irradiated animals did not reflect the increased cellular acetylhydrolase activity. Prostaglandin E2 and leukotriene C4 synthesis were elevated postexposure, suggesting increased substrate (arachidonate) availability and increased cyclooxygenase and lipoxygenase activities. Ionophore stimulation of enzyme activities and eicosanoid release also differed in irradiated peritoneal cells. While the properties of adherence, platelet-activating factor synthesis/inactivation-associated enzyme activities, and eicosanoid production are generally characterized as those of macrophages, lymphocytes or their products may influence or contribute to the observed radiation-induced changes.

Protection of mice against fission neutron irradiation by WR-2721 or WR-151327.

Two phosphorothioate compounds, WR-2721 and WR-151327, were examined for their radioprotective efficacies against the effects of fission neutron irradiation in male and female mice. Within sex groups no significant difference in lethality at 30 or 100 days postirradiation was found between WR-2721 or WR-151327 pretreatment. The dose modification factors (DMFs) for male mice treated with either compound were 1.29 (LD50/30) and 1.24 (LD50/100), and those for drug-treated female mice were 1.21 (LD50/30) and 1.19 (LD50/100). Both WR-2721 and WR-151327 were found to be equally radioprotective when compared using DMFs as the end point. WR-151327 (500 mg/kg, ip) was found to be significantly more toxic to both male and female B6D2F1 mice than equimolar amounts of WR-2721. Small but significant sex differences in radioprotection were found: the DMFs for female mice pretreated with either compound were lower than those for similarly treated male mice; the incidence of mortality 31-100 days postexposure in male mice pretreated with WR-151327 was greater than for female mice. In addition, sex differences were noted in drug toxicity. Toxic death in female mice given WR-151327 (500 mg/kg, ip) is 2.6 times more probable than in males.

Urinary excretion of cyclic nucleotides, creatinine prostaglandin E2 and thromboxane B2 from mice exposed to whole-body irradiation from an enhanced neutron field.

Urine volume and excretion of cyclic AMP, cyclic GMP, prostaglandin E2 (PGE2), thromboxane B2 (TxB2) and creatinine were evaluated as potential indicators of radiation damage in mice given 2-5 Gy to the whole body from an enhanced neutron field. In general, urinary cyclic AMP, cyclic GMP, creatinine and urine volumes were positively correlated across time postexposure, for each radiation dose. TxB2 levels positively correlated with urine volume and cyclic AMP excretion only in animals given 2.0 Gy. None of these parameters suggests their use as a prognostic indicator of the extent of radiation damage. Urinary excretion of PGE2 was negatively correlated with other urinary parameters. Biphasic increases in urinary PGE2 were also observed. The initial transient elevation 2-3 days postexposure was not correlated with the dose (2-5 Gy). The second elevation of PGE2 excretion occurred at 6-10 days. The magnitude of the latter increase suggests that urinary PGE2 excretion may be a useful indicator of whole-body or kidney exposure to neutron fields.

Prostaglandin-mediated suppression of delayed-type hypersensitivity to infected erythrocytes during Babesia microti infection in mice.

The mechanism of suppression of delayed-type hypersensitivity (DTH) to intraerythrocytic Babesia microti which occurs during infection in mice was examined. The suppression was not specific for anti-parasite DTH; infected mice immunized and challenged with sheep red blood cells had a similar depression of anti-sheep red blood cell DTH. Sublethal or lethal irradiation did not significantly alter the suppression of the DTH response, and cyclophosphamide pretreatment of infected mice also had no effect on suppression. Multiple passive transfer experiments using serum or regional lymph node cells from immunized or infected and immunized (suppressed) donor animals failed to demonstrate any ability to transfer suppression of DTH. Adherent cells from the spleens or peritoneal exudates of suppressed mice, however, did significantly depress the ability of immunized mice to express a DTH response. The cells responsible for this suppression were Thy 1- and nonspecific esterase+. Treatment of suppressive cell populations with 10 micrograms/ml indomethacin for 24 hr in vitro abrogated their suppressive ability, and in vivo administration of indomethacin to suppressed mice also restored DTH to normal levels. By examining levels of prostaglandin E2 (PGE2) in supernates of cultured peritoneal exudate cells from immune or suppressed mice, it was shown that infected mice had peritoneal exudate cells which produced significantly more PGE2 than similar cells from immune mice. These data suggest that B. microti infection elicits synthesis of PGE2 by macrophage-like cells which results in suppression of DTH to parasite as well as heterologous antigens.

In vitro prostaglandin release from guinea pig parenchymal lung tissues is not stimulated by thymic peptides.

Prostaglandins (PGs) have been demonstrated to both enhance and inhibit immune responses. As several chemically distinct serum and thymic polypeptide preparations have been shown to stimulate immunologic reactivity in several cell populations, animal models, or clinical patient trials, we have investigated the capacity of these hormone-like products from the thymus and blood to modulate PGs generation/release in normal parenchymal lung tissues of the guinea pig. Several concentrations of thymosin fraction 5, serum thymic factor, tuftsin or thymopentin, as well as histamine or A23187 (as positive controls) were exogenously applied to parenchymal lung fragments in vitro, and supernatants analyzed for PG content by radioimmunoassay. No alteration in PG levels (enhancement or suppression) from basal (spontaneous) release was found. These findings suggest that during a 30-min incubation, all four polypeptide immunomodulators were ineffective in eliciting an immediate response in the arachidonic acid cascade via the cyclooxygenase pathway.

Effects of 60Co radiation on synthesis of prostaglandins F2 alpha, E, and thromboxane B2 in lung airways of guinea pigs.

At 1 hr to 14 days after total-body exposure of guinea pigs to 3.0 Gy 60Co, changes were detected in prostaglandin concentrations in bronchial airway tissues. At 3 hr postexposure, tissue levels of PGE were significantly elevated, while at 48 hr transiently elevated levels of PGF2 alpha were observed. By 72 hr, levels returned to control values. Airway synthesis of thromboxane B2 in irradiated animals did not differ from that in controls. Also assessed were the capacities of bronchial airway preparations to respond to H-1 receptor stimulation by the exogenous addition of histamine or transmembrane divalent cation transport stimulation with ionophore. Tissues from irradiated animals demonstrated alterations in the amount and type of prostaglandins generated, varying with time postirradiation.

Radiation-induced changes in production of prostaglandins F2 alpha, E, and thromboxane B2 in guinea pig parenchymal lung tissues.

At 1 hour to 4 days after unilateral exposure of guinea pigs to a single dose (0 X 5, 1 X 5, or 3 X 0 Gy) of gamma-radiation, changes were detected in prostaglandin and thromboxane concentrations in parenchymal lung tissues. At 1-3 hours after exposure, tissue levels of PGF2 alpha, PGE, and thromboxane B2 were significantly elevated in animals receiving 3 X 0 Gy, with the magnitude of alteration revealing a radiation dose effect. By 24 hours, tissue prostaglandin and thromboxane levels returned to near control values. Lung tissue synthesis of prostaglandins in response to H-1 receptor stimulation by the exogenous addition of histamine revealed similar radiation dose effects. The carboxylic acid ionophore A23187, exogenously applied to lung tissues, revealed a transient peak of increased sensitivity to ionophore stimulation for TxB2 synthesis at 24 hours and for PGF2 alpha at 72 hours post-irradiation. The data suggest that significant alterations in prostaglandin and thromboxane concentrations in parenchymal lung tissues occur following irradiation, in a dose-dependent manner, and that altered responsiveness to H-1 receptor stimulation and divalent cation transport also occur.

Prostaglandin-generating factor of anaphylaxis. II. Characterization of activity.

Anaphylaxis of lung tissue leads to the generation of prostaglandins, thromboxanes, and hydroxyeicosatetraenoic acids. A portion of the prostaglandin generation is due to a unique oligopeptide termed "prostaglandin-generating factor of anaphylaxis (PGF-A)," which is generated during anaphylaxis. The activity of PGF-A on human and guinea pig lung was characterized: peak PG formation occurs within 5 to 10 min of the addition of PGF-A, calcium but not magnesium is required for PGF-A activity, and both physiologic pH and temperature are necessary for optimal activity. Human and guinea pig airway and parenchymal (lung) responses to PGF-A were similar (predominantely PGF2 alpha) but were not identical to each other (guinea pig parenchyma produces thromboxane as well). PGF-A is, thus, a novel, potent mediator generated during anaphylaxis of lung tissue that may contribute to the spectrum of tissue responses seen in allergic reactions.

Formation of leukotrienes C and D and Pharmacologic modulation of their synthesis.

Our attempts to find a physiologically relevant means for inducing leukotriene synthesis in rat peritoneal mononuclear cells have thus far been unsuccessful in addition to the IgE-anti-IgE challenge which we previously reported, we have now tried human C3a and C5a as well as crude and semipurified fractions of the prostaglandin-generating factor of anaphylaxis. In each case, it was possible to show that these substances activated the cells even though no leukotrienes were formed. A cell-free system in which LTC + LTD formation can be studied was developed as a modification of published methods. Arachidonic acid and LTA4 served as precursors in this system in the presence of added glutathione. Calcium was required for LTC and LTD synthesis from arachidonic acid but was not required for the glutathione S-transferase terminal step in the synthesis. Using inhibitor profiles, substrate specificity for chromogenic substrates, and inactivation by selective antibodies, we tried to identify the subtype of the glutathione S-transferase in RBL cells. Although antibody to type E of the enzyme was most effective in neutralizing the enzyme activity, neither the substrate specificity nor the inhibition profiles agreed with the conclusion that the E-type enzyme was the major form in these cells. The effect of known inhibitors of glutathione S-transferase on the conversion of arachidonate to LTC and LTD was examined. Bilirubin, an inhibitor which binds to the enzyme and is not a substrate, was much more active in inhibiting LTC + LTD formation than were steroid sulfates, which were markedly less active in inhibiting this reaction. The inhibitory activities of the other compounds were similar on all substrates tested.

RNA-dependent DNA polymerase activity in ocular granulocytic sarcoma associated to acute myelomonocytic leukemia in Turkish children. Biochemical and immunological characterization of the enzyme.

The present study describes the separation and purification of a reverse transciptiase from an orbital tumor of a patient with acute myelomonocytic leukemia. Specific reaction conditions with respect to ionic requirements and template-primers are reported. The purified enzyme was able to transcribe (rA)n . (dT)12, (rC)n . (dG)12, (OMeC)n . (dg)12 and the 70 S RNA from R(Mu)LV. Serological studies that the reverase transcriptase is antigenically related to reverse transcriptase from the type C woolly monkey virus-gibbon ape leukemia virus group.

[Experiments towards the viral etiology of a preleukemic syndrome: osteomyelofibrosis (author's transl)]. / Zur Virusätiologie eines präleukämischen Syndroms im Kindesalter (Osteomyelofibrose).

The present study describes the separation and purification of a reverse transcriptase and cellular DNA polymerases from the human spleen of a patient with myelofibrotic syndrome. The specific requirements with respect to bivalent cations and templateprimers for DNA polymerase-alpha, DNA polymerase-beta and DNA polymerase-gamma, as well as for the reverse transcriptase, are reported. Sedimentation velocity measurements of the purified enzymes gave values of 150 000, 40 000, 100 000 and 70 000 daltons for DNA polymerase-alpha, DNA polymerase-beta, and DNA polymerase-gamma and the reverse transcriptase respectively. The purified reverse transcriptase was specifically inhibited by antisera to the reverse transcriptases of the two primate viruses, SiSV and GaLV. Antisera raised against the myelofibrotic spleen reverse transcriptase inhibited the homologous enzyme and also the reverse transcriptase from SiSV and GaLV. DNA polymerases alpha, beta and gamma from the same spleen were not inhibited by the antisera. These results constitute the first indication of a possible retroviral etiology for myelofibrotic syndrome. Since SiSV and GaLV are exogenous to all primates the results indicate that this polymerase was acquired and the results are most simply interpreted as indicating that virus related to the SiSV-GaLV group is present in man.

[Molecular biological aspects of oncogenesis caused by RNA tumor viruses (author's transl)]. / Molekularbiologische Aspekte der Onkogenese durch RNA-Tumorviren.

This article concerns the molecular mechanisms by which RNA tumor viruses, commonly called as oncornaviruses, transfer their genetic information from the genomic RNA (70 s RNA) of the virions to the cellular DNA, leading to neoplastic transformations. The article describes biochemical and serological properties of reverse transcriptase, its role in the life cycle of RNA tumor viruses and broader implications to molecular biology. In this connection, the authors report their own findings on the role of reverse transcriptase in a preleukemic disease, myelofibrosis. This enzyme, discovered in their laboratory, is antigenically closely related to reverse transcriptase of certain primate RNA tumor viruses, and of human leukemic cells. The article also describes the role of reverse transcriptase inhibitors in viral oncogenesis. Of particular interest, is the partially thiolated polycytidylic acid (MPC) which has been developed by the authors, and is known to have a very high binding affinity to the viral reverse transcriptase. The implication of these basic data on the clinical effectivity of MPC in human leukemia, documented in a few cases, has been discussed.

Purification, biochemical characterization and serological analysis of cellular deoxyribonucleic acid polymerases and a reverse transcriptase from spleen of a patient with myelofibrotic syndrome.

The present study describes the separation and purification of a reverse transcriptase and cellular DNA polymerases from the human spleen of a patient with myelofibrotic syndrome. The specific requirements with respect to bivalent cations and template-primers for DNA polymerase-alpha, DNA polymerase-beta and DNA polymerase-gamma, as well as for the reverse transcriptase, are reported. Sedimentation-velocity measurements of the purified enzymes gave values of 150000, 40000, 100000 and 70000 daltons for DNA polymerase-alpha DNA polymerase-beta, DNA polymerase-gamma and the reverse transcriptase respectively. Serological studies have shown that the reverse transcriptase from human spleen is not antigenically related to cellular DNA polymerase-alpha, -beta or -gamma, but is antigenically related to reverse transcriptase from simian sarcoma virus and gibbon-ape leukaemia virus.