Search

Radiation exposure due to radiological terrorism and military circumstances are a continuing threat for the civilian population. In an uncontrolled radiation event, it is likely that there will be other types of injury involved, including trauma. While radiation combined injury is recognized as an area of great significance, overall there is a paucity of information regarding the mechanisms underlying the interactions between irradiation and other forms of injury, or what countermeasures might be effective in ameliorating such changes. The objective of this study was to determine if difluoromethylornithine (DFMO) could reduce the adverse effects of single or combined injury if administered beginning 24 h after exposure. Eight-week-old C57BL/J6 young-adult male mice received whole-body cesium-137 ((137)Cs) irradiation with 4 Gy. Immediately after irradiation, unilateral traumatic brain injury was induced using a controlled cortical impact system. Forty-four days postirradiation, animals were tested for hippocampus-dependent cognitive performance in the Morris water maze. After cognitive testing, animals were euthanized and their brains snap frozen for immunohistochemical assessment of neuroinflammation (activated microglia) and neurogenesis in the hippocampal dentate gyrus. Our data show that single and combined injuries induced variable degrees of hippocampus-dependent cognitive dysfunction, and when given 24 h post trauma, DFMO treatment ameliorated those effects. Cellular changes including neurogenesis and numbers of activated microglia were generally not associated with the cognitive changes. Further analyses also revealed that DFMO increased hippocampal protein levels of the antioxidants thioredoxin 1 and peroxiredoxin 3 compared to vehicle treated animals. While the mechanisms responsible for the improvement in cognition after DFMO treatment are not yet clear, these results constitute a basis for further development of DFMO as a countermeasure for ameliorating the of risks for cognitive dysfunction in individuals subjected to trauma and radiation combined injury.

The interaction of cultured colon cancer cells with alpha-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase, has been investigated, using Raman micro-spectroscopy, in order to investigate DFMO induced effects. Raman spectra of the cultured HCT116 colon cancer cells treated with DFMO at different concentrations (0, 1, 2.5, 5, and 7.5 mM) were recorded in the range 550-2300 cm(-1). It has been shown that second derivative profile of the raw Raman spectrum of the colon cancer cells (i.e., the original experimental spectrum without any computational corrections) discriminates the weak but sharp bands from the strong, broad fluorescence background, and gives information about the position of the peaks and their band widths. The relative integrated intensities of the 781 cm(-1) and 788 cm(-1) DNA/RNA marker bands to that of 1451 cm(-1) band are found to decrease by addition of DFMO. Up to 65% reduction in the magnitude of the 1003 cm(-1) band, the characteristic phenylalanine ring breathing mode, in comparison 10 that of 1451 band, is observed. The results indicate DFMO induced apoptosis. On the other hand the intensity ratio of the tyrosine Fermi doubled around 830 cm(-1) and 850 cm(-1), which is a marker of hydrogen-bonding state of phenolic OH, is changed. The addition of DFMO may alter the tyrosine environment in cells, and parts of tyrosine residues are exposed. We also observed some modifications in amide I band, pointing out the alterations of the secondary structure of cell proteins by the presence of DFMO. (C) 2011 Elsevier B.V. All rights reserved.

To carry out a comparative study of inhibition of radiation carcinogenesis using alpha-difluoromethylornithine (DFMO), tinctures of ginseng, eleutherococcus and leuzea in female rats.Locally bred female LIO-strain rats were subjected to a single whole body γ-irradiation dose of 4 Gy at 12 weeks of age. Modifying drugs were given with drinking water from the 10th day after irradiation until the end of the experiment (for 16 months).Irradiated rats developed tumors 70.0-79.6% (malignant tumors: 43.7-45.0%) with a multiplicity of 1.48-1.75 (malignant: 0.5-0.58), while in unirradiated animals the incidence of all/malignant tumors was 21.9%/7.7% with multiplicity of 0.22/0.08. In exposed rats tumors most often developed in the mammary gland - 57.3%, reproductive and endocrine organs - 27.2%, and other localizations - 29.1%. All drugs, except leuzea, significantly reduced incidence and multiplicity of tumors, overall or at some localizations in irradiated rats. Highest, and practically equal inhibition, was shown by ginseng and DFMO, while eleutherococcus was clearly inferior. Ginseng reduced overall tumor incidence and multiplicity by 1.5 and 2.4 times, malignant tumor incidence and multiplicity - by 2.5 and 2.9 times, respectively.The ginseng extract is the most promising radiation carcinogenesis inhibitor tested.

Biochemical and pharmacologic studies suggest a role for the ornithine decarboxylase-polyamine system as a modulator of behavioral changes during vestibular compensation. alpha-Difluoromethylornithine specifically blocks the rate-limiting step of polyamine biosynthesis. To assess the effects of alpha-difluoromethylornithine on the acute phase of postural compensation, guinea pigs were divided into groups subjected to either unilateral labyrinthectomy only (n = 7), alpha-difluoromethylornithine (500 mg/kg/day) for 4 days before labyrinthectomy (n = 10), equivalent volumes of saline for 4 days before labyrinthectomy (n = 8), and sham operations (n = 5). Yaw head tilt and roll head tilt, trunk curvature, and air-righting reflex were measured at baseline and at regular intervals up to 4 weeks. alpha-Difluoromethylornithine significantly delayed recovery of normal air-righting but had no effect on yaw head tilt, roll head tilt, and trunk curvature. We also evaluated effects of alpha-difluoromethylornithine in compensated guinea pigs. Fully compensated animals from phase 1 were randomly assigned to receive alpha-difluoromethylornithine (500 mg/kg/day) or saline once daily for 4 days. Only 33% of alpha-difluoromethylornithine animals maintained air-righting, compared with 100% of saline-treated animals (p = 0.003). Maximum trunk curvature was greater in the alpha-difluoromethylornithine group (p = 0.02). Thus alpha-difluoromethylornithine not only delayed the time course for postural recovery after unilateral labyrinthectomy, it also transiently disrupted the maintenance of the compensated state.

Polyamines (PAs) are small aliphatic amines that play a major role in multicellular functions. The PA levels are controlled by ornithine decarboxylase (ODC), the rate limiting enzyme of PA biosynthesis. alpha-difluoromethylornithine (DFMO) is the ODC inhibitor, which has been shown to act as an antiproliferative agent in human cancer cells by irreversibly inhibiting ODC, which is overexpressed in breast cancer cells. Roscovitine (ROSC; CYC202), a selective cyclin-dependent kinase inhibitor, induces cell cycle arrest and concomitantly apoptosis in tumor cells. In this study, we aimed to investigate the possible role of PAs in ROSC-induced apoptosis in estrogen-dependent MCF-7 breast cancer cells. Cell viability was assessed following the exposure of MCF-7 cells to DFMO and/or ROSC by MTT cell viability assay. To evaluate the drug-induced apoptotic events, DNA fragmentation by Cell Death ELISA assay and 4,6-diamidino-2-phenylindole staining, were utilized. The disruption of mitochondrial membrane potential, caspase-9 and PARP cleavage was also determined in order to investigate the role of mitochondrial-mediated apoptosis. The modulation of Bcl-2 family members was also evaluated using the immunoblotting technique. Drug-induced reactive oxygen species was determined by a fluorometer following 2',7'-dichlorofluorescein diacetate staining. We found that ROSC induced apoptosis in a dose- and caspase-dependent manner. The ODC specific inhibitor, DFMO, altered the apoptotic effects of ROSC by increasing the generation of reactive oxygen species, decreasing the PA intracellular pool and modulating pro-apoptotic and anti-apoptotic Bcl-2 family members. All these findings suggest that ODC may be a critical target for evaluating the PA metabolic pathway as a therapeutic target in ROSC-induced mitochondrial-mediated apoptotis in estrogen-dependent MCF-7 breast cancer cells.

The spleen is the largest lymphoid organ. The uptake of 14C-putrescine in spleen increased 5 to 8 days after inoculation of sarcoma-180 tumor cells. This phenomenon is in accord with the increase of spleen weight, and its uptake by teatment with DFMO increased about 2 times that of nontreatment with DFMO. A correlation between the spleen weight and 14C-putrescine uptake in spleen is obtained. By i.p. administration of lentinan; immunopotentiator, the uptake of 14C-putrescine in spleen was significantly increased. Putrescine would be useful for a splenic immunofunctional imaging agent.

The effect of alpha-difluoromethylornithine (DFMO) administered in drinking water (0.2 and 0.5%) against liver and intestinal coccidioses in experimentally infected rabbits was studied. Zootechnical and clinical parameters were used to assess the efficacy of the compound. In both coccidioses the lower dose did not show any important effect. The higher dosage (0.5%) however, reduced the lesions induced by coccidia to an important extent. The animals infected and treated with 0.5% DFMO showed similar weight gain, food intake and relative liver weight figures to the non-infected controls. Serum transaminase levels in the rabbits infected with Eimeria stiedai and treated with 0.5% DFMO were close to those of the non-infected animals. Infected rabbits treated with this dosage also showed reductions (over 80%) in faecal oocyst output.

The purpose of these studies was to examine metastatic potentials of a human colon tumor xenograft (T6) and three different human tumor cell lines (LS174T, HT29 and A549) using the intrasplenic-nude mouse model system (ISMS model system). A further objective was to study the activity of alpha-difluoromethyl-ornithine (DFMO) against primary and metastatic growth of the xenograft and the three cell lines. DFMO is an irreversible inhibitor of ornithine decarboxylase, a rate-limiting step in polyamine biosynthesis. Tumor burdens in the liver of nude mice were observed 6 weeks after the intrasplenic injection with LS174T and 12-14 weeks after intrasplenic injections with T6, HT29 and A549. Most of the mice developed primary tumor growth in the spleens. DFMO showed significant activity against liver metastases but had little or no activity against primary tumor growth in the spleens of the ISMS model and against s.c. growth of the xenograft. The studies demonstrated that the ISMS model system is an excellent system for studying metastatic behavior of human tumors and for studying the antimetastatic activity of experimental drugs.

We have determined the pharmacokinetic parameters for diffusion of alpha-[5-14C]-difluoromethylornithine (DFMO) from blood to brain, blood to cerebrospinal fluid (CSF), 9L rat brain tumor to adjacent brain, and blood to the subcutaneously-implanted 9L tumor in rats, and within the CSF of beagle dogs. DFMO diffusion across the blood-brain and blood-CSF barriers is quite restricted in both rats and dogs, but diffusion across the defective capillary system of both subcutaneous and intracerebral 9L tumors in rats is not. Under steady-state plasma conditions in rats, uptake of DFMO by the intracerebral 9L tumor and diffusion from tumor 5-6 mm into adjacent brain is not restricted; tissue/plasma ratios were approximately 1. Therapeutic efficacy will therefore not be limited by transport of DFMO into tumor or to the extracellular environment of tumor.

The pharmacokinetics of alpha-difluoromethylornithine (DFMO), an irreversible inhibitor of polyamine biosynthesis, were investigated in BALB/c (nude) mice after i.p. injection and after oral administration of radiolabeled drug. After i.p. injection the compound was rapidly cleared from the serum (t1/2 alpha = 14 min; t1/2 beta = 2.1 h) and from tissues such as muscle, liver and kidney (t1/2 alpha = 30-60 min; t1/2 beta = 2.1 h). DFMO concentrations were proportional to the administered dose (10-2000 mg/kg) in both serum and tissues. Oral administration of DFMO was carried out by dissolving the compound in drinking water at a concentration of 20 g/l. Studies on the distribution showed that DFMO did not accumulate preferentially in any particular tissue. An extremely wide variation in the dose actually achieved in different animals was observed; this ranged from 350 to 2800 mg/kg for a 14-h treatment period. A significant correlation (r = 0.83-0.92) between the dose of DFMO, calculated from the consumption of drinking water for each individual animal, and the DFMO concentrations in serum, muscle, spleen, liver and kidney was found. Similarly, it was shown that oral administration of DFMO during the daytime resulted in 10- to 15-fold lower levels than administration during the night. After discontinuation of treatment DFMO levels in serum and tissues decreased by 50% in approximately 6 h. From these results it is concluded that the optimal treatment schedule of mice with DFMO (or other drugs with similar pharmacodynamic properties) consists in a combination of oral administration via the drinking water and additional i.p. injection (during the daytime). Furthermore, the drug intake of the individual animals should be monitored to check whether the experimental requirements are actually fulfilled.

Zusammenfassung Der Einflus von alpha-Difluromethylornithin und Weinsteinsaure auf Spermatozoendichte, Sperma γGT, FSH, LH, Testosteron und Steroidausscheidung bei Patienten mit chronischer Prostatitis In der vorliegenden Studie wurde die Hemmung der Ornithindecarboxylase durch alpha-Difluoromethylornithin (Alpha-DFMO) bei Patienten mit chronisch nicht-eitriger Prostatitis untersucht. Nach Gabe von 18 g/24 Std. alpha-DFMO kam es zu einer partiellen klinischen Besserung sowie zur deutlichen Remission bei Patienten mit Hamatospermie. Die Bestimmung von gamma-Glutamyltransferase, LH, Testosteron im Sperma anderte sich deutlich in Abhangigkeit von der alpha-DFMO-Behandlung ebenso wie sich Spermamotilitat und Vitalitat als beeinflusbar erwiesen. Ein Abfall des Hamoglobins und Hamatokrits bei 2 von 10 Patienten um 16% normalisiert sich 2 Monate nach Absetzen der alpha-DFMO-Therapie. Unter der Behandlung mit Na-Tartrat zeigten sich ahnliche klinische Besserungen des Beschwerdebildes bei chronisch nicht-eitriger Prostatitis. Die Veranderungen der Spermazahl, der seminalen Gamma-GT, des LHs und des Testosterons scheint in Zusammenhang mit der bekannten Hemmung der Prostataphosphatase durch Tartrat zu stehen.

Excerpt To the editor: Alpha-difluoromethylornithine is an investigational antiprotozoal agent used to treatPneumocystis cariniipneumonia in patients with the acquired immunodeficiency syndrome (AI...