Male Balb-c Mice Research Articles

Spinal 5-HT7 Receptors Play an Important Role in the Antinociceptive and Antihyperalgesic Effects of Tramadol and Its Metabolite, O-Desmethyltramadol, via Activation of Descending Serotonergic Pathways

Tramadol is an analgesic drug, and its mechanism of action is believed to be mediated by the mu-opioid receptor. A further action of tramadol has been identified as blocking the reuptake of serotonin (5-HT). One of the most recently identified subtypes of 5-HT receptor is the 5-HT7 receptor. Thus, the authors aimed to examine the potential role of serotonergic descending bulbospinal pathways and spinal 5-HT7 receptors compared with that of the 5-HT2A and 5-HT3 receptors in the antinociceptive and antihyperalgesic effects of tramadol and its major active metabolite O-desmethyltramadol (M1) on phasic and postoperative pain models. Nociception was assessed by the radiant heat tail-flick and plantar incision test in male Balb-C mice (25-30 g). The serotonergic pathways were lesioned with an intrathecal injection of 5,7-dihydroxytryptamine. The selective 5-HT7, 5-HT2, and 5-HT3 antagonists; SB-269970 and SB-258719; ketanserin and ondansetron were given intrathecally. Systemically administered tramadol and M1 produced antinociceptive and antihyperalgesic effects. The antinociceptive effects of both tramadol and M1 were significantly diminished in 5-HT-lesioned mice. Intrathecal injection of SB-269970 (10 microg) and SB-258719 (20 microg) blocked both tramadol- and M1-induced antinociceptive and antihyperalgesic effects. Ketanserin (20 mumicrog) and ondansetron (20 microg) were unable to reverse the antinociceptive and antihyperalgesic effects of tramadol and M1. These findings suggest that the descending serotonergic pathways and spinal 5-HT7 receptors play a crucial role in the antinociceptive and antihyperalgesic effects of tramadol and M1.

Protective effect of resveratrol against naphthalene-induced oxidative stress in mice

Objective This investigation confirms the role of free radicals in naphthalene-induced toxicity and elucidates the mechanism of resveratrol (RVT). Methods Both male and female BALB-c mice were administered with naphthalene (100 mg/kg, i.p.) for 30 days, either along with saline or along with RVT (10 mg/kg, orally). At the end of the experiment, following treatment and sacrifice of animals by decapitation, lung, liver and kidney tissue samples were taken for histological examination or determination of malondialdehyde (MDA), glutathione (GSH), myeloperoxidase (MPO) activity and collagen contents. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN) and creatinine levels and lactate dehydrogenase (LDH) activity were measured in the serum samples, while TNF- α, IL- β, IL-6 and total antioxidant capacity (AOC) were assayed in plasma samples. Results Naphthalene administration caused a significant decrease in tissue GSH and plasma AOC, which was accompanied with significant increases in tissue MDA and collagen levels and MPO activity. Moreover, the pro-inflammatory mediators (TNF- α, IL- β, IL-6), LDH activity, AST, ALT, creatinine and BUN levels were significantly increased in the naphthalene group. On the other hand, RVT treatment reversed all these biochemical indices as well as histopathological alterations induced by naphthalene. Conclusions Oxidative mechanisms play an important role in naphthalene-induced tissue damage, and RVT, by inhibiting neutrophil infiltration, balancing oxidant–antioxidant status, and regulating the generation of inflammatory mediators, ameliorates oxidative organ injury due to naphthalene toxicity.

Locally applied Simvastatin improves fracture healing in mice

BackgroundHMG-CoA reductase inhibitors, statins, are widely prescribed to lower cholesterol. High doses of orally administered simvastatin has previously been shown to improve fracture healing in a mouse femur fracture model. In this study, simvastatin was administered either subcutaneously or directly to the fracture area, with the goal of stimulating fracture repair at acceptable doses.MethodsFemur fractures were produced in 70 mature male Balb-C mice and stabilized with marrow-nailing. Three experiments were performed. Firstly, 20 mice received subcutaneous injections of either simvastatin (20 mg) or vehicle. Secondly, 30 mice were divided into three groups of 10 mice receiving continuous subcutaneous delivery of the vehicle substance, the vehicle with 5 mg or with 10 mg of simvastatin per kg bodyweight per day. Finally, in 20 mice, a silicone tube was led from an osmotic mini-pump to the fracture area. In this way, 10 mice received an approximate local dose of simvastatin of 0.1 mg per kg per day for the duration of the experiment and 10 mice received the vehicle compound. All treatments lasted until the end of the experiment. Bilateral femurs were harvested 14 days post-operative. Biomechanical tests were performed by way of three-point bending. Data was analysed with ANOVA, Scheffé's post-hoc test and Student's unpaired t-test.ResultsWith daily simvastatin injections, no effects could be demonstrated for any of the parameters examined. Continuous systemic delivery resulted in a 160% larger force at failure. Continuous local delivery of simvastatin resulted in a 170% larger force at failure as well as a twofold larger energy uptake.ConclusionThis study found a dramatic positive effect on biomechanical parameters of fracture healing by simvastatin treatment directly applied to the fracture area.

Intestinal Ischemia-Reperfusion Injury Alters Purinergic Receptor Expression in Clinically Relevant Extraintestinal Organs

Intestinal ischemia-reperfusion (IIR) injury is known to initiate the systemic inflammatory response syndrome, which often progresses to multiple organ failure. We investigated changes in purinoceptor expression in clinically relevant extra-intestinal organs following IIR injury. Anesthetized adult male BalbC mice were randomized to sham laparotomy (control, n = 5), or 15 min of superior mesenteric artery occlusion. Experimental ischemia was followed by a period of reperfusion [1 min (n = 6) or 1 h (n = 6)]. Mice were then sacrificed and lung, kidney, and intestinal tissues were harvested. Following RNA extraction, purinoceptor mRNA expression for P2Y2, A3, P2X7, A2b, P2Y4, and P2Y6 was analyzed using real-time RT-PCR. Significant differences in purinoceptor expression were observed in the lungs and kidneys of mice exposed to IIR injury when compared to controls. Pulmonary P2Y2 receptor expression was increased in the 1 h IIR group when compared to control, while pulmonary A3 receptor expression was incrementally elevated following IIR injury. In the kidney, P2Y2 receptor expression was increased in the 1 h IIR group compared to both 1 min IIR and control, and A3 receptor expression was decreased in the 1 h IIR group compared to the 1 min IIR group. No significant changes were observed in the intestinal purinoceptor profiles. Purinoceptor expression is altered in the murine lung and kidney, but not intestine following experimental IIR injury. These findings may implicate extracellular nucleotides and purinoceptors as possible mediators of the extra-intestinal organ dysfunction associated with IIR injury.

Gemcitabine and capecitabine synergism and biomodulation with dipridamole in a mouse tumor model

12034 Background and Aim: Gemcitabine and capecitabine are antimetabolites that are effective in the pyrimidine pathway of the DNA synthesis. Capecitabine through a 3-step activation process is transformed to 5-FU in the tumor cell by thymidine phosphorilase. On the other hand, gemcitabine interacts with the enzymes thymidine kinase, tymidine phosphorilase ve ribonucloetide reductase. Our hypothesis is based on a possible synergistic blockade by concurrent administration of these two antimetabolites. Additionally, dipridamole is an inhibitor of the nucleoside transport; and that can prolong the accumulation of antimetabolites within the tumor cell. In this study, combinations of these drugs are tested on an animal model. Methods and Results: 80 male balb-c mice were inoculated dorsally with 0.1 cc Ehrlich ascites tumor, and 10 days later the animals were separated into 5 groups having a similar tumor load. The control group received no treatment, while in the gemcitabine arm the animals received 50 mg/d gemcitabine on day 1. In the capecitabine arm, the animals received 1mg/day capecitabine administered in drinking water on days 1–4. In the gemcitabine + capecitabine combination arm, the animals received both treatments. In the gemcitabine + capecitabine + dipridamole arm, in addition to both of the drugs, dipridamole was also given 2mg/day in drinking water on days 1–4. In the control group (n=16) median survival was 17 days, while it was 33 days in gemcitabine arm (n=11), 35 days in capecitabine arm (n=14), and 44 days in the gemcitabine + capecitabine combination arm (n=22) which was significantly higher (p<0.007). Dipridamole added to this combination (n=17) did not prolong survival any further. Conclusion: combination of gemcitabine with capecitabine suggests favorable results in an animal model. Testing of this combination in clinical trials seems to be justified. No significant financial relationships to disclose.

Purinergic receptor expression is altered in extra-intestinal organs following intestinal ischemia/reperfusion injury

Background: Intestinal ischemia/reperfusion (IIR) injury is known to initiate the systemic inflammatory response syndrome, often progressing to multiple organ failure, resulting in significant morbidity and mortality. Pro-inflammatory cytokines released following IIR injury have been implicated as mediators in the associated extra-intestinal manifestations of this disease process, specifically pulmonary and renal dysfunction. Extracellular nucleotides are known to be released in response to ischemic stress, and modulate a host of pro-inflammatory responses via interactions with purinergic receptors. In this study, we investigate the hypothesis that purinergic receptor expression is altered in clinically relevant extra-intestinal organs following IIR injury. Methods: Adult male BalbC mice (n=17; wt: 30.0 +/− 3.3 grams) were anesthetized and randomized to receive either sham laparotomy (control, n=5), or 15 minutes of superior mesenteric artery occlusion. Experimental ischemia was followed by a subsequent period of reperfusion[1 minute (n=6) or 1 hour (n=6)]. The mice were then sacrificed, and lung, kidney, and intestinal tissues were harvested for analysis. Following RNA extraction, purinergic receptor mRNA expression for P2×7, P2Y2, P2Y4, P2Y6, A2b and A3, was analyzed with real-time RT-PCR using previously optimized intron-spanning murine primers. Receptor gene patterns were normalized as a ratio of cyclophilin A expression. Results: Significant differences in tissue purinergic receptor expression were observed in both the lungs and kidneys of mice exposed to IIR injury when compared to controls. In the lung, P2Y2 receptor expression was increased in the 1 hour IIR group when compared to control (1.687 +/− 0.227 vs. 1.014 +/− 0.116; p<0.05). Pulmonary A3 receptor expression was incrementally elevated following intestinal ischemia/reperfusion injury (ctrl. 1.042 +/− 0.213 vs. IIR 1 hr. 2.093 +/− 0.142 and IIR 1 min. 1.239 +/− 0.306 vs. IIR 1 hr.; p<0.05). In the kidney, P2Y2 receptor expression was increased in the 1 hour IIR group compared to both 1 minute IIR and control (IIR 1 hr. 1.845 +/− 0.333 vs. IIR 1 min. 0.911 +/− 0.137 and vs. ctrl. 0.717 +/− 0.276; p<0.05). A3 receptor expression in the kidney was decreased in the 1 hour IIR group compared to the 1 minute IIR group (0.496 +/− 0.121 vs. 1.436 +/− 0.261; p<0.05). No significant changes were noted in the intestinal tissue purinergic receptor profiles. Conclusion: Purinergic receptor expression patterns are altered in the lung and kidney following intestinal ischemia/reperfusion injury. Intestinal purinergic receptor expression patterns are unchanged following experimental ischemia/reperfusion injury. These findings may implicate extracellular nucleotides and their receptors as possible mediators of extra-intestinal organ dysfunction associated with intestinal ischemia/reperfusion injury.

Optical imaging of protease activity in rheumatoid arthritis

at room temperature the product was purified on a G25 column. The Cy5.5 density for both agents was approximately 8 per dextran T70. Male BALB-c mice (10 mg/kg ketamine, 1 mg/kg acepromizin IP) were imaged in the SAMI imaging system (Advanced Research Technologies). Cy5.5-DTPAdextran or Cy5.5-DTPA-galactosyl-dextran was administered (24 nmole/kg dextran) via a tail vein injection. The animals were positioned supine and a 2D scanning area covering the heart and liver was selected, using a topviewing digital receiver. Excitation and emission spots were raster scanned (22.7 watts) for 30 mins (25 sec/ scan) in 2 mm steps. ROIs, drawn around the heart and liver, were used to generate time-intensity curves representing fluorescence intensity as a function of time.

Improved psychomotor performance in aged mice fed diet high in antioxidants is associated with reduced ex vivo brain interleukin-6 production

Psychomotor performance is decreased in the aged. This study investigated the relationship between brain oxidative stress, interleukin-6 (IL-6) production by brain tissue ex vivo and psychomotor deficits during aging, and the effects of feeding an antioxidant-rich diet on ex vivo brain IL-6 production and motor function in aged mice. Male BALBc mice reared in SPF conditions and ranging in age from 3 to 24 months were studied. There was a precipitous decline in motor function after 12 months of age and an increase in brain lipid peroxidation and IL-6 production by coronal brain slices ex vivo. In another study, 12-month-old mice were fed diets formulated to provide a disparate range of antioxidants. At 18 months of age psychomotor coordination, motor learning, and ex vivo brain IL-6 production were evaluated. Mice fed an antioxidant-rich diet had improved psychomotor coordination compared to mice fed diet adequate or low in antioxidants. When mice were tested on successive days, only those fed adequate and high antioxidants exhibited motor learning. Analysis of IL-6 production by coronal brain slices indicated that as dietary antioxidants increased, IL-6 production decreased. Collectively, these data indicate that antioxidants improve psychomotor performance in aged mice, and suggest antioxidants may be useful for reducing brain IL-6 production, which has been shown to increase in aged mice.

Comparison of Early Postoperative Enteral Nutrients versus Chow on Colonic Anastomotic Healing in Normal Animals

We aimed to clarify the effects of different enteral nutrients (normal chow, complete balanced nutrition, elemental nutrition enriched with glutamine, immune-enhancing diet and fiber) on colonic anastomotic healing in the stress-free metabolic state. The study was carried out with 50 male Balb-C mice in five groups of 10 animals each. After transverse colon anastomosis, animals were fed with early enteral nutrients using normal chow (group 1), Ensure^® (group 2), Alitraq^® (group 3), Impact^® (group 4), and Benefiber Resource^® orange juice drink (group 5) for 7 days. There were no significant differences among the groups in bursting pressure (p > 0.05). There was no statistical difference in terms of hydroxyproline level among groups 1–3. The hydroxyproline levels of groups 4 and 5 were statistically higher than that of the control group (p < 0.05 for both comparisons). Under normal conditions without stress, we could not demonstrate the superior effects of early enteral feeding with specialized enteral preparations over normal diets on colonic anastomoses when the bursting pressures were compared.

Plasmodium chabaudi chabaudi chronic malaria and pathologies of the urogenital tract in male and female BALBc mice

BALB/c mice of both sexes were infected with a non-virulent strain of Plasmodium chabaudi chabaudi and any pathologies occurring in the urogenital tract and its accessory glands were investigated. Organs and tracts were removed from infected and control mice at 15, 40 and 100 days post-injection, weighed and processed for macroscopical and histological analyses. The relative weights of preputial, clitoral glands and testes were modified in infected mice during the 40 days following infection. The preputial glands show a marked hypotrophy at 15 days post-infection. The bladders of half of the infected female mice and a few infected male mice displayed a conspicuous haemoglobinuria and frequent interstitial cystitis that worsened throughout the experiment. Also, several chronic inflammatory reactions were detected in the prostates, preputial and clitoral glands up to 100 days post-infection. A probable cause of such a divergence in the characteristics of the infection and in the nature of the pathologies identified in infected male and female mice is the interaction between the infection and the immune and endocrine systems of the host. The cause of the pathologies and their consequences on the host condition are discussed.

Alterations in resistin expression after thermal injury.

Burn injury, it was hypothesized, may induce changes in resistin expression that contribute to postburn metabolic derangements. This study examined resistin gene expression, serum levels of resistin protein, and glucose levels in burned mice. Ten male Balb-c mice were anesthetized and then given a 30% total burn surface area using heated probes. Burned and sham-burned mice were killed at 2, 4, 24, and 48 hours. The total ribonucleic acid from gonadal fat tissues was isolated for the measurement of resistin gene expression using real-time reverse transcriptase-polymerase chain reaction. Serum levels of resistin, insulin, and glucose were measured. Statistical analysis was performed by two-way analysis of variance using Bonferroni's test to find differences between groups. All p values less than 0.05 were considered significant. Increases in resistin gene expression and serum resistin levels were detected in the burned animals, and these correlated with relative insulin resistance. The findings suggest a potential role for resistin in the pathophysiology of the metabolic response to injury.

Performance of a Portable Whole-Body Mouse Exposure System

A mobile whole-body exposure system was developed for exposing mice to concentrated ambient particulate matter smaller than 2.5 μm in mass median aerodynamic diameter (MMAD). Each 20-L exposure cage was designed to hold 9 mice within individual compartments. This allowed for transport and subsequent exposure. Airflow mixing and the potential for stagnant areas within the compartments were modeled using computational fluid dynamic modeling (CFD). CFD analysis showed no stagnant areas and good mixing throughout the exposure cage. The actual performance of the exposure system was determined for 0.5 to 2.0 μm diameter aerosols by measuring (1) uniformity of aerosol distribution and (2) particle deposition in the tracheobronchial and pulmonary regions of mice exposed in the system. A 0.6-μm MMAD (GSD = 2.0) cigarette smoke aerosol was used to experimentally measure the uniformity of aerosol distribution to the nine individual compartments. The average data from three runs showed no statistically significant difference among individual compartments. Particle deposition efficiency in adult male BALB/c mice was measured after exposure (30 min) in the system using monodisperse fluorescent polystyrene latex particles (0.5, 1, and 2 μm aerodynamic diameter). The measured deposition efficiency in this mobile exposure system for the combined tracheobronchial and pulmonary regions of the adult male BALBc mice was 21% for 0.5 μm, 11% for 1.0 μm, and 6.5% for 2.0 μm particles. These deposition efficiencies are similar to those reported for mice exposed in a nose-only exposure system, which indicates that particle losses to animal fur and exposure system surfaces were acceptable.

Effect of dehydroleucodine on histamine and serotonin release from mast cells in the isolated mouse jejunum.

DhL, a lactone isolated from Artemisia douglasiana, prevents gastrointestinal damage elicited by necrosis-inducing agents and exhibits antiinflammatory action. This work examines the effect of DhL on compound 48/80-induced histamine and serotonin release in the isolated mouse jejunum, to determine whether DhL inhibits mediator release from mast cells at the enteric level. Thirty jejuna from male Balb-c mice were used for the studies. Samples were incubated sequentially in 9 test tubes containing RBS or 10 microg/ml compound 48/80 or 1.6 mmol/l + 10 microg/ml compound 48/80 at 37 degrees C for 90 minutes (10 min per tube). Histamine and serotonin release studies, quantification of granulated mast cells, and evaluation of mast cell ultrastructure were carried out. Differences between groups were determined using analysis of variance followed by Tukey-Kramer multiple comparisons test. Compound 48/80 increased histamine and serotonin release by the tissue (141.95 +/- 62.58 pg/mg tissue vs basal 5.45 +/- 1.04, P<0.01 and 20.04 +/- 2.81 vs basal 9.24 +/- 1.56 ng/ mg tissue, P<0.01, respectively), decreased the number of granulated submucosal mast cells (0.077 +/- 0.0035 vs basal 0.14 +/- 0.015, P<0.05), and elicited evident granule ultrastructural changes. These effects were reduced by dehydroleucodine (19.51 +/- 7.88, P<0.01; 12.69 +/- 1, P<0.05 and 0.143 +/- 0.014, P<0.05, respectively). The lactone inhibits compound 48/80-induced histamine and serotonin release from mast cells in the isolated mouse jejunum.

Oral treatment of organophosphate poisoning in mice.

Organophosphates are used as pesticides, herbicides, and chemical warfare agents. Treatment of organophosphate poisoning is with intravenous atropine and pralidoxime in addition to supportive care. This study determined the efficacy of oral agents in preventing death from organophosphate poisoning. The organophosphate paraoxon (8 mg/kg) was used in a murine model with lethality at four and 24 hours as an end point. For oral treatment, 15 male Balbc mice were given either atropine sulfate (4 mg/kg), or a combination of atropine sulfate (4 mg/kg) with pralidoxime (100 mg/kg), by oral gavage. A control group of 22 mice received water by oral gavage. Chi-square analysis was used to compare results in the different groups. Of the control group, six of 22 survived to four hours after paraoxon exposure. Of the exposed animals treated with oral atropine, eight of 15 survived to four hours. Of the exposed animals treated with a combination of atropine and pralidoxime, 13 of 15 survived to four hours. All animals surviving to four hours survived to 24 hours. The increased survival of animals in the atropine group relative to the control group was not significant (p = 0.09). Survival was significant in the group treated with atropine and pralidoxime relative to atropine alone (p = 0.02) and to the control group (p = 0.0002). All treated mice surviving at four hours were alive at 24 hours. Both oral atropine and a combination of oral atropine and pralidoxime improved survival, and combination therapy achieved statistical significance. Generalization of this result to other organophosphate pesticides, other doses of paraoxon, and other species cannot be made without further investigations.

Oral Treatment of Organophosphate Poisoning in Mice

Abstract Objective: Organophosphates are used as pesticides, herbicides, and chemical warfare agents. Treatment of organophosphate poisoning is with intravenous atropine and pralidoxime in addition to supportive care. This study determined the efficacy of oral agents in preventing death from organophosphate poisoning. Methods: The organophosphate paraoxon (8 mg/kg) was used in a murine model with lethality at four and 24 hours as an end point. For oral treatment, 15 male Balbc mice were given either atropine sulfate (4 mg/kg), or a combination of atropine sulfate (4 mg/kg) with pralidoxime (100 mg/kg), by oral gavage. A control group of 22 mice received water by oral gavage. Chi‐square analysis was used to compare results in the different groups. Results: Of the control group, six of 22 survived to four hours after paraoxon exposure. Of the exposed animals treated with oral atropine, eight of 15 survived to four hours. Of the exposed animals treated with a combination of atropine and pralidoxime, 13 of 15 survived to four hours. All animals surviving to four hours survived to 24 hours. The increased survival of animals in the atropine group relative to the control group was not significant (p = 0.09). Survival was significant in the group treated with atropine and pralidoxime relative to atropine alone (p = 0.02) and to the control group (p = 0.0002). All treated mice surviving at four hours were alive at 24 hours. Conclusions: Both oral atropine and a combination of oral atropine and pralidoxime improved survival, and combination therapy achieved statistical significance. Generalization of this result to other organophosphate pesticides, other doses of paraoxon, and other species cannot be made without further investigations.

In vivo pachymetry in normal eyes of rats, mice and rabbits with the optical low coherence reflectometer

The aim of this study was to determine the central corneal thickness (CCT) in living rats, mice and rabbits using a non-contact, high-speed optical low coherence reflectometer (OLCR) mounted on a regular slit lamp. Both eyes of eight male Wistar rats, eight male balb-c mice and eight male Japanese rabbits were measured. Each eye was measured twice (one measurement consists of 20 scans), the average calculated. Additionally, CCT was measured in rabbits using an ultrasound pachymeter. The mean CCT was: rats: 159.08 μm (SD±14.99 μm), mice: 106.0 μm (SD±3.45 μm) and rabbits: 356.11 μm (SD±14.34 μm). With the use of OLCR we were able to accurately measure the CCT of rats, mice and rabbits in vivo. This technique may prove useful in further refractive, pharmacological and glaucoma studies.

Light-induced Photoreceptor Apoptosis in vivo is Caspase Independent and Mediated by Nitric Oxide

INTRODUCTION. Retinitis pigmentosa (RP) is a genetically diverse disease, characterized by the progressive degeneration of rod and cone photoreceptors. Photoreceptor loss in RP occurs via apoptosis, a mode of programmed cell death, which allows a cell to partake in its own demise. Apoptosis therefore represents a common final pathway in the pathology of RP. However, the molecular events regulating photoreceptor apoptosis in human cases and animal models of RP remain undefined. In this study, we delineate the molecular events occurring during photoreceptor apoptosis in the light-induced retinal injury model of RP. METHODS. Retinal light damage: Adult male balb-c mice were exposed to 2 hours of cool white fluorescent light at a luminescence level of 5000 lux. Intraperitoneal injections: Mice were injected intraperitoneally with 100mgkg -1 of N G -nitro-L-arginine methyl ester (L-NAME) in phosphate buffered saline (PBS), or D-NAME (an inactive isomer) in PBS as a control, 1hr before light exposure. Flow cytometry was employed to monitor intracellular calcium levels, generation of reactive oxygen species and mitochondrial membrane depolarisation in untreated animals and in those treated with L-NAME. Caspase-3 activation was assessed by western blot and with the use of the synthetic substrate AcDEVD-pNA. The possible involvement of other caspases was assessed by treatment of the animals with ZVAD.fmk subretinally.

ORALLY ADMINISTERED ETHANE-1-HYDROXY-1,1-BIPHOSPHONATE REDUCES THE LETHAL EFFECT OF ORAL URANIUM POISONING

Intoxication with uranium compounds is both an occupational risk for the workers engaged in the different processes of the elaboration of nuclear fuel and a risk for the population at large in terms of contaminated water and food. The toxic effects of uranium can be reduced by the administration of a biphosphonate, ethane-1-hydroxy-1,1-biphosphonate (EHBP), subcutaneously or intraperitoneally. The aim of the present work was to examine whether orally administered EHBP reduces the lethal effect of a single orally administered toxic dose of uranyl nitrate. Nine groups of 20 male Balb-c mice were used. Five groups received 350 mg kg(-1) of uranyl nitrate orally administered by gavage, four were co-treated 20 min later with EHBP either by gavage (350, 500, or 700 mg kg(-1)) or by subcutaneous injection (50 mg kg(-1)), and one group was not treated. Four groups of animals received only EHBP in doses and routes the same as those used in the intoxicated animals. Survival was assessed for 14 d. On day 14 the surviving animals of all groups were killed. An additional group of uranium intoxicated animals was killed on day 2 after the start of the experiment. Kidneys were examined histologically. On day 3 all the animals treated with uranyl nitrate alone and 20% of the animals treated with 700 mg kg(-1) of EHBP alone were dead. Survival at day 14 of the groups of mice intoxicated with uranyl nitrate and treated with EHBP (50 mg kg(-1) orally or 50 mg kg(-1) subcutaneously) was 45.0 and 49.6%, respectively. Tubule necrosis lesions were present in kidneys of mice intoxicated with uranyl nitrate, whereas lesions were less severe in mice treated with EHBP. Oral administration of EHBP is effective for reducing the lethal effect of uranium, and it is at least as useful as subcutaneous administration for prompt therapy of oral uranium exposure, achieving a survival rate of almost 50%.

Bioavailability and pharmacokinetic parameters for 5-ethyl-2′-deoxyuridine

Pharmacokinetic parameters for 5-ethyl-2′-deoxyuridine (EDU) were determined following intravenous (iv) and oral (po) dosing in male Balb-C mice and iv dosing in male Sprague-Dawley rats. The concentrations of EDU in blood after 100 mg/kg iv bolus injections into mice and rats were consistent with a two compartment kinetic model. Based on this kinetic model, EDU showed a very short distribution half-life of 1.4 ± 0.7 min in mice and 1.3 ± 0.1 min in rats. The elimination half-life of EDU in rats following iv bolus injection, was substantially (18.5 ± 1.0 min) shorter than that in mice (24.1 ± 2.9 min). The mean residence time (MRT) of EDU was also substantially longer in mice (25.8 ± 4.9 min) compared to rats (11.0 ± 2.9 min). However, clearance of EDU was similar in both rats and mice. Although the biotransformation of EDU was similar in mice and rats, cleavage of the EDU glycoside bond was less extensive in mice than in rats. EDU showed a 49% bioavailability in mice after a 100 mg/kg po dose. The concentration of EDU in blood after a po dose provided the best fit to a one compartment model. The maximum blood concentration of EDU (C max) was 2.4 ± 0.2 μg/g of blood which attained 31.1 ± 1.2 min (T max) after a 100 mg/kg po dose. The AUC of 5-ethyluracil (EU) after a po dose of EDU was significantly higher ( P < 0.05) than after an iv dose of EDU. This observation indicates that EDU undergoes degradation by phosphorylases present in the gastrointestinal tract and/or by presystemic metabolism.

Intercellular adhesion molecule-1 contributes to pulmonary oxygen toxicity in mice: role of leukocytes revised.

In immature or injured lungs, impaired alveolar gas exchange forces the use of elevated levels of inhaled oxygen to maintain life. But, at high concentrations oxygen induces lung injury, edema, and bronchopulmonary dysplasia, probably by stimulating the generation of reactive oxygen radicals and subsequent neutrophil infiltration. In addition to regulating neutrophil diapedesis, intercellular adhesion molecule-1 (ICAM-1) expression is marked on inflamed alveolar epithelium, suggesting a role for ICAM-1 in oxygen-induced, neutrophil-mediated parenchymal damage. To test this, we evaluated the rat anti-mouse ICAM-1 monoclonal antibody YN1/1.7 in 2 protocols of oxygen-induced toxicity in adult, male Balb-c mice: greater than or equal to 95% O2 for 84 hr and greater than or equal to 95% O2 for 60 hr followed by 48 hr at 21% (ambient) O2. YN1/1.7 treatment partially attenuated the neutrophil infiltration, lung damage (lavage lactate dehydrogenase [LDH] activity) and dysfunction (reductions in respiratory system compliance [Crs] and diffusion capacity of the lungs for carbon monoxide [DLCO] in the 84 hr exposure protocol. In the milder 60 hr exposure protocol, YN1/1.7 completely blocked the oxygen-induced lung dysfunction (reductions in Crs and DLco). These results confirm the contribution of leukocytes in the pathogenesis of pulmonary oxygen toxicity and indicate that antagonism of ICAM-1 may provide a therapeutic approach to reducing hyperoxic lung injury and dysfunction.