In vitro and in vivo assessment of plutonium speciation and decorporation in blood and target retention tissues after a systemic contamination followed by an early treatment with DTPA

This study identifies the main sources of systemic plutonium decorporated in the rat after DTPA i.v. at the dose recommended for humans (30 mumol kg(-1)). For this purpose, standard biokinetic approaches are combined to plasma ultrafiltration for separation of plutonium complexes according to their molecular weight. In vitro studies show that at the recommended DTPA dose, less than 5% of the plasma plutonium of contaminated rats can be displaced from high-molecular-weight ligands. After i.v. administration of Pu-DTPA, early ultrafiltrability of plutonium in plasma decreases with total DTPA dose, which is associated with an increase in plutonium bone retention. This demonstrates the instability of Pu-DTPA complexes, injected in vivo, below the minimal Ca-DTPA dose of 30 mumol kg(-1). Plutonium biokinetics is compared in rats contaminated by plutonium-citrate i.v. and treated or not with DTPA after 1 h. No significant decrease in plasma plutonium is observed for the first hour after treatment, and the fraction of low-molecular-weight plutonium in plasma is nearly constant [5.4% compared with 90% in Pu-DTPA i.v. (30 mumol kg(-1)) and 0.7% in controls]. Thus plutonium decorporation by DTPA is a slow process that mainly involves retention compartments other than the blood. Plutonium-ligand complexes formed during plutonium deposition in the retention organs appear to be the main source of decorporated plutonium.     

Application of a Four-fluid Nozzle Spray Drier to Prepare Inhalable Rifampicin-containing Mannitol Microparticles

The purpose of this study was to use a four-fluid nozzle spray drier as a new one-step method for preparing rifampicin (RFP)-containing mannitol microparticles. A RFP-acetone/methanol (2:1) solution and aqueous solutions of mannitol (MAN) were simultaneously supplied through different liquid passages of a four-fluid nozzle spray drier and then dried to obtain MAN microparticles containing RFP. Using a cascade impactor, the in vitro aerosol performance of RFP powder and RFP-MAN microparticles with 1:5, 1:10, and 1:20 ratios was compared. The in vivo retention of RFP in the lungs of rats after intratracheal administration of 1:20 RFP-MAN microparticles was also compared. The RFP-MAN microparticles had better aerosol performance than RFP powder and delivery to the lung stages improved as the fraction of MAN was increased. For the 1:20 RFP-MAN microparticles, deposition in stages 2–7 was approximately 43%, which is sufficient for treatment. Approximately 8% of the RFP-MAN microparticles were deposited in stages 6–7, which corresponds to alveoli containing alveolar macrophages. The initial retention of RFP in the lung following pulmonary delivery of 1:20 RFP-MAN microparticles was higher than following oral or intravenous administration of RFP, but the elimination was rapid, resulting in the disappearance of RFP from the lung within 4 h. The plasma concentration–time profile of RFP after intratracheal administration of 1:20 RFP-MAN microparticles was consistent with the profile for RFP retention in the lung. Addition of cholesterol or phosphatidylcholine to RFP had little effect on its retention in the lung. The RFP-MAN microparticles were effective for delivery of RFP to the lung, but the RFP rapidly removed from the lung into the blood circulation. This study demonstrated that RFP-containing MAN microparticles prepared in one step using the four-fluid nozzle spray drier efficiently deliver RFP to the lung, although methods must be developed to prolong its retention and improve targeting to alveolar macrophages.     

Efficacy of different DTPA treatment schedules for removal of 234Th from simulated wounds in rats

The translocation of 234Th from a simulated wound site and the efficacy of DTPA administration, as a function of the thorium compound injected as well as the DTPA treatment schedule, have been investigated in rats. Much more 234Th injected as citrate was translocated from the injection site than after administration as nitrate, whereas the distribution pattern of 234Th translocated to the various tissues was nearly identical for both 234Th compounds. Combined local and systematic treatment with DTPA was equally or more effective than each of the treatments alone in reducing the retention of 234Th at the injection site and in the organs.     

Chelation therapy of incorporated plutonium-238 and americium-241: comparison of LICAM(C), DTPA and DFOA in rats, hamsters and mice

The carboxylated catechoylamide 3,4,3-LICAM(C) was tested for removal of 238Pu and 241Am from small laboratory rodents. The effectiveness of treatment was compared with that of two ligand preparations approved for clinical use: calcium-trisodium diethylenetriaminepentaacetate (DTPA) and desferrioxamine (DFOA). With early treatment and at the dosage used clinically for the decorporation of actinides with DTPA (30 mumol/kg body weight) LICAM(C) was superior to DFOA but when compared with DTPA, the effect of LICAM(C) on 238Pu was greater only in bone; as little as 1 mumol LICAM(C)/kg was as effective as 30 mumol DTPA/kg. However, in all animals treated with LICAM(C) there was a large increase in the 238Pu content of the kidney. With 241Am the effect of DTPA was always superior to that of LICAM(C). The best overall results early (1 day) after injection of 238Pu and 241Am were achieved by a combination of a single injection of LICAM(C) and DTPA with subsequent continuous administration of DTPA in drinking water. LICAM(C) affected the retention of 238Pu even if given orally; the data suggested that about 3 per cent of ingested LICAM(C) was absorbed. When the beginning of treatment was delayed, LICAM(C) became equally effective or less effective than DTPA even as far as 238Pu retention in bone was concerned, but it still increased the accumulation of 238Pu in the kidneys.     

Protective effect of alpha-human atrial natriuretic polypeptide (alpha-hANP) on chemical-induced pulmonary edema

It has been established that alpha-hANP, the newly discovered peptide extracted from human cardiac atria, has potent natriuretic and hypotensive actions. Our present investigation is the first to demonstrate that alpha-hANP is capable of protecting against pulmonary edema caused by various chemicals, using isolated perfused guinea pig lung system. Lungs were perfused via pulmonary artery with Krebs-Ringer bicarbonate buffer at 5.0 ml/min, and wet weight of lungs and perfusion pressure of pulmonary artery (Pa) were monitored. Bolus injection of Triton-X or CHAPS into cannulated pulmonary artery produced edema as indicated by a massive increase in wet weight and a slight increase in Pa. Constant infusion of alpha-hANP through pulmonary artery at 200 ng/ml was effective in causing decrease in wet weight of lung. Perfusion of lung with paraquat or PGF2 alpha, and repeated bolus injection of arachidonic acid or PGE2 caused elevation in both wet weight of lung and Pa. The treatment with alpha-hANP similar to that described above also protected against edema caused by paraquat or arachidonic acid. Bolus administration of epinephrine induced a slight increase in wet weight and Pa, and alpha-hANP was effective in decreasing the elevated lung wet weight and Pa of lungs. Infusion or bolus administration of alpha-hANP into control lungs increased cGMP level in outflow perfusate as well as in lung tissue significantly. In lungs with edema which were induced by Triton-X or paraquat, there was a slight increase in cGMP level in Triton-X treated and no increase in paraquat treated lung tissues. In either cases, was there any increase in cGMP level in perfusate. The specific binding study of [125I]alpha-hANP revealed that the lack of increase in cGMP was not due to a loss of receptor in Triton-X or paraquat treated lungs. Thus our study demonstrated that alpha-hANP had a direct anti-edematic action(s) in lung which was not secondary to the systemic natriuretic and/or hypotensive action(s).     

Reducing the radiation dose from inhaled americium-241 using continuously administered DTPA therapy

Accelerating the removal of a radionuclide from the body of a contaminated individual is the only available approach to decreasing the radiation dose from such exposures. In this study, continuous infusion of a chelating agent, DTPA, was given to dogs that had inhaled a moderately soluble aerosol, 241 AmO2, not only to accelerate clearance of the radionuclide from the lung but also to prevent its deposition in liver and bone. Treatment was begun with an intravenous injection of CaDTPA 1 h after exposure, and was continued for 64 days after exposure by implanting subcutaneously osmotic pumps containing ZnDTPA at 1 day after exposure. The results showed that the infusion therapy was effective in blocking the translocation of 99.5 per cent of the 241Am that would have been deposited in liver, and 98.3 per cent of the 241Am that would have been deposited in bone. This result was significantly better than the result achieved using repeated intravenous injections of DTPA, the method of treatment in current use for actinide contamination cases.     

PECAM-directed delivery of catalase to endothelium protects against pulmonary vascular oxidative stress

Targeted delivery of drugs to vascular endothelium promises more effective and specific therapies in many disease conditions, including acute lung injury (ALI). This study evaluates the therapeutic effect of drug targeting to PECAM (platelet/endothelial cell adhesion molecule-1) in vivo in the context of pulmonary oxidative stress. Endothelial injury by reactive oxygen species (e.g., H2O2) is involved in many disease conditions, including ALI/acute respiratory distress syndrome and ischemia-reperfusion. To optimize delivery of antioxidant therapeutics, we conjugated catalase with PECAM antibodies and tested properties of anti-PECAM/catalase conjugates in cell culture and mice. Anti-PECAM/catalase, but not an IgG/catalase counterpart, bound specifically to PECAM-expressing cells, augmented their H2O2-degrading capacity, and protected them against H2O2 toxicity. Anti-PECAM/catalase, but not IgG/catalase, rapidly accumulated in the lungs after intravenous injection in mice, where it was confined to the pulmonary endothelium. To test its protective effect, we employed a murine model of oxidative lung injury induced by glucose oxidase coupled with thrombomodulin antibody (anti-TM/GOX). After intravenous injection in mice, anti-TM/GOX binds to pulmonary endothelium and produces H2O2, which causes lung injury and 100% lethality within 7 h. Coinjection of anti-PECAM/catalase protected against anti-TM/GOX-induced pulmonary oxidative stress, injury, and lethality, whereas polyethylene glycol catalase or IgG/catalase conjugates afforded only marginal protective effects. This result validates vascular immunotargeting as a prospective strategy for therapeutic interventions aimed at immediate protective effects, e.g., for augmentation of antioxidant defense in the pulmonary endothelium and treatment of ALI.     

Experimental studies of the translocation of plutonium from simulated wound sites in the rat.

Wound contamination with plutonium was simulated in rats by injection into either muscle or subcutaneous tissue. The distribution after the injection of plutonium nitrate indicated that: (i) clearance from the contaminated tissue was due mainly to the movement of soluble complexes of plutonium, principally to the skeleton and liver, but also involved slower movement of polymerized, particulate plutonium to lymph nodes; (ii) clearance of soluble plutonium, and hence the overall state of clearance, was dependent on the tissue fluid flow through the contiminated tissue and the mass of plutonium deposited; (iii) lymphatic clearance of particulate plutonium resulted in the release of some particles into the circulation and subsequent uptake by the liver. Intramuscular deposition of small plutonium dioxide particles (approximately 1 nm in diameter) resulted in a greater rate of clearance of plutonium than deposition of the nitrate. Although the solubility of these particles was evident from the level of skeletal uptake of plutonium, a high level of excretion indicated that some plutonium was filtered into the urine in an undissolved form.     

Distribution of plutonium in the body of rats after its intratracheal administration in the form of a Pu(IV)-TBP complex

Tributyl phosphate intratracheally administered to rat body with a Pu(IV)-TBP complex does not increase the accumulation of plutonium in the skeleton and liver. Plutonium is excreted from the lungs more readily than Pu(IV) nitrate and its large amounts are resorbed in the blood early after the administration; its excretion in feces is approximately 100 times more intense than in urine.     

Tackling COPD: a multicomponent disease driven by inflammation

In recent years, research has revealed more about the factors underlying the pathogenesis of chronic obstructive pulmonary disease (COPD). In particular, inflammation in the lungs leads to the structural changes observed in COPD, while extrapulmonary symptoms and comorbidities may be systemic manifestations of these inflammatory processes. A new multicomponent disease model is proposed that takes into account all elements that should be considered in treatment decisions. Current monotherapies act on different aspects of COPD and may not address all components. A combination of a long-acting beta2 agonist and an inhaled corticosteroid has complementary effects, addressing a wider range of components of COPD. This combination appears to have greater clinical benefits than either agent alone in reducing the frequency of exacerbations, reducing the number of hospitalizations, and potentially promoting survival. Minimizing the burden of COPD within--and potentially outside--the lung means treating patients early and addressing as many disease components as possible.     

The effect of X rays, DTPA, and aspirin on the absorption of plutonium from the gastrointestinal tract of rats

To measure the effect of radiation on plutonium transport, rats that were exposed to 250-kVp X rays were given 238Pu 3 days afterwards by either gavage or injection into a ligated segment of the duodenum. In a second group of experiments, rats were either injected intraduodenally with 238Pu-DTPA or administered the chelate intravenously and the 238Pu by gavage. In a third experiment, rats that had been gavaged with 200 or 400 mg/kg/day of aspirin for 2 days were injected intragastrically with 238Pu nitrate. Results of the first experiment showed a dose-dependent increase in 238Pu absorption between 800 and 1500 rad of lower-body X irradiation. Intravenous or intraduodenal injections of DTPA caused a marked increase in 238Pu absorption but resulted in decreased plutonium deposition in the skeleton and liver. Retention of 238Pu in the skeleton of rats given aspirin was double that of controls, but the effect on plutonium absorption was less marked than that of DTPA.     

A primary pulmonary sarcoma in a rhesus monkey after inhalation of plutonium dioxide

A pulmonary fibrosarcoma of bronchial origin was discovered in a Rhesus monkey that died of pulmonary fibrosis 9 years after inhalation of plutonium-239 dioxide and with a radiation dose to lung of 1400 rad (14 Gy). It grew around the major bronchus of the right cardiac lung lobe and extended into the bronchial lumen and into surrounding pulmonary parenchyma. It also readily invaded muscular pulmonary arteries, resulting in infarction and scarring in the right cardiac lobe. Despite this aggressive growth, the tumor did not metastasize. The primary cause of death was severe pulmonary fibrosis involving the alveolar septa and and perivascular and peribronchial interstitium. Bullous or pericitrical emphysema was prominent. The initial lung burden of plutonium in this monkey was 270 nCi (10 kBq) which is equivalent to approximately 500 times the maximum permissible lung burden for man on a radioactivity per unit body weight basis. The time-dose relationship for survival is consistent with that of dogs and baboons that inhaled plutonium dioxide and died with lung tumors.     

Pulmonary gemcitabine delivery for treating lung cancer: pharmacokinetics and acute lung injury aspects in animals

Gemcitabine, a nucleoside analogue for treating lung cancer, is clinically administered as an intravenous infusion. To achieve better patient compliance and more direct effect on the lung, we explored a new gemcitabine pulmonary delivery route and evaluated the pharmacokinetics and acute lung injury aspects in animals. Pharmacokinetics of gemcitabine were measured in Sprague-Dawley rats after intravenous (i.v.), intratracheal instillation by tracheotomy (i.t.t.), intratracheal instillation via orotrachea (i.t.o.), and intragastric (i.g.) administration of gemcitabine. Acute lung injury effects of the pulmonary delivery of gemcitabine were performed in Sprague-Dawley rats after i.t.o. and i.v. administration of gemcitabine and i.t.o. administration of lipopolysaccharide (LPS) as a positive control and physiological saline as a blank control. Indicators for acute lung injury that were evaluated included lung morphology, lung histopathology, lung coefficient, lung wet/dry weight ratio, total cell and classification counts in bronchoalveolar lavage cells (BALC), and total protein and TNF-alpha levels in bronchoalveolar lavage fluids (BALF). After i.t.t. or i.t.o. administration, gemcitabine was quickly absorbed, but i.g. administration led to an undetectable plasma gemcitabine concentration. Absolute bioavailability of gemcitabine after i.t.t. and i.t.o. administration was 91% and 65%, respectively. Gemcitabine given as i.t.o. administration did not cause any overt acute lung injury. All indicators for acute lung injury in the i.t.o. group were similar to those in the i.v. group or in the blank control, but significantly different from those in the positive control. In conclusion, the pharmacokinetics and acute lung injury studies suggest that pulmonary gemcitabine delivery would be a new and promising administration route.     

Adrenomedullin in the treatment of pulmonary hypertension

Adrenomedullin (AM) is a potent, long-lasting pulmonary vasodilator peptide. Plasma AM level is elevated in patients with primary pulmonary hypertension (PPH), and circulating AM is partially metabolized in the lungs. These findings suggest that AM plays an important role in the regulation of pulmonary vascular tone and vascular remodeling. We have demonstrated the effects of three types of AM delivery systems: intravenous administration, inhalation, and cell-based gene transfer. Despite endogenous production of AM, intravenously administered AM at a pharmacologic level decreased pulmonary vascular resistance in patients with PPH. Inhalation of AM improved hemodynamics with pulmonary selectivity and exercise capacity in patients with PPH. Cell-based AM gene transfer ameliorated pulmonary hypertension rats. These results suggest that additional administration of AM may be effective in patients with pulmonary hypertension. AM may be a promising endogenous peptide for the treatment of pulmonary hypertension.     

Potent effects of aerosol compared with intravenous treprostinil on the pulmonary circulation.

Inhaled vasodilator therapy for pulmonary hypertension may decrease the systemic side effects commonly observed with systemic administration. Inhaled medications only reach ventilated areas of the lung, so local vasodilation may improve ventilation-perfusion matching and oxygenation. We compared the effects of intravenous vs. aerosolized treprostinil on pulmonary and systemic hemodynamics in an unanesthetized sheep model of sustained acute pulmonary hypertension. Acute, stable pulmonary hypertension was induced in instrumented unanesthetized sheep by infusing a PGH(2) analog, U-44069. The sheep were then administered identical doses of treprostinil either intravenously or by aerosol. Systemic and pulmonary hemodynamics were recorded during each administration. Both intravenous and aerosol delivery of treprostinil reduced pulmonary vascular resistance and pulmonary arterial pressure, but the effect was significantly greater with aerosol delivery (P < 0.05). Aerosol delivery of treprostinil had minimal effects on systemic hemodynamics, whereas intravenous delivery increased heart rate and cardiac output and decreased left atrial pressure and systemic blood pressure. Aerosol delivery of the prostacyclin analog treprostinil has a greater vasodilatory effect in the lung with minimal alterations in systemic hemodynamics compared with intravenous delivery of the drug. We speculate that this may result from treprostinil stimulated production of vasodilatory mediators from pulmonary epithelium.     

FACTORS INFLUENCING THE EFFICIENCY OF LIPOPLEXES MEDIATED GENE TRANSFER IN LUNG AFTER INTRAVENOUS ADMINISTRATION*

The objectives of this study were to test the influence of different parameters on the in vivo cationic lipid mediated gene transfer in lung after intravenous administration. Luciferase activity was evaluated in lung tissue 24 hours after intravenous administration of different types of lipoplexes. These included lipoplexes prepared using cationic phosphonolipids or DOTAP and various amounts of plasmid DNA. Using two different plasmids we tested the influence of plasmid size on transfection efficiency in vivo. In a last series of experiments, lipoplexes were prepared using different excipients (water, NaCl or 5% glucose solution) and three injection volumes were tested. We demonstrate that chemical structure modifications such as cation substitution and increment of the aliphatic chain length significantly improve transfection efficiency. High luciferase levels are obtained by increasing lipid to DNA charge ratio and plasmid DNA dose and decreasing plasmid size. Lipoplexes prepared in physiological NaCl solution and injected using a volume of 800μl are significantly the most effective.

Cationic lipid mediated gene transfer in lung tissue after intravenous administration is influenced by factors including cationic lipid chemical structure, lipid to DNA ratio and plasmid dose. Nevertheless, plasmid size, injection volume and the excipient, used for the lipoplexes preparation, are also important factors and must be considered for an optimization of in vivo gene delivery using intravenous administration.     

Bioactive analogues and drug delivery systems of vasoactive intestinal peptide (VIP) for the treatment of asthma/COPD

Vasoactive intestinal peptide (VIP) is one of the major peptide transmitters in the central and peripheral nervous systems, being involved in a wide range of biological functions. In an airway system where VIP-immunoreactive nerve fibers are present, VIP acts as neurotransmitter or neuromodulator of the inhibitory non-adrenergic and non-cholinergic airway nervous system and influences many aspects of pulmonary biology. A clinical application of VIP has been believed to offer potential benefits in the treatment of chronic inflammatory lung diseases such as asthma and chronic obstructive pulmonary disease (COPD), however, its clinical application has been limited in the past for a number of reasons, including its extremely short plasma half-life after intravenous administration and difficulty in administration routes. The development of long-acting VIP analogues, in combination with appropriate drug delivery systems, may provide clinically useful agents for the treatment of asthma/COPD. In this review, development of efficacious VIP derivatives, drug delivery systems designed for VIPs and the potential application for asthma/COPD are discussed. We also include original data from our chemical modification experiments and formulation studies, which led to successful development of [R(15, 20, 21), L(17)]-VIP-GRR (IK312532), a potent VIP analogue, and a VIPs-based dry powder inhaler system.     

Aerosol gene therapy

Gene therapy is a novel field of medicine that holds tremendous therapeutic potential for a variety of human diseases. Targeting of therapeutic gene delivery vectors to the lungs can be beneficial for treatment of various pulmonary diseases such as lung cancer, cystic fibrosis, pulmonary hypertension, alpha-1 antitrypsin deficiency, and asthma. Inhalation therapy using formulations delivered as aerosols targets the lungs through the pulmonary airways. The instant access and the high ratio of the drug deposited within the lungs noninvasively are the major advantages of aerosol delivery over other routes of administration. Delivery of gene formulations via aerosols is a relatively new field, which is less than a decade old. However, in this short period of time significant developments in aerosol delivery systems and vectors have resulted in major advances toward potential applications for various pulmonary diseases. This article will review these advances and the potential future applications of aerosol gene therapy technology.     

Enhanced decorporation of plutonium by DTPA encapsulated in small PEG-coated liposomes

The aim of the study was to demonstrate that decorporation of 238Pu is achieved more efficiently by an optimized liposomal formulation of diethylene triamine pentaacetic acid (DTPA) than by the usual free DTPA treatment. The optimized formulation consisted of polyethylene glycol-coated stealth liposomes with a mean diameter of 100 nm (SL-100 nm). Rats were intravenously injected with various Pu-phytate salt solutions in order to test different contamination conditions (activity and salt concentration) impacting liver kinetics and skeletal uptake of Pu. All treatments were given intravenously 1 h after contamination. Efficiency was evaluated 24 h, 7, 16 or 30 days later through their ability to promote Pu elimination and to reduce Pu burden in the skeleton and liver, the main organs of Pu deposition and radiotoxicological effects. Whatever the conditions of contaminations, a single injection of SL-100 nm (3.2 micromol kg(-1) DTPA) boosted urinary elimination of Pu to above 90% of the injected dose. In addition, liposomes strongly and significantly reduced the Pu burden of the liver and skeleton even 30 days after a single treatment: a dose of 0.3 micromol kg(-1) induced the same skeletal Pu reduction as four injections of free DTPA (30 micromol kg(-1)). A log dose-effect relation was found with SL-100 nm DTPA and Pu excretion in urine or Pu burden in the studied organs (liver, femurs, spleen and kidneys). This efficacy was attributed to an optimized targeting of DTPA to the main Pu retention organs and especially the liver.     

Effective chelation therapy after incorporation of neptunium-239 in rats

It was demonstrated in rats that it is possible to reduce the retention of 239Np in all body tissues by an early combined treatment with small doses of DTPA and DFOA. The content of 239Np can be decreased in soft tissues even if treatment is delayed. Promptly administered LICAM(C) proved more effective than the above chelate combination in reducing 239Np retention in the bones but increased that in the muscles and especially in the kidneys. This side effect of LICAM(C) could be partly prevented by simultaneous treatment with DTPA.