2-Aryl-3,3,3-trifluoro-2-hydroxypropionic acids: a new class of protein tyrosine phosphatase 1B inhibitors.

A new series of non-peptidic, mono-acid protein tyrosine phosphatase 1B (PTP1B) inhibitors has been identified by structure-based design. Compounds with 2-(indol-3-yl)- and 2-phenyl-3,3,3-trifluoro-2-hydroxypropionic acid core units targeted at the enzyme's primary site and a hydrophobic chlorophenylthiazole extension in its 2 degrees site exhibit 3-60microM IC(50)s for PTP1B inhibition in an Sf9 cell-based assay.

Sample characterization of automobile and forklift diesel exhaust particles and comparative pulmonary toxicity in mice.

Two samples of diesel exhaust particles (DEPs) predominate in health effects research: an automobile-derived DEP (A-DEP) sample and the National Institute of Standards Technology standard reference material (SRM 2975) generated from a forklift engine. A-DEPs have been tested extensively for their effects on pulmonary inflammation and exacerbation of allergic asthmalike responses. In contrast, SRM 2975 has been tested thoroughly for its genotoxicity. In the present study, we combined physical and chemical analyses of both DEP samples with pulmonary toxicity testing in CD-1 mice to compare the two materials and to make associations between their physicochemical properties and their biologic effects. A-DEPs had more than 10 times the amount of extractable organic material and less than one-sixth the amount of elemental carbon compared with SRM 2975. Aspiration of 100 micro g of either DEP sample in saline produced mild acute lung injury; however, A-DEPs induced macrophage influx and activation, whereas SRM 2975 enhanced polymorphonuclear cell inflammation. A-DEPs stimulated an increase in interleukin-6 (IL-6), tumor necrosis factor alpha, macrophage inhibitory protein-2, and the TH2 cytokine IL-5, whereas SRM 2975 only induced significant levels of IL-6. Fractionated organic extracts of the same quantity of DEPs (100 micro g) did not have a discernable effect on lung responses and will require further study. The disparate results obtained highlight the need for chemical, physical, and source characterization of particle samples under investigation. Multidisciplinary toxicity testing of diesel emissions derived from a variety of generation and collection conditions is required to meaningfully assess the health hazards associated with exposures to DEPs. Key words: automobile, diesel exhaust particles, forklift, mice, pulmonary toxicity, SRM 2975.

The effect of selective phosphodiesterase inhibitors, alone and in combination, on a murine model of allergic asthma.

BACKGROUND: The anti-inflammatory effects of the selective phosphodiesterase (PDE) inhibitors cilostazol (PDE 3), RO 20-1724 (PDE 4) and sildenafil (PDE 5) were examined in a murine model of allergic asthma. These compounds were used alone and in combination to determine any potential synergism, with dexamethasone included as a positive control. METHODS: Control and ovalbumin sensitised Balb/C mice were administered orally with each of the possible combinations of drugs at a dose of 3 mg/Kg for 10 days. RESULTS: When used alone, RO 20-1724 significantly reduced eosinophil influx into lungs and lowered tumour necrosis factor-alpha, interleukin-4 and interleukin-5 levels in the bronchoalveolar lavage fluid when compared to untreated mice. Treatment with cilostazol or sildenafil did not significantly inhibit any markers of inflammation measured. Combining any of these PDE inhibitors produced no additive or synergistic effects. Indeed, the anti-inflammatory effects of RO 20-1724 were attenuated by co-administration of either cilostazol or sildenafil. CONCLUSIONS: These results suggest that concurrent treatment with a PDE 3 and/or PDE 5 inhibitor will reduce the anti-inflammatory effectiveness of a PDE 4 inhibitor.

Differential pulmonary inflammation and in vitro cytotoxicity of size-fractionated fly ash particles from pulverized coal combustion.

Exposure to airborne particulate matter (PM) has been associated with adverse health effects in humans. Pulmonary inflammatory responses were examined in CD1 mice after intratracheal instillation of 25 or 100 microg of ultrafine (< 0.2 microm), fine (< 2.5 microm), and coarse (> 2.5 microm) coal fly ash from a combusted Montana subbituminous coal, and of fine and coarse fractions from a combusted western Kentucky bituminous coal. After 18 hr, the lungs were lavaged and the bronchoalveolar fluid was assessed for cellular influx, biochemical markers, and pro-inflammatory cytokines. The responses were compared with saline and endotoxin as negative and positive controls, respectively. On an equal-mass basis, the ultrafine particles from combusted Montana coal induced a higher degree of neutrophil inflammation and cytokine levels than did the fine or coarse PM. The western Kentucky fine PM caused a moderate degree of inflammation and protein levels in bronchoalveolar fluid that were higher than the Montana fine PM. Coarse PM did not produce any significant effects. In vitro experiments with rat alveolar macrophages showed that of the particles tested, only the Montana ultrafine displayed significant cytotoxicity. It is concluded that fly ash toxicity is inversely related with particle size and is associated with increased sulfur and trace element content.

Murine pulmonary inflammatory responses following instillation of size-fractionated ambient particulate matter.

The mechanisms for increased cardiopulmonary disease in individuals exposed to particulate air pollution are associated with fine and ultrafine particles that have a high oxidative potential. Particulate matter (PM) from Research Triangle Park (NC) was collected and separated into 3 different size fractions: coarse (CO; >3.5 microm), fine (FI; 1.7-3.5 microm), and fine/ultrafine (FU; <1.7 microm) using impaction and electrostatic precipitation. Particle chemistry indicated the presence of sulfates, zinc, iron, and copper in all fractions. CD1 mice were intratracheally instilled with 10, 50, or 100 microg of each fraction. After 18 h, the lungs were lavaged and assayed for signs of inflammation. All particles produced increases in neutrophil number, and this was highest in the high-dose FU group. Biochemical analysis revealed ni change in lactate dehydrogenase (LDH) activity, and increased albumin and tumor necrosis factor (TNF)-alpha levels were only seen with the high-dose FI particles. Interleukin 6 (IL-6) levels were increased over control levels after treatment with 100 microg of all 3 particle sizes. To determine whether oxidative stress may contribute to these effects, antioxidant levels in the ling were boosted by an intraperitoneal (ip) injection with dimethylthiourea (DMTU). This treatment resulted in a twofold increase in the total antioxidant capacity of the lung and decreased the PM-induced cytokine and neutrophil influx up to 50%. The data indicate that on the equal mass basis, ambient particles of these three size ranges produce pulmonary inflammation, and that increasing the antioxidant capacity of the lung reduces particle-induced cytokine and cellular responses.

The role of free radicals in the toxic and inflammatory effects of four different ultrafine particle types.

PM10 contains an ultrafine component, which is generally derived from combustion processes. This ultrafine fraction may be a factor in the increases in exacerbations of respiratory disease and deaths from cardiorespiratory causes associated with transient increases in levels of PM10. By using four different ultrafine particles (carbon black, cobalt, nickel, and titanium dioxide), we set out to determine the attributes of the ultrafine particle (surface area, chemical composition, particle number, or surface reactivity) that contribute most to its toxicity and proinflammatory effects both in vivo and in vitro. Instillation of 125 micro g ultrafine carbon black (UFCB) and ultrafine cobalt (UFCo) particles induced a significant influx of neutrophils at both 4 and 18 h postinstillation. Accompanying the influx of neutrophils was an increase in macrophage inflammatory protein-2 (MIP-2) (at 4 h) and an increase in gamma-glutamyl transpeptidase (at 18 h) in bronchoalveolar lavage fluid (BAL). Ultrafine nickel (UFNi) did not induce a significant increase in neutrophil influx until 18 h postinstillation. The increase in neutrophils induced by UFNi at this timepoint was comparable to that induced by UFCo and UFCB. UFTi did not induce a significant increase in neutrophils following instillation into the rat lung. The levels of MIP-2 observed at 4 h and neutrophil influx at 18 h induced by the particle samples were consistent with the pattern of surface free radical generation (as measured by the plasmid scission assay) whereby UFCo, UFCB, and UFNi all cause significant increases in inflammatory markers, as well as inducing a significant depletion of supercoiled plasmid DNA, indicative of hydroxyl radical generation. A role for free radicals and reactive oxygen species (ROS) in mediating ultrafine inflammation is further strengthened by the ability of the antioxidants N-acetylcysteine (NAC) and glutathione monoethyl ester (GSHme) to block the particle induced release of tumour necrosis factor-alpha (TNF-alpha) from alveolar macrophages in vitro. The ultrafine particles in PM10 may cause adverse effects via oxidative stress, and this could have implications for susceptible individuals. Susceptible individuals, such as those with COPD or asthma, already exhibit preexisting oxidative stress and hence are in a primed state for further oxidative stress induced by occupational or environmental particles.