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A new wet limestone−gypsum process for flue gas desulfurization (FGD) has been developed. The main difference compared to a conventional wet FGD process is the ability of the new process to utilize granular limestone directly as a desulfurizing reagent. Thus, the pulverizing of limestone, which causes power consumption, can be avoided. The performance of the wet FGD process using granular limestone was confirmed to be equal to or higher than that of a conventional process in various tests. Tests were also performed in a 2000 m³Normal/h demonstration plant introducing actual flue gas of various types of coals at Matsuura Thermal Power Station of the Electric Power Development Co., Ltd. (EPDC) in Japan. It was also confirmed that the desulfurization performance of the granular limestone FGD process was not decreased by aluminum−fluorine-containing compounds in the absorbing slurry as much as in the pulverized limestone case. In this new wet FGD process, gypsum quality was also higher than that in a conventional wet FGD process.

The relationship between CD4⁺ T cell-mediated airway eosinophilic inflammation and bronchial hyper-responsiveness (BHR) was investigated. Ovalbumin-reactive T_h0 clones were adoptively transferred to unprimed BALB/c mice and then the mice were challenged by inhalation of the relevant antigen. Upon antigen provocation, infused T_h clones infiltrated into the airways, followed by the accumulation and degranulation of eosinophils, goblet cell hyperplasia, edema and increase in bronchial responsiveness to acetylcholine. Transfer of several clones that differed in the levels of IL-5 production revealed that the magnitude of in vivo eosinophilia strongly correlated with the IL-5-producing capacity of the infused T_h clones. Administration of anti-IL-5 mAb almost completely suppressed antigen-induced eosinophilic inflammation and BHR. Administration of anti-IL-4 mAb or anti-IFN-γ mAb enhanced the eosinophilia and BHR, whereas anti-IL-2 mAb did not affect them. The number of accumulated eosinophils significantly correlated with the intensity of BHR. Our present results clearly demonstrated that CD4⁺ T cells induced BHR as a result of eosinophilic inflammation. IL-5 totally regulated both responses.

The relationship between CD4(+) T cell-mediated airway eosinophilic inflammation and bronchial hyper-responsiveness (BHR) was investigated. Ovalbumin-reactive T(h)0 clones were adoptively transferred to unprimed BALB/c mice and then the mice were challenged by inhalation of the relevant antigen. Upon antigen provocation, infused T(h) clones infiltrated into the airways, followed by the accumulation and degranulation of eosinophils, goblet cell hyperplasia, edema and increase in bronchial responsiveness to acetylcholine. Transfer of several clones that differed in the levels of IL-5 production revealed that the magnitude of in vivo eosinophilia strongly correlated with the IL-5-producing capacity of the infused T(h) clones. Administration of anti-IL-5 mAb almost completely suppressed antigen-induced eosinophilic inflammation and BHR. Administration of anti-IL-4 mAb or anti-IFN-gamma mAb enhanced the eosinophilia and BHR, whereas anti-IL-2 mAb did not affect them. The number of accumulated eosinophils significantly correlated with the intensity of BHR. Our present results clearly demonstrated that CD4(+) T cells induced BHR as a result of eosinophilic inflammation. IL-5 totally regulated both responses.

The structural requirements for potent and selective PDE4 inhibition were revealed in a 1-pyridylnaphthalene series, and the best compound (3kg, T-2585·HCl) was chosen for further biological evaluation (PDE4 inhibition IC50 = 0.13 nM, selectivity PDE3/4 ratio = 14 000). Compound 3kg showed potent antispasmogenic activities (ED50 = 0.063 mg/kg for reduction of antigen-induced bronchoconstriction, intravenously; ED50 = 0.033 mg/kg for reduction of histamine-induced bronchoconstriction, intraduodenally) in guinea pigs with little cardiovascular effects. Furthermore, 3kg induced significantly weaker emetic effects than RP73401 after oral administration in ferrets and intravenous administration in dogs (3kg, none of 4 ferrets vomited at a dose of 10 mg/kg, po and none of 8 dogs vomited at a dose of 0.3 mg/kg, iv; RP73401, 4 of 8 ferrets vomited at a dose of 3 mg/kg, po and 6 of 8 dogs vomited at a dose of 0.3 mg/kg, iv); that is compatible with the lower affinity for the high-affinity rolipram binding site (3kg, 2.6 nM; RP73401, 0.85 nM). This may imply that 3kg has an improved therapeutic ratio because of a broad margin between the Ki value of binding affinity and the IC50 value of PDE4 inhibition (ratio = 0.050).

A series of 1-aryl-2,3-bis(hydroxymethyl)naphthalene lignans have been synthesized and evaluated for their ability to selectively inhibit PDE IV isolated from guinea pig. Replacement of the 1-phenyl ring by a pyridone ring led to marked improvement of their selectivity for PDE IV over PDE III. The compounds that were most potent and selective involved those bearing an N-alkylpyridone ring at C-1. These compounds also showed potent antispasmogenic activity without causing significant changes in heart rate in the guinea pig. The most potent compound was 6,7-diethoxy-2,3-bis(hydroxymethyl)-1-[1-(2-methoxyethyl)-2-oxo-pyrid-4-yl]naphthalene (17f), ED50 values of histamine-induced and antigen-induced bronchoconstriction in the guinea pig being 0.08 and 2.3 mg/kg iv, respectively. This compound was chosen as a candidate for further pharmacological evaluation.