Publications

We have previously shown that tachykinin depletion or antagonism prevented the increase in airway responsiveness to inhaled acetylcholine caused by exposure to toluene diisocyanate (TDI) in awake guinea pigs. To insure that the effects of tachykinins were not limited to the extrathoracic airways and were not dependent on effects of TDI on baseline airway caliber, we determined airway responsiveness to acetylcholine inhaled through a tracheostomy in anesthetized and ventilated guinea pigs that were exposed to TDI or air after treatment with the tachykinin antagonist spantide, the tachykinin metabolism inhibitor phosphoramidon, or the vehicles for each drug. When these drugs were administered before and during TDI exposure, spantide significantly inhibited the TDI-induced increase in acetylcholine responsiveness and phosphoramidon significantly potentiated this effect, whereas neither drug altered acetylcholine responsiveness in air-exposed animals. To determine whether tachykinins were exerting their effect primarily during TDI exposure or during the subsequent acetylcholine challenge, we also examined the effect of each drug on acetylcholine responsiveness when the drugs were given after TDI exposure. At that time, spantide did not inhibit TDI-induced acetylcholine hyperresponsiveness and phosphoramidon did not potentiate it. Neither drug nor TDI increased pulmonary resistance measured through a tracheostomy in these anesthetized and ventilated animals. These results suggest that the TDI-induced increase in acetylcholine responsiveness is mediated by release of tachykinins into the intrathoracic airways during exposure to TDI.

New brain imaging techniques may provide evidence for a biological basis for severe psychiatric disorders. The authors used quantitative X-ray computed tomography (CT) to analyze the brain volume of 10 male patients with severe primary obsessive-compulsive disorder and 10 healthy male control subjects. Caudate nucleus volume in the patients with obsessive-compulsive disorder was significantly less than that of control subjects, but lenticular nuclei, third ventricle, and lateral ventricle volumes did not differ between these two groups, and no abnormal asymmetry of bilateral structures was detected. These findings support other evidence of involvement of the caudate nucleus in obsessive-compulsive disorder.

The absolute bioavailability and dose proportionality of betaxolol [(+/-)-1-(p-[2-cyclopropylmethoxy)ethyl]phenoxy]-3- (isopropylamino)-2-propanol hydrochloride], a cardioselective beta-adrenergic antagonist effective in the treatment of angina and hypertension, was studied in 12 healthy male subjects using a four-way crossover Latin Square design. Each subject received a 10-mg iv dose administered by constant-rate infusion over a period of 30 min and three oral doses (10, 20, and 40 mg). Blood and urine were collected over a 48-h period and analyzed for betaxolol using gas-liquid chromatography with electron capture detection. Maximum concentrations occurred 3-4 h after the dose. The maximum mean (+/- SD) blood concentrations normalized to the 10-mg oral dose were 21.6 +/- 3.7, 21.1 +/- 3.7, and 22.5 +/- 4.0 micrograms/L following the 10-, 20-, and 40-mg doses, respectively. A significant lag time of 10-80 min was observed after oral doses but was not related to dose size. The terminal slope (ts), absolute bioavailability (F), and renal clearance (CLr) were likewise not affected to an important degree by dose (ts: 0.043 +/- 0.006, 0.044 +/- 0.005, 0.046 +/- 0.006 h-1; F: 0.88 +/- 0.08, 0.82 +/- 0.06, 0.84 +/- 0.07; CLr: 0.68 +/- 0.22, 0.69 +/- 0.19, 0.65 +/- 0.22 mL/min kg). Unlike many beta-adrenergic antagonists, betaxolol has a long half-life (13-20 h) and high and consistent bioavailability (70-90%), and its disposition is independent of the size of the administered dose.

An unusual family of cDNA clones homologous to human p55 IL-2R sequences was isolated from the murine HT-2 Th cell line. These clones were mapped, partially sequenced, and compared with previously published human and mouse IL-2R sequences. They appear to consist of various combinations of exons and introns, suggesting that they are derived from p55 IL-2R mRNA precursors. The configuration of exons in the splicing intermediates indicates that the murine and human gene organizations are similar and that the 3' end of intron 3 is well conserved between the two species. RNA mapping experiments using nuclear, cytoplasmic, and total RNA and probes derived from various parts of the p55 IL-2R gene support and extend the sequence data. They indicate that detectable amounts of immature p55 IL-2R mRNA are found specifically in the cell nucleus of the HT-2 cell line. Similar data were obtained for the Th cell clone 52.3 and the cytotoxic T cell line CTLL. All these results indicate that the T cell nucleus contains significant amounts of immature p55 IL-2R mRNA.