Neurokinin-1 receptor antagonist inhibits short-term sulfuric-acid-induced airway hyperresponsiveness in sensitized guinea pigs

BACKGROUND

Tachykinins are involved in the development of bronchial inflammation and airway hyperresponsiveness (AHR); however, the role of the neurokinin-1 (NK(1)) receptor in acid-aerosol-induced bronchial impairment in asthmatic patients remains controversial.

METHODS

To investigate the effects on the NK(1) receptor antagonist FK888 the neurokinin-2 (NK(2)) receptor antagonist SR48968 on sulfuric-acid (H(2)SO(4))-induced AHR in guinea pigs, specific airways resistance (sRaw) and airways responsiveness to methacholine (MCh) were measured before and after 6 h of exposure to H(2)SO(4) aerosol (pH 1.7, 82 mg/m(3)) in ovalbumin-sensitized guinea pigs.

RESULTS

Airway responsiveness to MCh significantly increased (p<0. 05) after the exposure, however sRaw did not. Treatment with FK888 significantly inhibited (p<0.05) H(2)SO(4)-induced AHR in a dose-dependent manner, as did SR48968.

CONCLUSIONS

These results suggest that not only NK(2) but also NK(1) receptors might have important roles in the development of acid-aerosol-induced AHR.

[A case of very late onset overlap syndrome of systemic sclerosis and systemic lupus erythematosus]

A 88-year-old woman was admitted with appetite loss and dehydration in April 1999. She first noticed finger swelling in May 1996 and systemic sclerosis (SSc) was diagnosed in February 1997 on the basis of a clinical picture of low-grade fever, diffuse skin thickening, Raynaud's phenomenon, and pulmonary fibrosis. Retrospectively pulmonary fibrosis could have been identified on chest X ray film in September 1995. Although her appetite loss and dehydration were improved by hydration, pleural effusion continued. After detailed examinations, anti-topoisomerase 1 (Scl-70) antibody, anti-Sm antibody, and an anti-double-stranded DNA antibody (dsDNA) were found in her serum. However, the other antibodies to anti-SS-A, SS-B, Jo-1, and RNP were not detected. These results suggest that this elderly case was a very late onset overlap syndrome of systemic lupus erythematosus (SLE) and SSc. Thus, the pleural effusion in this case may have been caused by SLE-associated pleuritis. Although the late onset elderly cases with overlap syndrome are very rare, SLE, SSc, and their combination can be found in aged patients over 80 years old. SLE and SSc should be carefully considered for the differential diagnosis of pleural effusion and skin thickening even in elderly patients.

Effects of angiotensin-converting enzyme (ACE) inhibitors on oxygen radical production and generation by murine lung alveolar macrophages

We examined the effect of angiotensin-converting enzyme (ACE) inhibitors on oxygen radical production before and generation after phorbol-myristate acetate (PMA) stimulation of lung alveolar macrophages. Lung free cells, predominantly pulmonary alveolar macrophages, were obtained from Fischer 344 rats and guinea pigs using bronchoalveolar lavage. The oxygen radicals produced by pulmonary alveolar macrophages with or without stimulation of PMA were measured by lucigenin-dependent chemiluminescence method using a photon counter, Lumat 9501 (Berthold, Germany). Alacepril, an ACE inhibitor with SH-group, inhibited the oxygen radical production and generation by lung alveolar macrophages harvested from both rats and guinea pigs in a dose-dependent fashion. Approximately 0.3 mM of alacepril inhibited 50% of oxygen radical production of lung alveolar macrophages in both rats and guinea pigs, whereas a higher concentration (1-5 mM) of lisinopril, an ACE inhibitor without SH-group, was necessary to inhibit 50% of oxygen radical production of lung alveolar macrophages in the animals. These results suggest that an ACE inhibitor with SH-group acts as an antioxidant in murine lungs and the treatment with the ACE inhibitor may reduce oxidant stress in hypertensive patients with asthma.

Can urinary eicosanoids be a potential predictive marker of clinical response to thromboxane A2 receptor antagonist in asthmatic patients?

Thromboxane (TX) A2 is an important bronchoconstrictor in the pathogenesis of asthma. Seratrodast, known as AA-2414, is a new oral TXA2 receptor antagonist which is currently prescribed in asthma therapy in Japan. However its clinical effects have been very different in individual subjects. To assess whether the clinical efficacy of TXA2 antagonist is predictable on the basis of urinary arachidonic acid metabolites in urine of patients with asthma, an open and multicentre trial was conducted. Fifty adult asthmatic subjects (women/men = 28/22) were enrolled [resting mean forced expiratory volume in 1 sec (FEV1)% was 82%; range, 50-96%]. Urinary levels of 11-dehydro-TXB2, leukotriene (LT) E4, 2,3-dinor-6-keto-prostaglandin F1alpha and creatinine in 3-h urine collected in the morning at the start of seratrodast (80 mg day(-1), once a day at evening for 4 weeks) were measured. Responders were defined by improvements of asthma symptoms score and peak expiratory flow rate (PEFR). Of the 50 subjects, 45 completed this study. Eighteen patients were responders and the other 27 were nonresponders. There were no significant differences between the two groups in patients' characteristics, baseline lung functions, treatments and baseline urinary eicosanoids. The 11-dehydro-TXB2/LTE4 ratio of responders was significantly higher (P = 0.0091) than that of non-responders (mean +/- SE, 7.49+/-0.71 vs. 5.09+/-0.67). Eleven patients out of 18 responders agreed to continue this drug for 6 months, the 11-dehydro-TXB2/LTE4 ratio decreased during this period, but not significantly. Our data demonstrated that responders and non-responders to TXA2 receptor antagonist existed in patients with asthma, and it suggests that the ratio of urinary eicosanoids might be a possible predictor of the effects of TXA2 receptor antagonist.

[Small cell lung cancer associated with paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome]

A 57-year-old man was admitted to our hospital in November 1997 because of dysarthria, progressive ataxia, generalized weakness, and incoordination in both hands. He had been aware of the dysarthria 6 months earlier. Chest roentgenograms and computed tomographic films disclosed a 5 cm x 6 cm mass in the left S3b. The patient was given a diagnosis of small cell lung cancer (T3N2M0, stage IIIA) associated with paraneoplastic cerebellar degeneration (PCD). Three courses of chemotherapy (carboplatin and etoposide) eliminated the tumor and slightly alleviated the PCD symptoms. In March 1998, electromyograms revealed a fall in the single-stimulated M wave and a waxing phenomenon that had not been observed on admission. Anti-P/Q type voltage gated calcium channel antibody was detected in serum samples obtained on admission and after chemotherapy. These findings confirmed an association with Lambert-Eaton myasthenic syndrome. No relapse of the tumor has been observed 15 months after the last course of chemotherapy.

Mechanisms of action of OPC-28326, a selective hindlimb vasodilator

The unique cardiovascular profile of OPC-28326 [4-(N-methyl-2-phenylethylamino)-1-(3, 5-dimethyl-4-propionylaminobenzoyl)piperidine hydrochloride monohydrate] provides insight into basic mechanisms of this new drug as determined by experiments in dogs and rats. In anesthetized open-chest dogs, an i.v. administration of a low dose (0.3 and 1.0 microg/kg) of OPC-28326 selectively increased femoral artery blood flow with only minimal action on systemic blood pressure, heart rate and coronary, carotid, vertebral, renal, and mesenteric blood flows. Biochemical study suggests that OPC-28326 had no effect on phosphodiesterase-3 and -5. OPC-28326 dose-dependently inhibited phenylephrine-induced increases in blood pressure in spinally anesthetized dogs. The potency of OPC-28326 was, however, about 180 times lower than that of prazosin. Although binding studies have revealed an affinity of OPC-28326 to serotonin 5-HT(2) receptors, the drug is without effect, except at very high concentrations, on serotonin-induced contraction in an isolated canine femoral artery preparation. The potency of OPC-28326 on the increase in femoral artery blood flow was about 14 times higher than that of prazosin but was at about the same level as that obtained with yohimbine in canine autoperfused femoral artery preparations. In perfused rat hindlimb preparations, OPC-28326 inhibited the decrease in perfusion flow induced by brimonidine, a selective alpha(2)-adrenoceptor agonist. The potency of OPC-28326 was at least 10 times less than that of yohimbine. Taken together, the results show that at low doses, OPC-28326 selectively exerts a potent vasodilating effect on the femoral arterial bed, in part due to an alpha(2)-adrenoceptor-blocking activity.

Influence of age on diurnal variability in measurements of spirometric indices and respiratory pressures

We evaluated variations in spirometric indices (i.e., forced vital capacity [FVC], peak expiratory flow [PEF], and forced expiratory volume in 1 sec [FEV1]) and static respiratory muscle pressures (i.e., maximum static inspiratory pressure [PImax] and maximum static expiratory pressure [PEmax]) within a span of 12 hr in 60 healthy elderly subjects, 60 young subjects, and 30 Chronic Obstructive Pulmonary disease (COPD) patients. There were no differences among data of FVC, PEF, FEV1, PImax, and PEmax on three separate occasions within a day in the elderly or the young. The mean coefficient of variation (CV) values of PEF and PImax on three occasions were 3.0 +/- 0.3% and 4.2 +/- 0.4% in the elderly, and 2.4 +/- 0.2% and 3.7 +/- 0.3% in the young, respectively. No subjects had more than 9% CV on each measurement in the study, suggesting that there is nosignificant daytime variation in measurement of expiratory flow and respiratory pressures in young and elderly people. However, FVC, PEF FEV1, and PImax values in the morning were smaller than those measured at the other two occasions in COPD patients. The results indicate that COPD affects diurnal variation in pulmonary function, but age alone has little impact on diurnal variation.

Effects of ambroxol on spontaneous or stimulated generation of reactive oxygen species by bronchoalveolar lavage cells harvested from patients with or without chronic obstructive pulmonary diseases

We examined the effects of ambroxol on spontaneous or stimulated generation of reactive oxygen species (ROS) by bronchoalveolar lavage (BAL) cells prepared from 6 patients with chronic obstructive pulmonary disease (COPD) and age-matched control subjects without COPD. The ROS produced by BAL cells were measured by the lucigenin-dependent chemiluminescence method. The application of ambroxol into culture media containing BAL cells inhibited spontaneous and stimulated generation of ROS by BAL cells harvested from COPD patients and control subjects in an ambroxol concentration-dependent manner. These results indicate that ambroxol may be a candidate agent for reducing oxidant stresses of airways in COPD.

[Current strategy of bronchodilator therapy for chronic obstructive pulmonary disease (COPD)]

The COPD is slowly but progressive disease, the main purpose of the treatment for COPD is considered to produce a significant bronchodilating effect for maintaining lung functions for long period. Inhaled anticholinergic drug is currently used as the first-line therapy of patients with COPD. The beta 2-adrenergic agonists used be the other choice of bronchodilator for treatment of COPD. The benefit of inhalational steroid on the treatment of COPD is still a matter of debate. The accurate procedure of inhalational device and appropriate use of spacer are particularly important for older patients with COPD. The older patients with COPD can be better treated by the inhaled anticholinergic drug or its combination with beta 2-adrenergic agents.

Recombinant E1-deleted adenoviral vectors induce apoptosis in a rat airway epithelial mucous goblet cell line

Replication-defective adenoviruses (Ad) are used as vectors for delivering therapeutic genes to human airway cells. We examined whether E1-deleted Ad vectors (Ad5-CMV-LacZ) had effects on cell kinetics in SPOC1 cells, which is a rat airway epithelial mucous goblet cell line. There was a vector multiplicity of infection (moi)-dependent increase of the transduction efficiency of the LacZ reporter gene in SPOC cells. Cell proliferation was inhibited in the vector-infected cells compared with that in vehicle-exposed cells. However, increased cell death was observed in the vector-infected cells with a higher moi. The morphology of vector-exposed cells revealed apoptotic features including nuclear condensation and a fragmented nucleus. These results indicate that higher moi of vectors allows the cells to achieve higher gene transfer, but also induce apoptosis of infected cells. Minimizing the induction of apoptosis of vector-infected cells may be an important strategy for the prolongation of transduction efficiency of Ad vectors in airway epithelial mucous goblet cells.

Bilateral large peripapillary venous and arterial loops

BACKGROUND

Peripapillary loops of venous origin are extremely rare.

CASE

A 55-year-old woman was referred to us for further examination of peripapillary vascular abnormalities.

OBSERVATIONS

Fundus examination and fluorescein angiography clearly showed a venous and an arterial peripapillary loop in both her right and left fundi. The venous loop in the right eye was in a large hairpin configuration, extending into the retina about 1 disc diameter from the optic disc. Fluorescein angiography in the left eye revealed slow and irregular filling of dye into a venous loop that showed stasis of the bloodstream through the loop. Various retinal vascular abnormalities, including cilioretinal artery and triple branching of the retinal vein were also observed.

CONCLUSION

The findings in this case of bilateral peripapillary venous and arterial loops and unilateral trifurcation of retinal vein suggest that there could be an association in the other retinal abnormalities. Periodic follow-up examinations seem necessary.

[An elderly case with pseudogout exacerbated by the administration of granulocyte-colony stimulating factor during drug-induced granulocytopenia]

A 82-year-old woman was admitted because of dehydration and chronic renal failure. Although her renal function was improved by hydration, granulocytopenia (granulocyte number 645/mm3) occurred. Treatment with a relatively high dose of H2 blocker for one month before admission may have caused the granulocytopenia. To prevent possible infection in the patient, we administered 75 g of granulocyte-colony stimulating factor (G-CSF) for 5 consecutive days but 4 days after commencement of administration of G-CSF, pain in both knee joints suddenly appeared. Synovial fluid aspiration revealed granulocytosis (10,400/mm3) and deposition of calcium pyrophosphate dihydrate in the knee joints. The level of G-CSF in the synovial fluid was increased in the joints (700 pg/ml), compared with the serum concentration (62 pg/ml). Furthermore, the concentrations of interleukin-6 and interleukin-8 were markedly increased in the synovial fluid. The results indicated that her pseudogout exacerbation by G-CSF was at least in part explained by the increased production of cytokines in the knee joints. Because the prevalence of pseudogout and gout is overwhelming in the elderly, the possibility of GCSF induced exacerbation of joint pain should be carefully considered in elderly patients.

Glutathione S-transferase P1 (GSTP1) polymorphism in patients with chronic obstructive pulmonary disease

BACKGROUND

Enzymes that contribute to the local detoxification in alveoli and bronchioles have an important role in the defence mechanism against tobacco smoke. It has been suggested that genetic susceptibility to smoking injury may confer a risk for the development of chronic obstructive pulmonary disease (COPD). The polymorphisms in glutathione S-transferase P1 (GSTP1), a xenobiotic metabolising enzyme, were investigated in patients with COPD.

METHODS

Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) were performed to genotype GSTP1 polymorphisms in exon 5 (Ile105Val) and exon 6 (Ala114Val). Blood samples were taken from 53 patients with COPD and 50 control subjects at the Tokyo University Hospital, the Juntendo University Hospital, and the Tokyo Kenbikyoin Clinic for use in the study.

RESULTS

The proportion of GSTP1/Ile105 homozygotes was significantly higher in the patients with COPD than in the control subjects (79% vs 52%). The odds ratio for GSTP1/Ile105 homozygotes versus all other genotypes was 3.5 (95% CI 2.7 to 4.6) for COPD. Polymorphism at residue 114 of GSTP1 was not found in either group.

CONCLUSIONS

Genetic polymorphism of exon 5 of GSTP1 may be associated with COPD because the GSTP1/Ile105 genotype is predominantly found in COPD. It is suggested that the GSTP1/Ile105 genotype may be less protective against xenobiotics in tobacco smoke.