Imipramine-induced inactivation of a cytochrome P450 2D enzyme in rat liver microsomes: in relation to covalent binding of its reactive intermediate

Preincubation of microsomes from male Wistar rats with imipramine (IMI) in the presence of NADPH caused a time-dependent loss of bunitrolol 4-hydroxylase activity, indicating that the CYP2D enzyme is inactivated during IMI metabolism, which has also been observed after in vivo administration of IMI. A similar effect was obtained when desipramine, an N-demethylated metabolite of IMI, was used as an inhibitor, whereas 2-hydroxy-IMI had no effect on the activity. Thus, it seems likely that the inactivation of the CYP2D enzyme is related to 2-hydroxylation process of IMI. Incubation of microsomes with [3H]IMI in the presence of NADPH resulted in covalent binding of a 3H-labeled material to microsomal protein. Formation rates of the reactive metabolites covalently bound to protein followed Michaelis-Menten kinetics, and the K(m) value (1.1 microM) was close to that for microsomal IMI 2-hydroxylation. The metabolism-dependent covalent binding of [3H]IMI was lower in Dark Agouti rats, which is an animal model of CYP2D deficiency, than in Wistar rats. The binding was inhibited by propranolol and quinidine, a substrate and an inhibitor of CYP2D, respectively, and by an antibody against CYP2D. Similar strain difference (Dark Agouti < Wistar) and inhibitory effects by the compounds and the antibody were observed in IMI 2-hydroxylase but not in N-demethylase activity. SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) of microsomal protein incubated with [3H]IMI and NADPH showed that the binding was prominent at the molecular mass of approximately 50 kDa, which would be consistent with the P450 protein being a target for the binding. Furthermore, proteins to which [3H]IMI metabolites covalently bound were immunoprecipitated with the anti-CYP2D antibody. These results suggest that IMI is biotransformed into a chemically reactive metabolite (probably arene-oxide) through its 2-hydroxylation step by the CYP2D enzyme in rat liver microsomes, and the metabolite binds covalently to the enzyme itself, resulting in the inactivation.

Stereoselectivity in bunitrolol 4-hydroxylation in liver microsomes from marmosets and Japanese monkeys

The stereoselectivity in 4-hydroxylation of bunitrolol (BTL), a beta-adrenoreceptor blocking agent, was examined in liver microsomes from monkeys (marmosets and Japanese monkeys) and compared with the results of human liver microsomes. The formation of (+)-4-OH-BTL from (+)-BTL from (+)-BTL was significantly higher than that of (-)-4-OH-BTL from (-)-BTL in the liver microsomal fractions from the two kinds of monkeys. The 4-OH-BTL-forming activity from racemic BTL was significantly lower than from enantiomeric BTL, indicating a possible metabolic interaction between BTL enantiomers. The in vitro profiles observed in the monkeys were very similar to those in humans, but the stereoselectivity in BTL metabolism [(+)-BTL > (-)-BTL] in the primates was found to be reverse to that in rats [S. Narimatsu et al., Anal. Biochem., 222, 256-261 (1994)]. The 4-OH-BTL-forming activity from BTL enantiomers was significantly suppressed by quinidine and quinine, while the former was more potent than the latter, and also by alpha-naphthoflavone. Furthermore, the activity was also suppressed by antisera against rat cytochromes P450-2D2 and -1A2 in concentration-dependent manners. However, kinetics showed that enantiomeric BTL 4-hydroxylation was monophasic in liver microsomes from marmosets of both genders and from male Japanese monkeys. These results suggest that cytochrome P450-2D and -1A enzymes with similar Km values are involved in BTL 4-hydroxylation in monkey liver microsomes.

Purification and characterization of rhesus monkey liver amido hydrolases and their roles in the metabolic polymorphism for E6123, a platelet-activating factor receptor antagonist

We previously showed that a polymorphism for E6123 [(S)-(+)-6- (2-chlorophenyl)-3-cyclopropanecarbonyl-8,11-dimethyl-2,3,4,5- tetrahydro-8H-pyrido[4',3':4,5]thieno[3,2-f][1,2,4]triazolo[4,3-a] [1,4]diazepine] metabolism exists only in rhesus monkeys. In the present study, we purified, from rhesus monkey hepatic microsomes, three amido hydrolases that are involved in the metabolic polymorphism. Two forms of amido hydrolase from an extensive metabolizer and one from a poor metabolizer were purified by Q-Sepharose Fast Flow, Red A-agarose, octylamino-Sepharose 4B, and hydroxyapatite-Ultrogel chromatography, after solubilization with Lubrol. The three purified enzymes had the same molecular mass (47 kDa), and their amino-terminal amino acid sequences were identical. The enzymes were different from various known carboxylesterases in terms of substrate specificity, molecular mass, and amino-terminal amino acid sequence. They resembled arylacetamide deacetylase from human hepatic microsomes with respect to molecular mass and amino-terminal amino acid sequence. The KM values of the high and low affinity enzymes in the extensive metabolizer and the sole enzyme in the poor metabolizer were 37.6, 73.0, and 76.5 microM, respectively. The Vmax values were 3312.4, 504.8, and 427.9 pmol/min/mg of protein, respectively. The high affinity enzyme in extensive metabolizer appears to be quite distinct, whereas the low affinity enzyme in extensive metabolizer in similar or identical to the sole enzyme in poor metabolizer. Thus, the metabolic polymorphism in rhesus monkey may depend upon the existence of the high affinity enzyme in extensive metabolizer.

Elevation of serum soluble tumour necrosis factor (TNF) receptor and IL-1 receptor antagonist levels in bronchial asthma

The specific inhibitor for TNF-alpha activity, soluble form of the 55-kD TNF receptor (sTNF-RI) and soluble form of the 75-kD receptor (sTNF-RII), and the specific inhibitor for IL-1 activity, IL-1 receptor antagonist (IL-1Ra), have been identified. It has been shown that the levels of these inhibitors are elevated in plasma/serum and biological fluids in several diseases, and the protective and inhibitory effect of these inhibitors exist in several inflammatory diseases. In the present study, we measured serum levels of sTNF-RI, STNF-RII and IL-1Ra by ELISA in 36 patients with bronchial asthma (16 atopic and 20 non-atopic) during asthma attacks and in stable conditions in order to assess the state of these inhibitors in allergic inflammation. The levels of sTNF-RI, sTNF-RII and IL-1Ra in sera obtained during bronchial asthma attacks were higher than those in sera obtained in stable conditions. These findings were obtained regardless of atopic status. These results suggest that higher levels of serum sTNF-RI, sTNF-RII and IL-1Ra may reflect up-regulation of TNF-R expression and IL-1Ra production in allergic inflammation, and sTNF-RI, sTNF-RII and IL-1Ra may contribute to regulating TNF-alpha- and IL-1-mediated production and development of allergic inflammation.

Lower serum concentrations of cytokines in elderly patients with pneumonia and the impaired production of cytokines by peripheral blood monocytes in the elderly

It has been well documented that the immune function declines with age; however, little is known about the monocyte/macrophage function of age. In the present study, we measured the concentrations of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-1 beta, tumour necrosis factor-alpha (TNF-alpha), IL-8 and monocyte inflammatory protein-1 alpha (MIP-1 alpha) in sera from 15 elderly patients and 22 young patients with pneumonia, in the acute phase and after recovery, by ELISA. In addition, we measured the concentrations of these cytokines in culture supernatants from lipopolysaccharide (LPS)-stimulated peripheral blood monocytes from normal healthy elderly subjects and young subjects in order to clarify the ability of the elderly to produce these cytokines. The concentrations of these cytokines in sera from old patients and in those from young patients obtained in the acute phase were higher than those in sera obtained after recovery phase. However, the concentrations of these cytokines in the acute phase were lower in elderly patients compared with those in young patients. Serum concentrations of cytokines did not appear to be associated with clinical outcome. In the production of these cytokines by monocytes, LPS-stimulated monocytes from healthy normal elderly subjects produced smaller amounts of G-CSF, GM-CSF, IL-1 beta, TNF-alpha, IL-8 and MIP-1 alpha than those from healthy normal young subjects. These results with the impaired production of these cytokines in the elderly may prove, at least in part, the characteristic features of host defence mechanisms of the elderly.

Localization of a novel non-peptide angiotensin II type 1 receptor antagonist, E4177, in rat adrenal glomerulosa

We investigated the distribution of a novel angiotensin II type 1 (AT1) receptor antagonist, E4177 (4'-[2-cyclopropyl-7-methyl-3H-imidazo[5,4-b]pyridine-3-yl]methyl-2- biphenylcarboxylic acid), in rat adrenal glomerulosa. In a binding assay of adrenal capsular tissue (mainly glomerulosa), E4177 exhibited a maximum displacement of approximately 80% of total 125I-labeled angiotensin II (125I-[Sal1, Ile8] Ang II) binding, and its IC50 value was 6.9 +/- 0.5 nM. This IC50 value indicated a slightly higher in vitro potency than that of losartan (21.0 +/- 0.6 nM). Also, in a receptor autoradiographic study, E4177 (10000 nM) displaced approximately 80% of radiolabeled 125I-[Sal1, Ile8] Ang II in rat adrenal glomerulosa and caused only slight displacement in rat adrenal medulla. Further, light and electron microscopic autoradiography of adrenal glomerulosa for 15 min after the intravenous administration of 1 mg/kg [14C]E4177, indicated the localization of 14C, possibly in the adrenal zona glomerulosa cell plasma membrane. It was strongly suggested that E4177 is a potent and selective antagonist of the AT1 receptor, and that it specifically binds to AT1 receptors in the adrenal zona glomerulosa.

Fatty acids selectively inhibit eukaryotic DNA polymerase activities in vitro

The in vitro relationship between eukaryotic DNA polymerases and fatty acids was investigated. Some fatty acids strongly inhibited the activities of DNA polymerase alpha and/or beta in vitro. The kinetics of inhibition by linoleic acid showed that DNA polymerase alpha was non-competitively inhibited with respect to the DNA template and substrate (dTTP), while DNA polymerase beta was inhibited competitively with both DNA and substrate.

Cytochrome P450 enzymes involved in the enhancement of propranolol N-desisopropylation after repeated administration of propranolol in rats

Repeated oral administration of propranolol (PL, 100 mg/kg daily, for 5, 10 and 15 days) to male Wistar rats increased PL N-desisopropylase and decreased PL 4-,5- and 7-hydroxylase activities in liver microsomes. The increase was highest at the 10 day time point whereas the decrease was relatively constant over the 15 day treatment period. There were no significant changes in the total content of cytochromes P450 (P450) or cytochrome b5 or in NADPH-cytochrome c reductase activity during the PI, treatment. The enhanced N-desisopropylase activities were markedly inhibited by alpha-naphthoflavone (a P450-1A1/2 inhibitor), and moderately by triacetyloleandomycin (a P450-3A1/2 inhibitor) and diethyldithiocarbamate (a P450-2E1 inhibitor). Phenacetin O-deethylase activity, an index of P450-1A2, was significantly increased on day 5, 10 and 15 of the treatment, whereas p-nitrophenol hydroxylase activity was elevated on day 10 only. The PL N-desisopropylation showed a strong and significant correlation with phenacetin O-deethylation, and a weaker but significant correlation with p-nitrophenol hydroxylation. Immunoblot analysis revealed that a protein band corresponding to P450-1A2 was increased by PL pretreatment, and protein band corresponding to P450-3A tended to be increased slightly, but other protein band corresponding to the subfamily of P450-2B, -2C, or -2E was not changed. Pretreatment of rats with P450 inducers (beta-naphthoflavone, phenobarbital, acetone and dexamethasone) increased PL N-dealkylase activity in liver microsomes. Furthermore, antibodies raised against P450-1A and -3A enzymes suppressed PL N-desisopropylation in a concentration-dependent manner, but P450-2E antibody did not. Reconstitution studies showed that P450-1A1, -1A2, -2E1 and -3A2 exhibited catalytic activities for PL N-dealkylation. These results suggest that P450-1A2 is a major PL N-desisopropylase in the PL-treated rats, and P450-3A related enzyme(s) and P450-2E1 as a moderate or minor enzyme are also involved in PL N-dealkylation in native and PL-treated rats.

Patient with both lupus anticoagulant and acute disseminated encephalomyelitis

We present the unusual case of 16-year-old girl who developed intractable convulsions five days after the onset of a cold. Meningeal signs, lymphopenia, proteinuria, and lupus anticoagulant were also present. Treatment with anticonvulsants, antituberculous agents, and adenine arabinoside were ineffective. The initiation of methylprednisolone pulse therapy immediately resolved convulsions and fever. The diagnosis, suggested by the clinical course and the marked improvement of the meningoencephalitis by pulse therapy, was an encephalitic form of acute disseminated encephalomyelitis. Clinical and laboratory findings indicated that an immune disorder may have triggered an abnormal response to a viral infection leading to this patient's neurologic disorder.

Restriction fragment length polymorphism analysis in the HLA class III genes of patients with diffuse panbronchiolitis

Although diffuse panbronchiolitis (DPB) is known to be positively associated with certain major histocompatibility complex (MHC) class I antigens, e.g., HLA-B54 in Japanese patients, it is not clear whether the MHC genes predispose to the disease or are markers for other disease susceptibility gene(s). Because the HLA class III genes such as tumor necrosis factor (TNF) or the fourth component of complement (C4) are localized in the proximity of the HLA-B locus, one or more of these genes might be responsible for susceptibility to DPB. To analyze the role of HLA class III genes in DPB patients, we first evaluated the HLA-B54 association in 32 patients with DPB, and subsequently, studied the restriction fragment length polymorphism (RFLP) of the TNF-alpha and -beta (TNF-alpha/beta) genes as well as the C4A and B (C4A/B) genes in DPB patients and normal individuals. The HLA-B54 antigen was significantly more frequent in DPB patients than in normal individuals (40.3% vs 13.0%, p < 0.001), however, we did not detect a significant association between DPB and gene polymorphisms of either TNF-alpha/beta or C4A/B. Furthermore, there was no evidence of C4A gene deletion in patients with DPB. These results suggest that the HLA-B54 antigen itself might be directly involved in the pathogenesis of DPB.

Regioselectivity and substrate concentration-dependency of involvement of the CYP2D subfamily in oxidative metabolism of amitriptyline and nortriptyline in rat liver microsomes

Kinetic analysis of the metabolism of amitriptyline and nortriptyline using liver microsomes from Wister rats showed that more than one enzyme was involved in each reaction except for monophasic amitriptyline N-demethylation. The Vmax values particularly in the high-affinity sites for E-10-hydroxylation of both drugs were larger than those for Z-10-hydroxylations. Their E- and E-10-hydroxylase activities in Dark-Agouti rats, which are deficient for CYP2D1, were significantly lower than those in Wistar rats at a lower substrate concentration (5 microM). The strain difference was reduced at a higher substrate concentration (500 microM). A similar but a smaller strain difference was also observed in nortriptyline N-demethylase activity, and a pronounced sex difference (male > female) was observed in N-demethylation of both drugs in Wistar and Dark-Agouti rats. The reactions with the strain difference were inhibited concentration-dependently by sparteine, a substrate of the CYP2D subfamily, and an antibody against a CYP2D isoenzyme. The profiles of these decreased metabolic activities corresponded to that of the lower metabolic activities in Dark-Agouti rats. These results indicated that a cytochrome P450 isozyme in the CYP2D subfamily was involved in E- and Z-10-hydroxylations of amitriptyline and nortriptyline in rat liver microsomes as a major isozyme in a low substrate concentration range. It seems likely that the CYP2D enzyme contributes to nortriptyline N-demethylation.

[Relationship between exercise induced ischemia and left ventricular dysfunction; simultaneous assessment of perfusion and function images with 99mTc-tetrofosmin myocardial scintigraphy]

The purpose of this study was to evaluate the relationship between exercise induced ischemia and left ventricular dysfunction, ergometer exercise 99mTc-tetrofosmin myocardial scintigraphy was performed using one day protocol (exercise/rest). Subjects consisted of 68 patients without previous myocardial infarction; without coronary artery disease (CAD) (n = 36) and with CAD (n = 32). Perfusion and function images were evaluated simultaneously. Perfusion image was taken by single photon emission tomography (SPECT). Quantitative analysis was performed with normal data-base. The area of abnormal perfusion, less than normal lower limits, was named as extent score (ES). Left ventricular ejection fraction (LVEF) was measured by first-pass study. According to ES on stress image, 32 patients with CAD were divided into 3 groups; ES < 10% (n = 15), ES = 10-20% (n = 7) and ES > 20% (n = 10). LVEF at rest among 4 groups were not different. LVEF at peak exercise was 61.7+/ -5.3% in CAD (-), 59.0 +/- 5.8% in ES < 10%, 57.4 +/- 6.6% in ES = 10-20% and 47.4 +/- 10.5% in ES > 20%. LVEF in ES > 20% at peak exercise was lowest significantly. Thus, simultaneous perfusion and function images were evaluated for the relationship between exercise induced ischemia and left ventricular dysfunction. If extent score on stress image was more than 20% of left ventricle, significant left ventricular dysfunction was observed.

Retinoic acid regulates differentially the expression of IL-1 beta and IL-1 receptor antagonist (IL-1ra) in PMA-activated human monocytes

Retinoic acid (RA) is a well-known immunological modulator. Although it has been shown that RA stimulates IL-1 expression in monocytes, it is of interest for understanding of the regulatory role of RA in inflammation to examine whether RA also modulates the expression of the IL-1 receptor antagonist (IL-1ra), which is reported to reduce IL-1 beta-mediated inflammation. In this study, we examined the effect of RA on expression of IL-1 beta and IL-ra in phorbol-myristate-acetate (PMA)-activated human monocytes. RA enhanced gene expression and production of IL-1 beta in PMA-activated monocytes. However, interestingly, gene expression and production of IL-1ra in the cells were markedly inhibited by RA. These results show that RA differentially regulates IL-1 beta and IL-ra expression in PMA-activated human monocytes and suggest that RA may promote IL-1-mediated inflammation.

Alterations in glutathione homeostasis in mutant Eisai hyperbilirubinemic rats

Eisai hyperbilirubinemic rats (EHBR) are mutant Sprague-Dawley rats that exhibit impaired biliary organic anion and reduced glutathione (GSH) secretion. In addition, liver GSH levels are twice that of age-matched controls. The mechanisms for the defect in biliary GSH secretion and the increase in cell GSH are not fully understood. We previously showed that canalicular membrane-enriched vesicles isolated from EHBR livers exhibited normal GSH transport. In the present study, we examined the steady-state rat canalicular reduced glutathione transporter (RcGshT) messenger RNA (mRNA) and protein levels, as well as the mechanisms for the increase in cell GSH. Both Northern and Western blot analyses of EHBR livers showed nearly identical RcGshT mRNA and polypeptide levels, respectively, as compared with controls. Treatment with phenobarbital, which increased steady-state RcGshT mRNA by five- to sixfold, RcGshT polypeptide, and biliary GSH secretion by onefold in controls, had a smaller effect on steady-state RcGshT-mRNA level in EHBR (by 1.5-fold) and did not increase RcGshT polypeptide or biliary GSH secretion. In examining possible mechanisms for increased liver GSH, both cysteine level and gamma-glutamylcysteine synthetase (GCS) activity were significantly higher than controls, while the activity of GSH synthetase was unchanged. Northern and Western blot analyses also showed increased steady-state GCS heavy subunit (GCS-HS) mRNA and polypeptide levels, respectively. In addition to liver, GSH levels in kidney, duodenal, jejunal, and ileal mucosa of EHBR were 200% to 300% of age-matched control rats. GCS activity was also increased in kidney cytosol of EHBR. Thus, the defect in biliary GSH secretion in EHBR most likely is either at the posttranslational level of RcGshT or in the inhibition exerted by retained endogenous organic anions. In addition, there is a widespread up-regulation of GSH synthesis capacity in the tissues of EHBR.

cDNA cloning of the hepatocyte canalicular isoform of the multidrug resistance protein, cMrp, reveals a novel conjugate export pump deficient in hyperbilirubinemic mutant rats

ATP-dependent transport of glutathione and glucuronate conjugates from hepatocytes into bile is mediated by a distinct member of the ATP-binding cassette superfamily. We have cloned and sequenced the canalicular isoform of the multidrug resistance protein from rat liver, and termed it cMrp. This membrane glycoprotein is composed of 1541 amino acids with an identity of 47.8% with the human multidrug resistance protein (MRP) and of 41.9% with the yeast cadmium factor (YCF1). The carboxyl-terminal 130 amino acids of the human hepatocyte canalicular isoform of MRP (cMRP) were 80.2% identical with rat cMrp. cMrp was not expressed in the liver of two mutant rat strains, the Eisai hyperbilirubinemic rat and the GY/TR- mutant, which are deficient in the ATP-dependent transport of conjugates across the canalicular membrane. Immunoblotting using an antibody raised against the carboxyl terminus of cMrp detected the glycoprotein of about 190 kDa only in the canalicular membrane from normal liver. Double immunofluorescence and confocal laser scanning microscopy localized cMrp exclusively to the canalicular membrane domain of hepatocytes and demonstrated its loss in the hyperbilirubinemic mutant rat. The results identify cMrp as a canalicular transport protein with a novel sequence and with a function similar to the one of the MRP.

[A case of acquired immunodeficiency syndrome associated with cryptococcemia and cryptococcal meningitis]

A case of acquired immunodeficiency syndrome (AIDS) developed cryptococcosis which was successfully treated with amphotericin B (AMPH) and fluconazole (FLCZ) is reported. A 52-year-old man was admitted because of pyrexia and oral candidiasis. He had a history of multiple sexual exposures to persons at risk for AIDS in Thailand. On admission, serologic tests for human immunodeficiency virus (HIV)-1 were positive on both EIA and Western blot analysis for anti-HIV-1 antibody. Furthermore, test for cryptococcal antigen and fungal cultures from blood and cerebrospinal fluid revealed that he was suffering from cryptococcemia and cryptococcal meningitis. In spite of identification of Cryptococcus neoformans in his blood and cerebrospinal fluid, the finding of cerebrospinal fluid had a minimal inflammatory response with mild elevation of protein. He was initially treated with intravenous AMPH, 10 to 30 mg a day, for 7 weeks, and then was given oral FLCZ, 400 mg a day, for the suppressive therapy. His fever subsided three weeks after the start of AMPH therapy. He was eventually discharged 9 weeks after the start of therapy without any symptoms, and continued to receive oral FLCZ as an out-patient. Thus, attention should be paid to diagnosis and treatment for cryptococcal meningitis in AIDS patients.

[Swyer-James syndrome with bronchial asthma and recurrent spontaneous pneumothorax]

An 18-year-old woman was admitted to our hospital for treatment of the fifth episode of spontaneous pneumothorax. She had a history of repeated pneumonia in childhood and mycoplasma pneumonia at 12 years of age. A chest X-ray film revealed a left-sided pneumothorax, atelectasis of the left upper lobe, and hyperlucency of the left lung. A bronchogram showed poor filling of the peripheral bronchi by contrast medium and mild cylindrical bronchiectasis in the proximal bronchi. Pulmonary arteriography showed small left pulmonary arteries. From these findings, Swyer-James syndrome was diagnosed. This case was complicated by bronchial asthma, with eosinophilia, a high level of IgE, and airway hyperresponsiveness. Atelectasis, multiple bullae, and bronchial asthma had been caused by mycoplasma pneumonia in childhood. Recurrent pneumothorax had been caused by emphysematous changes in the bronchioli and by underdeveloped pulmonary arteries. Surgery to treat the recurrent spontaneous pneumothorax was considered, but was not done because of the risk of relapse and the ventilation-perfusion imbalance due to the Swyer-James syndrome.

Characterization of the oxidation reactions catalyzed by CYP2D enzyme in rat renal microsomes

Monooxygenase activities in rat renal microsomes were determined with the substrates of hepatic CYP2D enzymes. Seven kinds of CYP2D-mediated monooxygenase activities and immunochemically determined CYP2D contents in kidneys corresponded to approximately 3% of those in livers. Debrisoquine 4-hydroxylase and bunitrolol 4-hydroxylase in renal microsomes were inhibited almost completely by the antibody against a CYP2D enzyme purified from rat liver. A marked strain difference (Wistar > Dark Agouti) in these activities was observed in kidney like in liver. The two hydroxylases were inhibited stereoselectively by quinine and quinidine both in renal and hepatic microsomes. Substrate stereoselectivity in (+)- and (-)-bunitrolol 4-hydroxylase activities in kidneys was also consistent with that in livers. These results suggested that the CYP2D enzyme(s) was expressed in the kidney at levels much less than in the liver but had similar functions to those in the liver.

[Hypertonic saline induced bronchoconstriction in sensitized rabbits]

Hypertonic saline is a potent stimulus to airway narrowing in most asthmatic patients. However, the mechanism of airway narrowing induced by a change in osmolarity is not clearly understood. In ovalbumin-sensitized rabbits, we found that bronchoconstriction occurred after inhalation of hypertonic saline, and then studied the mechanisms responsible for this bronchoconstriction. Eighteen anesthetized, paralyzed, mechanically ventilated (40 breath/min, TV 7 ml/kg) ovalbumin-sensitized rabbits were exposed to aerosols of hypertonic saline (ultrasonic nebulizer, 0.5 ml/min, 1 min). Total lung resistance (RL) and dynamic compliance (Cdyr) of the lung were measured before and after the exposure. The concentration of NaCl was increased from 0.9% to 7.2% in 0.9% steps. RL increased and Cdyr decreased as the dose of NaCl rose and they reached plateaus at doses of 6.3% and 7.2%, respectively. These responses were markedly inhibited by treatment with atropine (5 mg/kg i.v., p < 0.05 vs. control group), but treatment with chlorpheniramine (1 mg/kg iv.) suppressed the responses only at low concentrations of NaCl. In contrast, treatment with indomethacin, did not significantly change the responses. We conclude that inhalation of hypertonic saline can cause bronchoconstriction in sensitized rabbits, and that vagal stimulation plays a major role in this bronchoconstriction.

Elevation of plasma-soluble tumour necrosis factor receptors (TNF-R) in sarcoidosis

Two types of receptor for tumour necrosis factor-alpha (TNF-R), the 55-kD receptor (TNF-RI) and the 75-kD receptor (TNF-RII), have been identified. Soluble TNF-RI (sTNF-RI) and soluble TNF-RII (sTNF-RII) can be measured in culture supernatants and biological fluids, and the role of sTNF-R has been suggested. In the present study, we measured plasma sTNF-RI and sTNF-RII levels in 19 patients with active sarcoidosis by ELISA in order to assess the state of both types of receptors in this disease. Both plasma sTNF-RI and sTNF-RII levels in patients with active sarcoidosis were significantly higher than those in normal control subjects. A longitudinal evaluation of plasma sTNF-RI and sTNF-RII levels showed that the magnitude of changes in sTNF-RII was closely related with the clinical course of sarcoidosis. These results suggest that plasma sTNF-RII levels may be useful parameters for monitoring the clinical course of sarcoidosis as well as markers for identifying disease activity.

Abnormal Q wave, ST-segment elevation, T-wave inversion, and widespread focal myocytolysis associated with subarachnoid hemorrhage

A 74-year-old Japanese woman with subarachnoid hemorrhage was admitted to our hospital. During her hospitalization, serial electrocardiograms showed the combination of abnormal Q waves, ST-segment elevation, and T-wave inversion, which strongly suggested acute myocardial infarction. However, postmortem examination revealed widespread focal myocytolysis of the myocardium which was unrelated to vascular distribution.

[Clinical evaluation of fiberoptic bronchoscopy for the diagnosis of solitary pulmonary nodules 2 cm or less in diameter of chest roentgenogram]

The value of fiberoptic bronchoscopy in the diagnosis of solitary pulmonary nodules was studied. The subjects were 59 patients with chest-roentgenographic evidence of a solitary pulmonary nodule 2 cm or less in diameter. Definitive diagnoses were made in 34 patients (57.6%). Primary lung care was diagnosed 21 of 32 patients (65.6%), pulmonary tuberculosis in 7 of 12 (58.3%), metastatic lung cancer in 3 of 5 (60%), old lesions in 3 of 5 (60%), and pulmonary filariasis in 0 of 1 (0%). The diagnostic sensitivity of transbronchial biopsy was superior to that of curettage, and combining the two techniques further improved the diagnostic yield. Bronchial lavage was not effective for diagnosis of lung cancer, but was effective for diagnosis of pulmonary tuberculosis. Diagnostic yield was less for nodules in upper lobes than for those in other lobes, and most malignant tumors that were not diagnosed from the results of fiberoptic bronchoscopy were in upper lobes. We conclude that combining various fiberoptic bronchoscopic procedures can improve the diagnostic yield in patients with small pulmonary nodules. CT-guided needle biopsy and video-assisted thoracoscopic biopsy are two such procedures. Early diagnosis of small pulmonary nodules requires a skilled bronchoscopist who can choose the most appropriate method for biopsy.