[Acute lymphoblastic leukemia with "masked" Philadelphia chromosome].

A 76-year-old woman with leukocytosis and thrombocytopenia was admitted to our hospital. A bone marrow examination showed a composition of 82.0% blasts, i.e., positive for TdT, CD10, CD19, CD34, and HLA-DR and negative for cyCD3, CD13, CD33, MPO, and cyµ. The reverse transcription-polymerase chain reaction analysis revealed a minor BCR-ABL1 fusion gene, leading to a diagnosis of acute lymphocytic leukemia (ALL) with a BCR-ABL1 fusion gene. G-band assay was negative for Philadelphia (Ph) chromosome and also revealed add (21) (q22. 1) and del (20) (q11. 2q13.3). Fluorescence in situ hybridization (FISH) assaying revealed a positive BCR-ABL1 fusion signal. Thus, this patient was diagnosed as Ph chromosome-negative and BCR-ABL1-positive fusion gene ALL, which suggested the presence of ALL with the "masked" Ph chromosome found in approximately 1% of chronic myeloid leukemia. Therefore, the FISH analysis may complement cytogenetic analysis when cytogenetic and molecular genetic findings are contradictory in ALL.

[De novo blast phase of chronic myeloid leukemia with 3q26 abnormality diagnosed by cytogenetic analysis of extramedullary lesion].

A 62-year-old woman was presented at our hospital with visual disturbance. An ocular examination revealed bilateral Roth spots. Laboratory data revealed leukocytosis (236,200 µl) with an excess blast (11%). Physical examination and computed tomography (CT) showed systemic lymphadenopathy. A bone marrow examination revealed a composition of 9.2% blast. Chromosomal analysis on bone marrow cells revealed 46,XX,t (3;12)(q26.2;p13),t (9;22)(q34.1;q11.2) in 80% of metaphases (16/20). Inguinal lymph node biopsy revealed diffuse proliferation of myeloperoxidase (MPO)-positive abnormal cells. Fluorescence in situ hybridization analysis was used to detect the BCR-ABL1 fusion gene and split the signals of MECOM and ETV6. She was diagnosed with de-novo chronic myeloid leukemia (CML) extramedullary blast crisis. She received tyrosine kinase inhibitor (TKI) combination chemotherapy and allogeneic hematopoietic stem cell transplantation and achieved a major molecular response. In this study, we reported a case of CML in blast-phase initially presenting as extramedullary, in which cytogenetic and molecular analyses were useful in the staging method.

Intra-Plaque Vessels on Contrast-Enhanced Ultrasound Sonography Predict Carotid Plaque Histology.

BACKGROUND AND PURPOSE: Although the echogenicity of carotid plaques on carotid enhanced ultrasound (CEUS) was reported to correlate with the historological density of intra-plaque neovessels, it is unclear whether the intra-plaque vessel size is associated with carotid plaque vulnerability. We evaluated the relationship of size of intra-plaque vessels on CEUS with carotid plaque histology. METHODS: We prospectively registered patients with carotid stenosis who were hospitalized to receive carotid endarterectomy between 2012 and 2016. CEUS was performed by ultrasound specialists using a 7-MHz linear transducer (GE LOGIQ7; GE Healthcare, Milwaukee, WN, USA). Sonazoid® was used for conducting CEUS. The sizes of microbubbles inside the plaques were scored at 0, 1, 3, and 5 min after the injection of contrast agent, and were categorized according to our defined vascular score (Vas-S; 0: the effect of contrast was not recognized; 1: the microbubbles were visible, but so blurred and vague that their shape could not be recognized; 2: dot or string-like microbubbles with movement, localized in part or the whole site of the plaque). At histological examination, we simplified the modified American Heart Association classification and defined as an atherosclerotic category (Ath-cat; 1: unruptured plaque; 2: ruptured plaque; 3: healed plaque). We then assessed the correlation of Vas-S with Ath-cat, which describes the process of rupture and restoration of carotid plaques. RESULTS: A total of 97 patients were included in this study. A higher Ath-cat was significantly associated with higher Vas-S at any time. Spearman signed-rank test indicated that Vas-S at 1 min was most strongly correlated with Ath-cat (ρ = 0.43, p = 0.001). Receiver operating curve analysis indicated that a Vas-S of 0 at 1 min was significantly associated with an unruptured plaque (area under curve [AUC] 0.72, p = 0.006), while a Vas-S of 2 at 1 min was significantly associated with a healed plaque (AUC 0.72, p = 0.001). CONCLUSION: Vas-S values of 0 and 2 at 1 min indicated unruptured and healed plaques respectively. Thus, a Vas-S of 1 at 1 min is an indicator of a ruptured plaque. The intra-plaque vessel size on CEUS was significantly associated with carotid plaque histology, and may predict the process of plaque rupture and restoration.

High serum level of methylglyoxal-derived AGE, Nδ-(5-hydro-5-methyl-4-imidazolone-2-yl)-ornithine, independently relates to renal dysfunction.

BACKGROUND: The dicarbonyl methylglyoxal reacts primarily with arginine residues to form advanced glycation end products, including Nδ-(5-hydro-5-methyl-4 -imidazolone-2-yl)-ornithine (MG-H1), which are risk factors for not only diabetic complications but also lifestyle-related disease including renal dysfunction. However, the data on serum level and clinical significance of this substance in chronic kidney disease are limited. METHODS: Serum levels of MG-H1 and Nε-(carboxymethyl) lysine (CML) in 50 patients with renal dysfunction were measured by liquid chromatography/triple-quadruple mass spectrometry. RESULTS: The median serum MG-H1 levels in patients with estimated glomerular filtration rate (eGFR) of ≥30, 15-30, and <15 ml/min/1.73 m2 was 4.16, 12.58, and 14.66 mmol/mol Lys, respectively (p > 0.05). On the other hand, MG-H1 levels in patients with HbA1c of <6 and ≥6 % was 12.85 and 10.45 mmol/mol Lys, respectively, the difference between which is not significant. In logistic regression analysis, decreased renal function (eGFR <15 ml/min/1.73 m2) significantly associated with high serum levels of MG-H1 [odds ratio: 9.39 (95 % confidence interval 1.528-57.76), p = 0.015; Spearman rank correlation: MG-H1 vs. eGFR, r = -0.691, p < 0.01]. In contrast, the serum level of CML did not correlate with eGFR, but correlated with systolic blood pressure [odds ratio 16.17 (95 % confidence interval 1.973-132.5), p = 0.010; Spearman rank correlation coefficient: CML vs. eGFR, r = 0.454, p < 0.01]. CONCLUSION: These results showed that the serum concentration of MG-H1 was strongly related to renal function rather than to DM.

Nε-(carboxymethyl)lysine Concentration in Debris from Carotid Artery Stenting Correlates Independently with Signal Intensity on T1-Weighted Black-Blood Magnetic Resonance Images.

BACKGROUND AND PURPOSE: Because magnetic resonance imaging (MRI) focuses on the morphological characteristics of carotid artery plaques, its diagnostic value with respect to plaque vulnerability is limited. We examined the correlation between Nε-(carboxymethyl)lysine (CML), a main chemical structure of advanced glycation end-products, and the vulnerability of plaques visualized on MRI scans. MATERIALS AND METHODS: We enrolled 43 patients who had undergone carotid artery stenting (CAS) for carotid artery stenosis; all underwent MRI studies, including black-blood MRI and diffusion-weighted imaging (DWI). The signal intensity ratio (SIR) of plaques to adjacent sternocleidomastoid muscle (P/M) on T1- and T2-weighted images (T1WI, T2WI) was calculated. Protein samples were extracted from debris trapped by a filter device. The concentrations of CML and myeloperoxidase (MPO) were measured by solid-phase enzyme-linked immunosorbent assay. RESULTS: The patients were classified into 2 groups based on their SIR-P/M on T1WI and T2WI scans. We observed a higher incidence of post-CAS DWI lesions in patients with a higher than a lower SIR-P/M on T1WI; the CML and MPO concentrations in their CAS debris were also higher. No such differences were seen in patients with a higher or lower SIR-P/M on T2WI scans. The concentration of CML in CAS debris correlated independently with the SIR-P/M on T1WI of the carotid plaques, and was related to the concentration of MPO in CAS debris. CONCLUSIONS: Our findings suggest CML as a candidate molecular imaging probe for the identification of vulnerable plaques.

Antibody-based detection of advanced glycation end-products: promises vs. limitations.

Advanced glycation end-products (AGEs) of the Maillard reaction were originally measured according to their fluorescent and browning properties. A subsequent study with instrumental analyses such as high-performance liquid chromatography and gas chromatography mass spectrometry more clearly demonstrated the involvement of each AGE structure in pathological conditions. Furthermore, immunochemical methods have also been developed to clarify the localization of AGEs in tissues and measurement of AGEs in multiple clinical samples. Although the involvement of AGEs in age-related diseases has progressed due to immunochemical techniques, the relationship between AGE structure and diseases has not been clear because little was known about the epitope structure of each anti-AGE antibody. However, the development of epitope-identified antibodies against AGEs has made it possible to clarify AGE structures involved in diseases. This review discusses not only the usability of anti-AGE antibodies to evaluate AGEs and disease pathology and screen AGE inhibitors, but also describes their usage.

Clinicopathological study on penetrating atherosclerotic ulcers and aortic dissection: distinct pattern of development of initial event.

An intimal tear is responsible for the development of aortic dissection (AD). Plaque rupture is thought to progress to a penetrating atherosclerotic ulcer (PAU). However, the influences of mechanical stress and atherosclerosis on the intimal tear of AD and plaque rupture of PAU have not been fully understood. We enrolled 27 patients with AD [67.6 ± 11.2 years, female/male (F/M) 12/15] and 10 patients with PAU (71.0 ± 8.64 years, F/M 2/8) who underwent aortic reconstructive surgery in our hospital between 2007 and 2011. We analyzed the clinical data and morphological features of these patients and discuss the role of mechanical stress in the initial event. On clinical examination, hypertension was frequently observed in the patients of both the AD (77.8 %) and PAU groups (90.0 %), while hypercholesterolemia was significantly more prevalent in the PAU group (90.0 %) than in the AD (22.2 %) group. Most lesions of AD (96.3 %) were found in the ascending aorta up to the aortic arch, while those of PAU (90.0 %) were found in the descending and abdominal aortas. On pathological examination, the entrance tear was found in 21 (77.8 %) of the 27 patients with AD, and histologically comprised nonatherosclerotic intima and media. In contrast, the entrance tear was considered as plaque ulcer in 8 (80.0 %) of the 10 patients with PAU. The patients with PAU showed a significantly higher prevalence of soft plaque, complicated lesions, and medial fibrosis than those with AD, whereas patients with AD showed no complicated lesions and had a significantly higher prevalence of cystic medial necrosis than those with PAU. The present study suggests that less atherosclerosis and impairment of media could proceed to intimal tear formation in AD and that the disruption of the fibrous cap could cause the plaque ulcer of PAU.

Non-invasive measurement of skin autofluorescence to evaluate diabetic complications.

Although the accumulation of advanced glycation end-products (AGEs) of the Maillard reaction in our body is reported to increase with aging and is enhanced by the pathogenesis of lifestyle-related diseases such as diabetes, routine measurement of AGEs is not applied to regular clinical diagnoses due to the lack of conventional and reliable techniques for AGEs analyses. In the present study, a non-invasive AGEs measuring device was developed and the association between skin AGEs and diabetic complications was evaluated. To clarify the association between the duration of hyperglycemia and accumulation of skin fluorophores, diabetes was induced in mice by streptozotocin. As a result, the fluorophore in the auricle of live mice was increased by the induction of diabetes. Subsequent studies revealed that the fingertip of the middle finger in the non-dominant hand is suitable for the measurement of the fluorescence intensity by the standard deviation value. Furthermore, the fluorescence intensity was increased by the presence of diabetic microvascular complications. This study provides the first evidence that the accumulation of fluorophore in the fingertip increases with an increasing number of microvascular complications, demonstrating that the presence of diabetic microvascular complications may be predicted by measuring the fluorophore concentration in the fingertip.

Carotid Endarterectomy for Pseudo-occlusion of the Cervical Internal Carotid Artery.

OBJECT: This study described clinicopathological characteristics of pseudo-occlusion (PO) of the internal carotid artery (ICA) with regards to the pathological mechanism and the benefit of carotid endarterectomy (CEA). METHODS: We retrospectively reviewed 17 PO patients who underwent CEA. Clinical presentation, angiographic findings, surgical outcomes and plaque components obtained from CEA were investigated. RESULTS: PO plaques had more fibrous and two different pathological features, including total occlusion with recanalization and severe stenosis. Plaques of the total occlusion with recanalization (8 patients) were composed of thrombotic total occlusion and lumen recanalization by large neovascular channels, whereas those with severe stenosis (9 patients) were fibrous or fibroatheromatous plaque with severe stenosis of the original lumen. Of all the patients who underwent a carotid angiogram 2 weeks after surgery, 16 were successfully treated, but one showed complete occlusion of the ICA. At the follow-up period, two patients showed restenosis of the ICA. Three patients with complete occlusion or restenosis had histologically fibrous sclerotic plaques. CONCLUSION: Patients with PO had more fibrous plaques and two different histological features, including total occlusion with recanalization or severe stenosis. The plaque histology may be related to the pathogenesis and the surgical outcome.

Nε-(carboxymethyl)lysine in debris from carotid artery stenting: multiple versus nonmultiple postoperative lesions.

BACKGROUND: No predictor of postoperative ischemic events has been identified in patients undergoing carotid artery stenting (CAS). We aimed to determine whether N(ε)-(carboxymethyl)lysine (CML) in debris trapped by an embolic protection filter device is a predictor of postoperative ischemic events. METHODS: We enrolled 27 patients (73.4 ± 7.2 years; 22 male, 5 female) who underwent CAS for carotid artery stenosis. Diffusion-weighted magnetic resonance imaging was performed before and after the procedure. Protein samples were extracted from the debris. CML and myeloperoxidase were examined by solid phase enzyme-linked immunosorbent assay and Western blot analysis. RESULTS: Seventeen patients had 0 or 1 new lesion (nonmultiple lesions) postoperatively, whereas 10 patients had 2 or more new lesions postoperatively (multiple lesions). The CML concentration of the protein sample was significantly higher in patients with multiple lesions than in those with nonmultiple lesions (6.26 ± 2.77 ng/mg protein and 3.36 ± 1.57 ng/mg protein, respectively; P = .010). Statin therapy for dyslipidemia was associated with a lower incidence of multiple lesions and a lower concentration of CML in the protein sample (P = .004 and P = .02, respectively). Receiver operating characteristic analysis showed that the area under the curve for CML was significantly greater than .5 (.877; 95% confidence interval, .742-1.00). CONCLUSIONS: CML derived from debris may distinguish between patients with postoperative multiple ischemic lesions and those with postoperative nonmultiple lesions who undergo CAS.

Detection of AGEs as markers for carbohydrate metabolism and protein denaturation.

Approximately 100 years have passed since the Maillard reaction was first reported in the field of food chemistry as a condensation reaction between reducing sugars and amino acids. This reaction is thought to progress slowly primarily from glucose with proteins in vivo. An early-stage product, called the "Amadori product", is converted into advanced glycation end products. Those accumulate in the body in accordance with age, with such accumulation being enhanced by lifestyle-related diseases that result in the denaturation of proteins. Recent studies have demonstrated that intermediate carbonyls are generated by several pathways, and rapidly generate many glycation products. However, accurate quantification of glycation products in vivo is difficult due to instability and differences in physicochemical properties. In this connection, little is known about the relationship between the structure of glycation products and pathology. Furthermore, the interaction between proteins modified by glycation and receptors for advanced glycation end products is also known to induce the production of several inflammatory cytokines. Therefore, those inhibitors have been developed over the world to prevent lifestyle-related diseases. In this review, we describe the process of protein denaturation induced by glycation and discuss the possibility of using the process as a marker of age-related diseases.

Pleomorphic adenoma of the submandibular gland in children: a case report and a review of the Japanese literature.

An 8-year-old girl was introduced to our department due to the presence of a left painless submandibular mass. The mass had been initially noticed at 7 years of age. Preoperative imaging showed the mass to have originated from the left submandibular gland. The mass was removed with a part of submandibular gland attached to it. The pathologic findings showed the mass to be pleomorphic adenoma without any malignant components. The postoperative clinical course was uneventful. During the 1-year follow-up period, no recurrence was noticed. In addition to the clinical report of our case, we reviewed the pertinent Japanese literature to clarify the clinical features of this disease in children.

Multisystem Inflammatory Syndrome in Children: A Case Report From Japan.

This study reports a case of multisystem inflammatory syndrome in children (MIS-C). Although MIS-C is currently not widespread in Japan, it is important to consider this syndrome, particularly when the patient is younger than 21 years and presents with fever and shock symptoms associated with COVID-19. According to the latest statistics updated by the Centers for Disease Control and Prevention in early 2021, the total number of MIS-C patients is only 1659 and there have been no reports from Japan. Therefore, information to accurately diagnose MIS-C is needed. This study is the first case report of MIS-C in Japan, and it proposes information to identify this serious syndrome.

[Three cases of optic neuropathy associated with hypertrophic pachymeningitis].

PURPOSE: We report 3 cases of patients with hypertrophic pachymeningitis associated with perinuclear anti-neutrophil cytoplasmic antibody and IgG 4-positive plasma cell infiltration. CASES: The patients' ages ranged from 61 to 76. Two were women and 2 cases involved one eye only. Initial visual acuity of the 4 eyes were counting fingers to 0.3. Decreasing of critical flicker frequency and moderate headache were observed in all cases. Definite diagnosis of hypertrophic pachymeningitis was made by enhanced MRI (magnetic resonance imaging) using Gadolinium. After systemic administration of methylprednisolone, all patients showed improvement in their visual acuity from 0.8 to 2.0 and had no recurrence. CONCLUSIONS: Hypertrophic pachymeningitis is common in elderly patients. It is highly associated with headaches accompanied by symptoms and signs of ischemic optic neuropathy and retrobulbar optic neuritis. Enhanced MRI is helpful in making a definite diagnosis.

IgG4-positive plasma cells in inflammatory abdominal aortic aneurysm: the possibility of an aortic manifestation of IgG4-related sclerosing disease.

Inflammatory abdominal aortic aneurysm (IAA) is associated with autoimmune disease. However, the precise mechanism of IAA remains unclear. There is increasing evidence that IgG4 is involved in the autoimmune mechanism of various idiopathic sclerosing lesions, including sclerosing pancreatitis and retroperitoneal fibrosis. The present study investigated the hypothesis that the IgG4-related autoimmune reaction is involved in the formation of IAA. The study group consisted of 11 cases of IAA (69.2 +/- 8.59y) and 12 age-matched cases of atherosclerotic abdominal aortic aneurysm (AAA, 69.6 +/- 5.94y), which were used in the previous report. A clinicopathologic examination of these lesions was performed, including histology and immunohistochemistry, in relation to the involvement of IgG4-positive plasma cells in the formation of IAA. No difference in the incidence of risk factors for atherosclerosis was observed between the patients with IAA and AAA. Autoimmune diseases were diagnosed in 2 patients with IAA, including rheumatoid arthritis and polyarteritis nodosa. A patient with IAA had pulmonary fibrosis. In contrast, autoimmune diseases were absent in patients with AAA. However, there was no significant difference in the incidence of autoimmune diseases between the patients with IAA and AAA. Lymphocyte and plasma cell infiltration and fibrosis were significantly more intense and extensive in IAA than in AAA. In addition, lymph follicle formation and vasculitis of small veins and arteries were frequently found in the affected lesions of IAA. Immunohistochemically, IAA showed a significant increase in the number of infiltrating IgG4-positive plasma cells and the incidence of a disrupted follicular dendritic cell network in lymph follicles, in comparison with AAA. These findings suggest that IAA may be an aortic lesion reflecting the presence of IgG4-related sclerosing disease, and not a simple inflammatory aneurysm of the aorta.

Immunological detection of N omega-(Carboxymethyl)arginine by a specific antibody.

N omega-(carboxymethyl)arginine (CMA) is an acid-labile advanced glycation end product (AGE) that was discovered in enzymatic hydrolysate of glycated collagen. Subsequently, CMA was also detected in human serum, and its level in patients with diabetes was found to be higher than in people without the disease. However, the histological localization of CMA and its pathophysiological significance remains poorly understood. Here, to address this issue, we developed a monoclonal antibody specific for CMA. This antibody reacted with CMA and CMA-protein adduct, whereas it did not cross-react with its analogues, such as N epsilon-(carboxymethyl)lysine and S-(carboxymethyl)cysteine, indicating that the antibody specifically recognizes CMA. Upon immunohistochemical analysis, a significant CMA immnoreactivity was found in atherosclerotic lesions, whereas no such immunoreactivity was observed in normal regions. This suggests that the accumulation of CMA in tissue proteins may contribute to the pathophysiologies associated with aging and age-related diseases.

Immunochemical and immunohistochemical studies on distribution of elastin fibres in human atherosclerotic lesions using a polyclonal antibody to elastin-derived hexapeptide repeat.

A polyclonal antibody to elastin-derived hexapeptide repeat, H-(Val-Gly-Val-Ala-Pro-Gly)(3)-NH(2), was prepared in order to investigate the differences between elastin fibres in intimal hyperplasia and media in human atheroscleroic lesions. The hexapeptide repeat and alpha-elastin were recognized by this polyclonal antibody in enzyme-linked immunosorbent assay (ELISA), but other elastin-derived peptides such as tetrapeptide repeat, pentapeptide repeat and nonapeptide were not. In the series of hexapeptide repeats, H-(VGVAPG)(n)-NH(2) where n is 1-7, the polyclonal antibody reacted strongly with oligomers (n = 3-7) and weakly with dimer (n = 2), but not with monomer (n = 1). CD measurements suggested that the beta-turn structure is important for recognition by the polyclonal antibody. In an immunohistochemical study, elastin was stained more strongly in intimal hyperplasia than in media, suggesting that newly synthesized elastin in intimal hyperplasia is morphologically distinct from that in media.

Hypochlorous acid generates N epsilon-(carboxymethyl)lysine from Amadori products.

Since the accumulation of N(epsilon)-(carboxymethyl)lysine (CML), a major antigenic advanced glycation end product, is implicated in tissue disorders in hyperglycemia and inflammation, the identification of the pathway of CML formation will provide important information regarding the development of potential therapeutic strategies for these complications. The present study was designed to measure the effect of hypochlorous acid (HOCl) on CML formation from Amadori products. The incubation of glycated human serum albumin (glycated-HSA), a model of Amadori products, with HOCl led to CML formation, and an increasing HOCl concentration and decreasing pH, which mimics the formation of these products in inflammatory lesions. CML formation was also observed when glycated-HSA was incubated with activated neutrophils, and was completely inhibited in the presence of an HOCl scavenger. These data demonstrated that HOCl-mediated CML formation from Amadori products plays a role in CML formation and tissue damage at sites of inflammation.

Possible involvement of myofibroblast in the development of inflammatory aortic aneurysm.

To clarify the role of myofibroblasts in the development of inflammatory aortic aneurysm (IAA), 11 cases of IAA (69.2+/-8.59 years) were investigated immunohistochemically and were morphometrically compared with 12 age-matched cases of atherosclerotic abdominal aneurysm (AAA, 69.6+/-5.94 years). The positivity of mantle sign and CRP was significantly higher in the IAA group than in the AAA group. The wall of IAA (5.41+/-1.47 mm) was significantly thicker than that of AAA (2.68+/-0.71 mm). A significant increase in the expression of alpha-smooth muscle actin was found in adventitial fibroblasts of IAA compared to those of AAA. The cell density and MIB-1 index of adventitial myofibroblasts were significantly higher in IAA than in AAA (cell density: 1.69+/-0.51 vs. 1.09+/-0.4 x 10(3) cells/mm(2); MIB-1 index: 5.25+/-2.97% vs. 1.55+/-0.71%). IAA showed a significantly lower area ratio (MAR) of adventitial microvessels than did AAA (2.92+/-1.49% vs. 7.51+/-2.64%). However, there was no significant difference in microvessel density (MVD) between IAA and AAA (84.62+/-50.5 vs. 65.1+/-32.6 vessels/mm(2)). In some cases of IAA, adventitial myofibroblasts expressed hypoxia-inducible factor 1alpha in their cytoplasm or nuclei while it was not detected in AAA. These findings suggest that the development of IAA may be partly mediated by the proliferation of adventitial myofibroblasts, which might be related to tissue hypoxia.

Effects of inducible nitric oxide synthase inhibitors on asthma depending on administration schedule.

The effectiveness of two inducible nitric oxide synthase (iNOS) inhibitors on allergic airway inflammation was investigated under different administration schedules. Rats sensitized to ovalbumin (OVA) were exposed to OVA for 3 consecutive days. Both iNOS inhibitors showed markedly different effects between two pretreatment schedules: pretreatment before each of three OVA exposures S1 and before the third exposure alone S2. S1 pretreatment resulted in higher pulmonary resistance than triple OVA alone. This potentiation was associated with increased eosinophil infiltration and malondialdehyde levels in the lungs, which were suppressed by superoxide dismutases (SODs) but not by methylprednisolone. However, the S2 administration of both iNOS inhibitors completely suppressed the airway response. Administration by schedule S1 completely suppressed plasma nitrite and nitrate levels, but that by S2 caused only a slight suppression. The triple OVA exposures resulted in the upregulation of iNOS in alveolar macrophages and arginase activity, Mn- and Cu/Zn-SOD expression, and nitrotyrosine and lipid peroxide deposition in the airway. However, inhibitors administered by schedule S1 suppressed this upregulation, but further potentiated nitrotyrosine, which in turn was inhibited by SOD. Although iNOS inhibitors may be beneficial for asthma, repeated administration may be detrimental because of extensive reduction of NO and downregulation of SOD.