Multibacterial sepsis in an alcohol abuser with hepatic cirrhosis

An alcohol abuser with hepatitis C developed multibacterial sepsis. His mean 100% alcohol intake reached 400 ml/day. In January 2001, he suddenly experienced fever (39 degrees C) with no other symptoms. One week later, he was admitted to our hospital and was subsequently diagnosed with sepsis associated with four species of bacteria (Streptococcus constellatus, Fusobacterium mortiferum, Bacteroides thetaiotaomicron, and non-spore-forming anaerobic gram-positive bacillus). A drip infusion of imipenem/cilastatin was administrated, resulting in a successful therapeutic outcome. No underlying disorder was found except for gastric ulcers and hepatic cirrhosis. Damaged gastric mucosa was assumed to be the possible cause and route for the bacterial invasion.

The relationship between oxidative metabolism and lipid peroxidation in rat liver microsomes

7-ethoxycoumarin was not found to induce lipid peroxidation in rat liver microsomes, although it was reported to cause lipid peroxidation in rat cultured hepatocytes. The productions of thiobarbituric acid reactive substances (TBARS) and chemiluminescence (CL) in the presence of some drugs including tolbutamide, naproxen and salicylic acid and their oxidation activities were determined. There was a negative correlation between extent of oxidative stress and oxidation activities. These results suggested that the oxidative metabolism of these drugs did not directly contribute to the microsomal peroxidation reaction. In addition, naproxen-induced microsomal lipid peroxidation was found to occur in rat, but did not in guinea pig.

Effects of non-steroidal anti-inflammatory drugs on the methotrexate transport in rat small intestine

BACKGROUND

Methotrexate (MTX) is used in the treatment of rheumatic disease, sometimes along with non-steroidal anti-inflammatory drugs (NSAIDs), and is actively co-transported with H+ in the small intestine, mediated by a reduced folate carrier (RFC). The co-administration of NSAIDs with MTX might cause a decrease in MTX absorption through the small intestine, since some NSAIDs are uncouplers of oxidative phosphorylation. The present study investigates whether flufenamic acid, diclofenac and indomethacin, NSAIDs, decrease the ATP content of small intestinal epithelial cells and affect MTX transport (the secondary active transport) in the small intestine.

METHODS

MTX transport was examined in the presence and absence of the NSAIDs, using the everted intestine technique and brush border membrane vesicles (BBMVs) from the rat small intestine. The change in physical properties of the membrane was studied in BBMVs using the fluorescence techniques.

RESULTS

MTX absorption in the small intestine with H+ gradient (mucosal side, pH 6.0; serosal side, pH 7.4) decreased in the presence of the NSAIDs, but absorption without H+ gradient (both sides, pH 7.4) was unaffected. The intestinal mucosal ATP content decreased in the presence of the NSAIDs. The uptake of MTX in BBMVs was unaffected by the NSAIDs. The activity of intestinal Na+-K+-ATPase was enhanced in the presence of the NSAIDs. The fluorescence measurements showed that membrane fluidity, membrane potential and membrane hydrophobicity of BBMVs were unaffected by the NSAIDs.

CONCLUSIONS

NSAIDs decreased the H+/MTX absorption in the small intestine, but not the passive transport. The uncoupling effect of the NSAIDs decreased the ATP content in the small intestine, resulting in inhibition of the secondary active transport.

Cyclosporin-A ameliorated interstitial pneumonitis in a patient with amyopathic dermatomyositis

Abstract A 40-year-old woman with amyopathic dermatomyositis (ADM) developed acute pneumonitis. Despite pulse methylprednisolone therapy, the pneumonitis worsened. We therefore initiated cyclosporin-A (Cy-A) therapy with success, although Pneumocystis carinii (PC) pneumonia occurred. Coexistence of dermatomyositis (DM)-related pneumonitis and PC pneumonia was diagnosed by means of chest X-ray findings, KL-6, and polymerase chain reaction (PCR) for PC. We thus continued Cy-A therapy to ameliorate the pneumonitis. Cy-A appeared to be effective for corticosteroid-resistant pneumonitis in a patient with DM.

[Anti-neutrophil cytoplasmic autoantibody-associated rapid progressive glomerulonephritis complicated with both limited and diffuse scleroderma]

We report two patients with scleroderma, 73-year-old female and 67-year-old female, who developed anti neutrophil cytoplasmic autoantibody (ANCA) associated rapid progressive glomerulonephritis (RPGN). Both patients have had a long history of scleroderma (23 and 14 years, respectively) when ANCA-associated glomerulonephritis occurred. In the first patient, scleroderma was localized in both fingers. She has been followed-up as CREST syndrome rather than systemic sclerosis. The complaints on admission were leg edema and left chest pain in the first patient, and a pyrexia and dyspnea in the second patient. Both patients showed pulmonary manifestation (pleural effusion in the first patient, interstitial pneumonia and alveolar hemorrhage in the second patient, respectively) and rapid progressive glomerulonephritis. Both patients died in spite of corticosteroid therapy. Autopsy findings in the second patient demonstrated crescentic glomerulonephritis and alveolar hemorrhage. Our cases demonstrated that MPO-ANCA associated glomerulonephritis could be associated with limited scleroderma as well as systemic scleroderma. In these condition, the prognosis will be poor if scleroderma seemed to be stable.

[Airway hyperreactivity in patients undergoing hematopoietic stem cell transplantation]

Airway hyperreactivity (AHR) was studied with an astograph for 34 sequential hematopoietic stem cell transplantation (HSCT) patients before and after HSCT. The percentage of Dmin positive patients was 25.0% before HSCT and 25.0-57.1% after HSCT, while all normal subjects were negative for Dmin. The mean Dmin of post HSCT patients was 22.7 u in days 501-1000 and 19.3 u after 1001 days, which was significantly lower than the 45.2 u of normal controls. The patients were divided into two groups according to the treatment before HSCT, strongly treated (S, acute leukemia and non-Hodgikin lymphoma) and weakly treated (W, chronic myelogenous leukemia and aplastic anemia) patients. The ratio of Dmin positive patients and mean Dmin in the W group after HSCT (38.9%, 27.8 u), and the S group before and after HSCT (55.6%, 20.5 u and 45.5%, 23.8 u, respectively), were significantly impaired compared with the findings in the normal controls (0%, 45.2 u). The mean sGrs/Grs count was higher in the W group before HSCT than in the other groups (W before and after HSCT, 0.58 and 0.19, respectively; S before and after HSCT, 0.21 and 0.22, respectively). Taken together, AHR was observed in HSCT patients, particularly for patients in the S group. These data indicate that high dose chemo-radiotherapy including conditioning regimen causes AHR. The mechanisms leading to AHR may be infection, inflammation, and remodeling of the airway.

Subclinical renal tubular acidosis in patients with primary and secondary Sjögren's syndrome: a possible marker of disease progression

Abstract To clarify the prevalence of subclinical renal tubular acidosis (RTA) and its association with clinical and laboratory parameters in primary and secondary Sjögren's syndrome (SS), an acid-loading test was conducted. Subclinical RTA was found in 32% of patients with SS. The prevalence of subclinical RTA in primary and secondary SS was about the same (31.6% and 33.3%, respectively). Significant longer duration of illness, more severely decreased salivary excretion, decreased lymphocyte number, higher serum levels of IgG and IgA, and higher frequency of anti-SS-A (Ro) and SS-B (La) antibodies were found in patients with subclinical RTA. These results suggested that subclinical RTA may be a characteristic manifestation both in primary and secondary SS, along with the progression of immunologic dysfunction, when the illness seemed to be indolent.

[Successful treatment with fludarabine of chronic lymphocytic leukemia associated with nephrotic syndrome]

We successfully treated a patient with chronic lymphocytic leukemia (CLL) associated with a nephrotic syndrome. An 82-year-old man had been diagnosed as having CLL and been under observation for a year without treatment. In January, 2001, he developed hypoprotenemia, proteinurea, and edema in the extremities and face. With the exacerbation of the symptoms, he was admitted to our hospital in March of the same year. Under the diagnosis of nephrotic syndrome with CLL, the patient underwent induction therapy for CLL with fludarabine (13 mg/m2/day for 4 days), which brought about a complete remission of CLL and the disappearance of the edema. To our knowledge, this was the first case in Japan where fludarabine was dramatically effective in treating both CLL and the nephrotic syndrome. This result indicated that fludarabine is beneficial for not only CLL but also complications like nephrotic syndrome.

[Clinical usefulness of a cardiopulmonary sleep study in patients with sleep apnea syndrome]

Although polysomnography is indispensable in the diagnosis of sleep apnea syndrome (SAS), a common disease in Japan, it is a time-consuming procedure. We therefore assessed the clinical usefulness of a cardiopulmonary sleep study (CPSS), which monitors indices of respiratory and circulatory kinetics during sleep. Of ninety male patients (50 +/- 11 years old, BMI: 27 +/- 4), those with apnea indices (AI) > 5, as determined using an apnomonitor, underwent CPSS with a Night Watch System. Sixty-nine patients with indications for nasal CPAP (NCPAP) therapy underwent overnight CPSS and the optimum pressure was determined. AI was 31 +/- 17, whereas CPSS showed an apnea-hypopnea index of 49 +/- 24, a mean SaO2 of 93 +/- 3%, and a minimum SaO2 of 71 +/- 11%, indicating severe OSAS. The mean optimum pressure was 10 +/- 2 cm H2O, and the compliance was 86%, which was comparatively good. As CPSS can be performed on many patients in a short time, it may be useful for the early diagnosis and initial treatment of SAS.

Dose-intensified CHOP (double-CHOP) followed by consolidation with high-dose chemotherapy for high and high-intermediate risk aggressive non-Hodgkin's lymphomas

Patients with aggressive non-Hodgkin's lymphoma (NHL) showing several risk factors have a poor prognosis. In such patients, conventional chemotherapy results in a low complete response rate and a high relapse rate. We performed a prospective trial of intensive induction chemotherapy followed by high-dose consolidation therapy to determine the feasibility of such an approach. We treated 39 patients with aggressive poor risk NHL with double-CHOP (D-CHOP) chemotherapy followed by high-dose therapy (HDT) with or without peripheral blood stem cell transfusion (PBSCT). The median age of the patients was 54 years (range 17-65). Twenty-seven were considered to be at high (H) and 12 were at high-intermediate (H-I) risk according to the age-adjusted International Prognostic Index. Thirty-four patients (87%) responded (complete response: 74%, partial response: 13%) to D-CHOP chemotherapy. Of the 34 responders, 24 received HDT followed by PBSCT, 7 received high-dose methotrexate, and 3 refused consolidation therapy. At a median follow-up period of 26 months, the estimated 3-year overall survival rate and event-free survival rate was 64 and 51%, respectively. Our data suggest that dose-intensified D-CHOP followed by consolidation HDT is safe and appears efficacious in aggressive NHL patients with H-I and H risk.

[CD25 positive chronic eosinophilic leukemia with myelofibrosis]

A 70-year-old man was referred to our hospital in March 2001 for the purpose of evaluation for anemia and thrombocytopenia. Physical examination revealed hepatosplenomegaly, normal skin, and normal neurologic findings. Blood examination showed a white blood cell count of 10,900/microliter, with a differential count of 58.5% eosinophils and 3.5% blast cells. Flow cytometric analysis of eosinophils revealed that they were positive for CD33, CD13, CD25, and HLA-DR. Bone marrow aspiration could not be performed due to dry tap, and bone marrow core biopsy specimen revealed severe myelofibrosis with blastoid cells proliferation. Cytogenetic analysis of bone marrow cells showed isochromosome 17. FISH analysis using a RAR alpha probe (17q21.1) demonstrated 62% of peripheral blood nucleated cells having three signals. BCR/ABL gene rearrangement by FISH analysis was not observed. Allergic disease, infectious disease, parasitic disease, collagen vascular diseases, pulmonary disease, and neoplastic disorders were excluded. Therefore, a diagnosis of chronic eosinophilic leukemia was made. The patient had no symptoms of hypereosinophilia. However, eosinophils with sparse granulation, positivity for CD25, elevated serum levels of soluble IL-2 receptor, and elevated serum levels of eosinophil cationic protein suggested activation of eosinophils. Further analysis is needed regarding the activation of eosinophils in chronic eosinophilic leukemia.

Different clones of t(1;12)/t(12;12) involving the ETV6 gene in a case of acute myeloid leukemia

We describe here a case of a 77-year-old Japanese man who developed acute myeloid leukemia (AML-M2). Chromosome analysis of the bone marrow blast cells showed 46,XY,del(7q) at onset, and after relapse, two clones, 46,XY,t(1;12) and 46,XY,del(7q),t(12;12), were present. Fluorescence in situ hybridization analysis confirmed that each clone with the 12p abnormality involved the ETV6 gene. These findings suggest that the ETV6 gene rearrangements in this case were apparently independent of contribution to leukemogenesis, because this cytogenetic aberration appeared as a secondary change. To our knowledge, this is the first report of two different clones with ETV6 gene rearrangements in the same patient.

Relationship between quality of life and mood or depression in patients with severe obstructive sleep apnea syndrome

STUDY OBJECTIVES

To assess the quality of life (QOL) in patients with severe obstructive sleep apnea (OSAS), and the relationship between the QOL and severity of OSAS, excessive daytime sleepiness (EDS), and mood.

METHODS

Sixty patients with OSAS and 34 normal control subjects were assessed for QOL using the Medical Outcomes Study Short-Form 36 Health Survey questionnaire (SF-36), for EDS using the Epworth sleepiness scale (ESS), and for mood using the Zung self-rated depression scale (SDS). The associations between each domain and the total score on the SF-36 and the baseline characteristics, polysomnographic parameters, ESS score, and SDS score were examined by simple regression analysis and stepwise multiple regression analysis.

RESULTS

Six of eight domains and the total score on the SF-36 were significantly lower than those in the control subjects. The ESS and SDS scores were also more impaired in the patients than in the control subjects. There was no relationship between each domain on the SF-36 and the severity of OSAS and ESS score. Five of eight domains and the total score on the SF-36 were significantly correlated with the SDS score. Stepwise multiple regression analysis selected three variables, the SDS score (partial R(2) = 0.505), the lowest arterial oxygen saturation during sleep (partial R(2) = 0.064), and ESS score (partial R(2) = 0.053), as independent factors for predicting the total score on the SF-36. These three variables accounted for 62.2% of the total variance in the total score on SF-36 (R(2) = 0.622, p < 0.0001)

CONCLUSIONS

The QOL of patients with severe OSAS was decreased compared with normal control subjects. The QOL of patients was strongly correlated with the depression scale on simple regression analysis. However, EDS score and oxygen desaturation during sleep also affected the QOL, although the magnitude of its effect was small.

[Heerfordt syndrome]

The Heerfordt syndrome is characterized by fever, uveitis, swelling of parotid gland and facial nerve palsy, and 53 cases have been reported in Japan until 2000. In the present review, we mainly focused on those clinical cases reported. Most patients were between 20 and 40 years of age, and females appeared to have greater risk than males. The definite diagnosis of this syndrome is established histologically according to sarcoidosis. In addition 67 gallium scan is helpful for diagnosis, and it shows increased uptake of Ga to the ophthal lesion, parotid glands and hilar lesions. Therapeutic trial with prednisolone is sometimes required especially for facial palsy.

p38 mitogen-activated protein kinase and c-Jun-NH2-terminal kinase regulate interleukin-8 and RANTES production in hyperosmolarity stimulated human bronchial epithelial cells

OBJECTIVE

We have previously shown that p38 mitogen-activated protein kinase (MAPK) regulates, at least in part, hyperosmolarity induced interleukin (IL)-8 expression in human bronchial epithelial cells (BEC). In the previous study, hyperosmolarity also activated c-Jun-NH2-terminal kinase (JNK); however, the role of the JNK signalling pathway has not been determined. In the present study, we examined the role of the JNK signalling pathway in hyperosmolarity induced IL-8 and RANTES production by BEC using the novel inhibitor of the JNK signalling pathway CEP 11004 in order to clarify these issues.

METHODS

Bronchial epithelial cells that had been pre-incubated with SB 203580, CEP 11004 or a combination of these were exposed to a hyperosmolar medium and then the p38 MAPK and JNK phosphorylation activity in these cells and IL-8 and RANTES concentrations in the culture supernatants were determined.

RESULTS

The results showed that: (i) hyperosmolarity induced the threonine and tyrosine phosphorylation of p38 MAPK and JNK; (ii) SB 203580, as the specific inhibitor of p38 MAPK activity, and CEP 11004 attenuated hyperosmolarity induced p38 MAPK and JNK activity, respectively; (iii) SB 203580 and CEP 11004, but not PD 98059, partially attenuated IL-8 and RANTES production; and (iv) a combination of SB 203580 and CEP 11004 attenuated IL-8 and RANTES production in an additive fashion.

CONCLUSION

These results indicate that p38 MAPK and the JNK pathway regulate hyperosmolarity induced IL-8 and RANTES production by BEC.

[Risk factors in development of sleep apnea syndrome--a large population study using a simple monitoring system]

We studied the risk factors in the development of sleep apnea syndrome (SAS) in 779 patients (705 males and 74 females) using Apnomonitor R. The apnea index (AI) significantly correlated with the body mass index (BMI), and was higher in obese patients (BMI > or = 25 kg/m2) than in non-obese patients. The prevalence of SAS increased with patient age. Obesity was less common in older than in younger patients. The AI was significantly higher in smokers than in non-smokers, as was the prevalence of SAS. The AI and the prevalence of SAS were higher in smokers than in non-smokers in both obese and non-obese patients. The AI was significantly higher in males than in females, and so was the prevalence of SAS. The AI and the prevalence of SAS were always higher in male obese patients, non-obese patients, smokers, and non-smokers than in female patients in the same categories. These results suggest that obesity, age, smoking, and gender were independent risk factors in the development of SAS.

Patients with systemic lupus erythematosus show a normal responsive search score in exploratory eye movement analysis: comparison with schizophrenia

OBJECTIVE

To assess whether a difference in psychiatric vulnerability exists between patients with systemic lupus erythematosus (SLE) and those with schizophrenia.

METHODS

Twenty women with SLE underwent exploratory eye movement analysis, and a responsive search score (RSS) was obtained, two months after the onset of the disease. Fifteen women with schizophrenia in remission also underwent this analysis. Exploratory eye movement was recorded by an eye mark recorder, which detects corneal reflection of infrared light. The number of eye fixations (instance of more than 0.2 seconds of eye fixation time) was recorded, and the RSS was calculated from eye fixation analysis.

RESULTS

Mean (SD) RSS differed significantly between patients with SLE and those with schizophrenia (9.85 (1.87) v 7.27 (1.58) points, respectively, p<0.0001), whereas no difference in mean RSS was found between patients with SLE and 19 normal women. No difference in mean RSS was found between patients with active SLE and those with inactive SLE (9.51 (1.87) v 10.0 (1.77) points).

CONCLUSION

The psychiatric vulnerability in patients with SLE, measured by the RSS, differs from that in patients with schizophrenia.

C-propeptide region of human pro alpha 1 type 1 collagen interacts with thioredoxin

Thioredoxin (TRX) is one of major components of thiol reducing systems. To investigate the molecular mechanism of TRX function in the lung tissue, we screened a human lung epithelial cell cDNA library for TRX-binding protein by yeast two-hybrid systems. We isolated a plasmid containing C-propeptide region of human pro alpha 1 type 1 collagen (CP-pro alpha 1(1)). CP-pro alpha 1(1) stably binds to wild type TRX but not to mutant TRX, in which redox-active cysteine residues are substituted. Failure of the interaction of mutant TRX with CP-pro alpha 1(1) was confirmed in yeast two-hybrid systems. The CP-pro alpha 1(1)/TRX interaction was increased by dithiothreitol treatment, but was markedly inhibited by hydrogen peroxide or diamide treatment. These data showed that the reducing status of TRX active site cysteine residues is important for the TRX-CP-pro alpha 1(1) interaction, indicating that collagen biosynthesis is under the regulation of TRX-dependent redox control.

Spontaneous clinical and cytogenetic remission of aplastic anemia in a patient with del(13q)

We describe the case of a 64-year-old Japanese man with pancytopenia. Bone marrow biopsy findings were consistent with aplastic anemia. The patient was treated by transfusions without immunosuppressive therapy. Chromosome analysis of bone marrow cells at 6 months after onset showed a 46,XY,del(13) (q14q22) karyotype. The pancytopenia resolved gradually over the next 5 years; chromosome analysis of bone marrow cells at that time yielded normal findings. To our knowledge, this is the first report of spontaneous hematologic and cytogenetic remission of aplastic anemia. These findings suggest that the abnormal clone with deletion of the long arm of chromosome 13 was not sufficient for clonal evolution in aplastic anemia in this case.

Long-term administration of beraprost, an oral prostacyclin analogue, improves pulmonary diffusion capacity in patients with systemic sclerosis

The objective of this study was to assess the effect of beraprost sodium, an oral prostacyclin analogue, on pulmonary function in patients with systemic sclerosis. Seventeen patients, with systemic sclerosis and predicted percent values of carbon monoxide diffusion capacity (%DLCO) of less than 95, received beraprost sodium for at least 12 months. Conventional testing for pulmonary function was performed at 12-month intervals and changes were evaluated with special reference to DLCO. Twelve patients completed the treatment. Nine patients showed improvement in DLCO (12.1 +/- 2.3 to 15.5 +/- 4.4 ml/min/mmHg, P < 0.006) and 10 patients showed an increase in %DLCO (66.6 +/- 11.9 to 87.7 +/- 23.2%, P < 0.004). Total lung capacity, vital capacity and forced expiratory volume remained unchanged. This study showed that DLCO levels in patients with systemic sclerosis improved after the administration of beraprost sodium, probably due to the decrease in pulmonary vascular resistance accompanied by increased cardiac output.

[Human herpesvirus-8 negative primary effusion lymphoma with complete clinical remission after removal of ascites]

A 58-year-old HIV-negative woman was admitted to our hospital with abdominal distension. She had a 5-year history of hypothyroidism and a 4-year history of diabetes mellitus. Physical examination revealed ascites. There was no lymphadenopathy or splenomegaly. Laboratory examination showed elevated levels of serum LDH and Al-p, polyclonal hypergammaglobulinemia, and was positive for anti-nuclear antibody, several autoantibodies and HCV-RNA. A computed tomographic scan of the abdomen and chest showed massive ascites, but there was no evidence of tumor masses or lymph node enlargement. Cytologic examination of the ascitic fluid revealed numerous abnormal lymphocytes which by flow cytometry demonstrated expression of CD5, CD19, CD20, and CD4. Cytogenetical analysis demonstrated a hyperdiploid karyotype, with numerical abnormalities. Southern blot analysis demonstrated rearranged monoclonal bands in JH and c-mycgenes. Polymerase chain reaction (PCR) analysis failed to detect the genomes of EBV and HHV-8 in the abnormal lymphocytes. A diagnosis of primary effusion lymphoma of B cell lineage was made. Following abdominal paracentesis, the patient remained in complete clinical remission for 7 months and died of an unrelated cause (cerebral bleeding). The present case demonstrated an HIV-, HHV-8-, and EBV-negative, and HCV-positive primary effusion lymphoma of B cell lineage, with a unique clinical course.

Purging in autologous hematopoietic stem cell transplantation using adenosine triphosphate (ATP) and 4-hydroperoxycyclophosphamide (4-HC)

In this study, we show potent in vitro purging induced by adenosine triphosphate (ATP) for leukemic cells. The treatment of murine L1210 leukemic cells with 2mM of ATP in vitro for 3h was able to reduce the number of leukemic clonogenic cells by about one order of magnitude presumably by changing the permeability of the leukemic cell membrane. Furthermore, the incubation of L1210 cells with ATP (2mM) and low dose 4-hydroperoxycyclophosphamide (4-HC, 2 microg/ml) for 3h resulted in at least a four-log reduction of clonogenic L1210 cells. Only a slight degree of toxicity to pluripotent hematopoietic stem cells (CFU-S) was observed in both treatment protocols. To determine the efficacy of pharmacological purging by ATP, we designed a murine system to mimic the conditions expected in the clinical setting of autologous transplantation using simulated partial remission marrow (SPRM) which was prepared by mixing normal marrow cells and L1210 cells at a ratio of 9:1. After the SPRM cells were incubated in vitro at a concentration of 1 x 10(6)/ml with both ATP (2mM) and low dose 4-HC (2 microg/ml) for 3h, 5 x 10(4) of the cells were then injected into lethally irradiated 9 weeks male BDF1 mice. All the mice given untreated-SPRM died of leukemia by day 27, whereas none of the recipients transplanted treated-grafts had died by day 70, thus suggesting that the combination use of ATP and 4-HC may be a potentially effective way to purge leukemic cells in autologous stem cell transplantation. The mechanism of the selective killing of leukemic cells is assumed that 4-HC is effectively incorporated into leukemic cells by increasing the permeability of the cell membrane by ATP. Taken together, this simple and rapid procedure is able to purge leukemic cells from autologous bone marrow grafts.

[Thymoma complicated with miliary tuberculosis]

We report a case of thymoma complicated with miliary tuberculosis. A 69-year-old woman was admitted to a hospital because of body weight loss, general fatigue, and dyspnea. Chest X-ray showed a small, diffuse granular shadows in both lungs. Biopsied-specimens from bone marrow and left pharynx revealed granuloma with both giant cells and caseous necrosis. The diagnosis of miliary tuberculosis was made. The patient was then transferred to our hospital. Both chest X-ray and computed tomography conducted on admission revealed a mass in the mediastinum as well as diffuse granular shadows in both lungs. We suspected a presence of thymoma. Anti-tuberculosis therapy was started, and extended thymectomy was performed. The diagnosis of thymoma was confirmed pathologically. Immunological analysis of peripheral blood lymphocytes was done before and after the operation. Negative conversion of PPD reaction was observed after thymectomy. Although the response of peripheral lymphocytes to phytohaemoagglutinin (PHA) and concanavalin A recovered after thymectomy, a marked decrease of the number of CD 4 T cells, a decrease of T helper 1 cells, a slight increase in the number of B cells and cells expressing natural killer cell-related surface markers were observed throughout the course of illness.

Toxicity of ethacrynic acid in isolated rat hepatocytes

Ethacrynic acid, a loop diuretic drug, caused lipid peroxidation in isolated rat hepatocytes. The thiobarbituric acid reactive substances (TBARS) formation showed a good correlation with the leakage of glutamic-oxaloacetic acid transaminase (GOT) from the hepatocytes. The addition of antioxidants such as N, N'-diphenyl-p-phenylenediamine (DPPD) and promethazine to the isolated rat hepatocyte suspension containing ethacrynic acid prevented the lipid peroxidation and decreased the GOT leakage to some extent. SKF-525A inhibited the oxidative metabolism of ethacrynic acid and decreased the TBARS formation, suggesting that the lipid peroxidation was caused by the oxidative metabolism. The intracellular reduced glutathione markedly decreased in the hepatocyte suspension containing ethacrynic acid and the hepatocellular protein sulfhydryls were decreased, which was negatively correlated with the GOT leakage. Thus the ethacrynic acid-induced hepatotoxicity was found to be related to the lipid peroxidation and the decrease of cellular protein sulfhydryls.

[A case report of intralobar pulmonary sequestration with an anomalous artery originating from the celiac artery]

A 43-year-old female was admitted to our hospital because of an abnormality detected in chest radiography. Chest radiographs showed a nodular shadow behind the heart. Chest CT revealed a nodule connected to the descending aorta with increased blood flow in left lower lobe, suggesting the presence of a pulmonary sequestration. Bronchography showed an intralobar sequestrated lung in the left lower lobe. Aortography demonstrated that the sequestrated lung was fed by an anomalous artery 20 mm in diameter, originating from the celiac artery. From those findings, Pryce type IIintralobar pulmonary sequestration was diagnosed, and the left lower lobe was removed. Histological findings from the excised tissues showed mild dilatation of the bronchioles and hypervascularity.

Isotypes of rheumatoid factors in rheumatoid arthritis and chronic liver diseases

Abstract We studied isotype-specific rheumatoid factors (RFs) to clarify their significance in rheumatoid arthritis (RA) and to verify the difference in RF isotypes between RA and chronic liver diseases (CLD). Isotype-specific RFs in RA and in CLD were measured by enzyme-linked immunosorbent assay (ELISA). Most sera (n = 51, 94.1%) from RA patients contained some kind of RF isotypes (92.1% for IgM RF, 76.4% for IgG RF, and 43.1% for IgA RF), and seronegative RA by ELISA was seen in only 11.8% (n = 6). The most characteristic combination of RF isotypes in active RA was IgG, IgA, and IgM. This combination of RF isotypes changed to IgG plus IgM, according to the diminution of RA activity; then, we found only IgM RF in inactive RA. The titers of each RF isotype also decreased in parallel with the activity of RA. IgA RF seemed to be the most sensitive factor for evaluating the activity of RA. In CLD, almost the same high frequency (n = 49, 89.8% for IgM RF, 59.2% for IgG RF), with the same titer levels seen in RA, was observed. On the other hand, IgA RF was significantly lower in frequency (n = 9, 18.4%) and in titer, compared with the finding in RA. Surprisingly, even in CLD, true seronegativity by ELISA was also found in very few patients (n = 4, 8.1%). In CLD, positive RFs detected by agglutination assay were seen more often in chronic hepatitis than in liver cirrhosis. In RA patients, significant associations of IgA RF and the serum concentration of IgA, and IgG RF and the serum concentration of IgG, were observed. On the other hand, in CLD patients, significant associations of IgG RF and the serum IgG concentration, and of IgM RF and the serum IgM concentration, were observed. These results indicated that IgA RF in active RA is the most characteristic RF isotype distinguishing it from other nonrheumatic diseases, as well as from inactive RA. RF isotypes reflected the background polyclonal B-cell activation in different manners in both diseases. In CLD, RF isotypes seemed to be disease-related immunological disorders reflecting disease progression.

Determinants of chronic hypercapnia in Japanese men with obstructive sleep apnea syndrome

STUDY OBJECTIVE

To identify the determinants of chronic hypercapnia (ie, PaCO(2), > or = 45 mm Hg) in men with obstructive sleep apnea syndrome (OSAS) without airflow obstruction.

DESIGN

An analysis was conducted of 143 male patients with OSAS, which had been diagnosed by polysomnography (PSG), who had been referred to a university hospital. Patients were classified as hypercapnic (ie, PaCO(2), > or = 45 mm Hg) and normocapnic (ie, PaCO(2), < 45 mm Hg), and obese (ie, body mass index [BMI], > or = 30 kg/m(2)) or nonobese (ie, BMI, < 30 kg/m(2)). Patients with airflow obstruction (ie, FEV(1)/FVC ratio, < 70%) were excluded from the study. Baseline clinical characteristics, pulmonary function, PSG data, and blood gas data were compared between hypercapnic and normocapnic patients. Correlations between PaCO(2) and several anthropometric, respiratory, and polysomnographic variables were determined by stepwise multiple regression analysis.

RESULTS

Fifty-five patients (38%) were hypercapnic. Hypercapnic patients were younger and heavier, and had more abnormalities on pulmonary and PSG testing. Stepwise multiple regression analysis revealed that the PaCO(2) level was influenced significantly by the mean level of arterial oxygen saturation (SaO(2)) during sleep and by the percent of vital capacity (%VC) (R(2) = 0.430; p < 0.0001), indicating that 43% of the total variance in the PaCO(2) could be explained by the mean SaO(2) and %VC in hypercapnic patients. In contrast, only 13% of the total variance in the PaCO(2) was accounted for by the mean SaO(2) and BMI in normocapnic patients (R(2) = 0.134; p = 0.0034). The mean SaO(2), %VC, and PaO(2) were selected as independent variables for predicting the PaCO(2) in obese patients. These variables explained 41% of the total variance in the PaCO(2) (R(2) = 0.407; p < 0.0001), whereas the mean SaO(2) only accounted for 13% of the total variance in PaCO(2) levels in nonobese patients (R(2) = 0.134; p = 0.0064).

CONCLUSION

Nocturnal desaturation and restrictive pulmonary impairment play major roles in determining the PaCO(2) in hypercapnic and obese OSAS patients without airflow obstruction.

Cooperative functions of the mannoprotein-encoding genes in the biogenesis and maintenance of the cell wall in Saccharomyces cerevisiae

To elucidate the roles of genes involved in the cell wall biogenesis and function in Saccharomyces cerevisiae, we isolated and characterized mutants that were lethal in a strain in which the SED1 gene encoding a cell wall mannoprotein was disrupted. Thus, double mutants of SED1 and either MNN9 or MNN10 were unable to grow and YOL155c on a multicopy plasmid could suppress their synthetic lethality. A Yol155cp-GFP fusion protein was found to localize to the cell wall, suggesting that it might also be a cell wall mannoprotein. Subsequently, we analysed the effects of the shut-off of SED1 in a sed1 and mnn9 double mutant: cells after the shut-off showed anomalous cellular morphology and died in the mitotic M phase. From these and other results, we postulate that these genes function cooperatively with each other and in a cell cycle-dependent manner in the biogenesis and maintenance of cell wall in S. cerevisiae.

Increased soluble CD4 molecules and the role of soluble CD4 production in patients with rheumatoid arthritis

We investigated the concentration of soluble CD4 molecules (sCD4) in serum, and the mechanism of sCD4 production from T lymphocytes, in patients with rheumatoid arthritis (RA). The concentration of sCD4 molecules was determined using a solid-phase enzyme-linked immunosorbent assay method. Using reverse transcription polymerase chain reaction (RT-PCR) techniques, we studied the presence of alternatively spliced mRNA encoding the transmembrane site of CD4, and the mRNA encoding a conservative region of the CD4 binding site of the human immunodeficiency virus (HIV), in the serum of RA patients. Levels of sCD4 found in RA patients were higher than in normal controls (199 U/ml compared with 8.4 U/ml, respectively), and correlated with additional medical parameters. The results of RT-PCR suggested that the higher sCD4 levels may be due to shedding from the cell membrane after protease digestion, not to alternative splicing or a reaction to viral binding to sCD4.

Differential selectivity in carbamazepine-induced inactivation of cytochrome P450 enzymes in rat and human liver

Oxidative metabolism of carbamazepine results in covalent binding of its reactive metabolite to liver microsomal proteins, which has been proposed as an important event in pathogenesis of the hypersensitivity reactions to this drug. Although the proposed reactive metabolites are produced by cytochrome P450 enzymes (P450 or CYP), the impact of the formation of unstable metabolites on the enzyme itself has not been elucidated. The present study examines the alteration of P450 enzyme activities during the metabolism of carbamazepine. Liver microsomes from rats and humans were preincubated with carbamazepine in the presence of NADPH, and subsequently assayed for monooxygenase activities representing several P450s. No evidence was obtained for inactivation of CYP2C11, CYP3A, CYP1A1/2 or CYP2B1/2 in rat liver microsomes during the carbamazepine metabolism, whereas the CYP2D enzyme was inactivated in a manner related to the preincubation time. Interestingly, under the same protocol human liver microsomes did not exhibit inactivation of CYP2D6, as well as there being no CYP2C8, CYP2C9 or CYP3A4 inactivation, whereas CYP1A2 was inactivated. Reduced glutathione could not protect against the observed inactivation of the P450s. These results suggest that CYP2D enzyme(s) in rats and CYP1A2 in humans biotransform carbamazepine into reactive metabolites, resulting in inactivation of the enzyme themselves, and raise the possibility that the P450 isoforms participate in toxicity induced by the drug in both animal species.

[A case of intrathoracic extension of retroperitoneal fibrosis]

A 70-year-old man was diagnosed as having retroperitoneal fibrosis 12 years ago. The patient was admitted to our hospital with complaints of fever and left chest pain. On admission, chest radiography revealed left pleural effusion and left pleural thickening. Percutaneous pleural biopsy was performed, and the pleural tissue gave a chronic inflammatory reaction characterized by proliferation of collagen fibers and chronic inflammatory cellular infiltration. Since the retroperitoneal fibrosis had been diagnosed in similar tissue, it was considered that this condition had extended to the pleura. On administration of prednisolone, the intrathoracic lesions and clinical symptoms were improved, but the patient later died of pneumonia. Autopsy showed fibrous pleuritis and chronic fibrosing lung disease. This was an extremely rare case. Prednisolone appears to be useful in the treatment of intrathoracic extension of retroperitoneal fibrosis.

[Three-dimensional computed tomography angiography of coronary artery bypass graft with electron beam tomography]

OBJECTIVES

Assessment of coronary artery bypass graft patency by three-dimensional reconstructed computed tomography angiography (3D-CTA) derived from electrocardiography-gated contrast-enhanced electron beam tomography (EBT) was evaluated.

METHODS

Thirty-nine patients with 99 grafts (45 arterial grafts and 54 venous grafts) underwent 3D-CTA and selective coronary angiography within a 3-week interval. 3D-CTA images of the coronary bypass grafts were compared with the coronary angiography images used as the control.

RESULTS

3D-CTA defined 42 of 44 arterial grafts as patent (sensitivity: 95%), all 47 venous grafts as patent (sensitivity: 100%) and all 7 venous grafts as occlusive (specificity: 100%). The overall sensitivity and specificity were 98% and 88%, respectively.

CONCLUSIONS

3D-CTA is an useful noninvasive technique with adequate sensitivity and specificity to assess coronary artery bypass graft patency.

Cross-genomic analysis of the translational systems of various organisms

We have characterized the genes encoding ribosomal proteins (r-proteins) as well as other translation-related factors of 15 eubacteria and four archaebacteria, and the genes for the mitochondrial r-proteins of Saccharomyces cerevisiae by using the complete genomic nucleotide sequence data of these organisms. In eubacteria, including two species of Mycoplasma, the operon structure of the r-protein genes is well conserved, while their relative orientation and chromosomal location are quite divergent. The operon structure of the r-protein genes in archaebacteria, on the other hand, is quite different from eubacteria and also among themselves. In addition, many archaebacterial r-proteins show similarity to rat cytoplasmic r-proteins. Nonetheless, characteristic features of several genes encoding proteins of functional importance are well conserved throughout the bacterial species including archaebacteria, as well as in S. cerevisiae. We searched for the genes encoding mitochondrial r-proteins in yeast by combining informatics and genetic experiments. Furthermore, we characterized some of the r-proteins genes by exchanging portions between Escherichia coli and S. cerevisiae and performed functional analysis of some of the genes from different evolutionary points of view. Our work may be extended towards phylogenetic analysis of organisms producing secondary metabolites of various sorts.

Mechanism-based inactivation of CYP2C11 by diclofenac

It has been known that diclofenac is biotransformed into chemically reactive metabolites, which bind covalently to liver microsomal proteins, including cytochrome P450 enzyme(s). We have investigated the ability and selectivity of diclofenac to inactivate P450 enzymes. Preincubation of microsomes of untreated rats with diclofenac in the presence of NADPH resulted in time-dependent loss of testosterone 2alpha- and 16alpha-hydroxylation activities. No effect of the preincubation was observed on ethoxyresorufin O-deethylase, pentoxyresorufin O-depentylase, or testosterone 6beta-hydroxylation activity. The time-dependent decreases in testosterone 2alpha- and 16alpha-hydroxylation activities followed the pseudo-first order kinetics and were saturable with increasing diclofenac concentrations. Reduced glutathione was not capable of protecting against the decrease in the enzyme activities. These data establish that a mechanism-based inactivation of CYP2C11 occurs during the oxidative metabolism of diclofenac. The diclofenac concentrations required to achieve the half-maximal rate of inactivation (K(I)) were 3 to 4 microM, which were close to K(m) for the low-K(m) components for diclofenac 4'- and 5-hydroxylation activities (7.29 and 4.43 microM, respectively). Anti-CYP2C11 IgG inhibited diclofenac 4'- and 5-hydroxylation activities, indicating that CYP2C11 is a major isozyme responsible for these aromatic oxidations. The preincubation of microsomes with 4'- or 5-hydroxydiclofenac did not cause a decrease in testosterone 2alpha- or 16alpha-hydroxylation activity, suggesting that neither of the primary metabolites is a precursor of the metabolite that inactivates CYP2C11. Therefore, a highly reactive intermediate(s) inactivating CYP2C11, probably arene-oxide, appears to be generated during the process of diclofenac 4'- and/or 5-hydroxylation. Diclofenac metabolism in human liver microsomes did not cause inactivation of CYP2C9, a major isozyme involved in diclofenac 4'-hydroxylation. Because the human microsomes have high diclofenac 4'-hydroxylation but not 5-hydroxylation activity, importance of the latter pathway in the inactivation is suggested.

[Usefulness of combination post-stress dysfunction and perfusion imaging in technetium-99m-tetrofosmin myocardial scintigraphy]

OBJECTIVES

Myocardial perfusion imaging has lower sensitivity for the diagnosis of coronary artery disease in patients with three-vessel disease. The presence of post-stress dysfunction of the left ventricle, evaluated by electrocardiography(ECG) gated single photon emission computed tomography(SPECT) with a quantitative gated SPECT program, was investigated in patients with coronary artery disease, and also whether combining post-stress dysfunction and myocardial perfusion imaging improved the diagnosis of coronary artery disease.

METHODS

ECG gated technetium-99m-tetrofosmin SPECT was performed using a one day, stress and rest, protocol in 139 patients. SPECT and coronary angiography were performed within 1 month. The coronary artery disease group consisted of 89 patients: 43 with one-vessel disease(1VD), 28 with two-vessel disease(2VD), and 18 with three-vessel disease(3VD). The group with zero-vessel disease(0VD) consisted of 50 patients. According to post-stress and rest ejection fraction(EF) and end-systolic volume (ESV), post-stress dysfunction is defined as follows: rest EF--post-stress EF > or = 5% and post-stress ESV--rest ESV > or = 5 ml.

RESULTS

In the coronary artery disease group, post-stress ESV was larger than rest ESV(37.8 +/- 26.4, 34.0 +/- 24.2 ml, p < 0.001), and post-stress EF was lower than rest EF (61.5 +/- 11.1%, 64.2 +/- 10.8%, p < 0.001). In the 0VD group, ESV and EF were the same for post-stress and rest (25.7 +/- 20.8, 26.2 +/- 21.6 ml, NS; 70.4 +/- 9.5%, 70.0 +/- 9.6%, NS). Post-stress dysfunction was 6.0% in the 0VD group and 30.3% in the coronary artery disease group(p < 0.001). Furthermore, post-stress dysfunction in the 2VD (35.7%) and 3VD(38.9%) groups was higher than that in the 0VD group(p < 0.01, p < 0.01). Sensitivity of coronary artery disease diagnosis by myocardial perfusion imaging was 75%. The combination of post-stress dysfunction and myocardial perfusion imaging improved sensitivity from 75% to 82%(p < 0.05), but reduced the specificity from 92% to 86%(p = 0.08).

CONCLUSIONS

Post-stress dysfunction is a useful parameter for clinical diagnosis of coronary artery disease.

Inactivation of rat cytochrome P450 2D enzyme by a further metabolite of 4-hydroxypropranolol, the major and active metabolite of propranolol

Repetitive administration of propranolol (PL) in rats decreases the activities of cytochrome P450 (CYP) 2D enzyme(s) in hepatic microsomes. We examined the properties of 4-hydroxypropranolol (4-OH-PL) as an inactivator of rat liver microsomal CYP2D enzyme(s) using bunitrolol (BTL) 4-hydroxylation and PL 5- and 7-hydroxylations as indices of CYP2D enzyme activity. Rat microsomal BTL 4-hydroxylase activity was inhibited by the addition of 4-OH-PL to the incubation medium. The inhibition was greater after preincubation of microsomes with 4-OH-PL in the presence of NADPH than in its absence. The type of inhibition kinetics of BTL 4-hydroxylase by 4-OH-PL was changed from a competitive type to a noncompetitive type by the preincubation. The inhibition of rat liver microsomal PL 5- and 7-hydroxylases by 4-OH-PL was blocked efficiently by co-incubation with quinine, a typical inhibitor of rat CYP2D enzyme(s), or to a lesser extent by BTL. However, quinidine, a diastereomer of quinine, did not significantly protect against the enzyme inactivation. The protective capacities of the substrate and inhibitors reflected their affinities for rat CYP2D enzyme(s). BTL hydroxylase was not affected by either 1,4-naphthoquinone or 1,4-dihydroxynaphthalene which are possible metabolites of 4-OH-PL. These results provide further evidence to support the notion that PL is biotransformed by rat CYP2D enzyme(s) to 4-OH-PL, which is further oxidized to a chemically reactive metabolite in the active site. The inactivation of CYP is likely the result of covalent binding of the reactive species to an amino acid residue of the active site.

Protective effect of a synthetic analog of prostaglandin E(1) on the small intestinal damage induced by the administration of methotrexate to rats

Antitumor drugs like methotrexate cause damage to the small intestine, resulting in malabsorption. The present study evaluated this damage by determining the small intestinal absorption of 3-O-methyl-D-glucose (3-OMG) and a poorly absorbable marker, fluorescein isothiocyanate-labeled dextran (FD-4; average molecular mass, 4.4 KDa) using the in vitro everted intestine and in situ intestinal loop techniques. Methotrexate (15 mg/kg body weight) was orally administered to rats once daily for 5 days. A synthetic analog of prostaglandin E(1), OP-1206 (17S,20-dimethyl-trans-Delta(2)-prostaglandin E(1); 0.5 microg/kg body weight) was orally administered to rats twice a day for 5 days. The absorption clearance of FD-4 via the small intestine of the methotrexate-treated rats increased marked, but that of the methotrexate- and OP-1206-treated rats was significantly lower than that of the rats treated only with methotrexate. The absorption clearance of [(3)H]-3-OMG via the small intestine of the methotrexate-treated rats fell markedly, but that of the methotrexate- and OP-1206-treated rats was significantly greater than that of the rats treated only with methotrexate. The changes in AUC values of FD-4 and [(3)H]-3-OMG obtained from in situ intestinal loop experiment showed the same trends as those seen in the absorption clearance from the in vitro everted intestine experiment. These results show that OP-1206 alleviates the methotrexate-induced damage to the small intestine of rats.

Recurrent giant longitudinal duodenal ulcer with massive hemorrhage in a Helicobacter pylori-negative patient

A 67-year-old man, in whom a linear ulcer running from the duodenal bulb to the descending part had been noted 3 years previously, was admitted to our hospital because of abdominal pain and melena. Duodenoscopy revealed a bleeding giant longitudinal ulcer, which was more extensive than before. Tests for Helicobacter pylori (Hp) were negative. The ulcer was cured by endoscopic hemostasis and repeated blood transfusions. Attention must be paid to Hp-negative post-bulbar duodenal ulcers because of the frequent complications including hemorrhage.

Analysis of 20-year follow-up study of LVP regimen for adult acute lymphoblastic leukemia

In an attempt to develop a new intensive chemotherapy for adults with untreated acute lymphoblastic leukemia (ALL), 3 sequential programs were designed for 62 patients (age range, 15 to 74 years; median age, 32 years) consisting of the LVP-79 (1979-1984, 27 patients), LVP-85 (1984-1986, 14 patients), and LVP-87 (1987-1989, 21 patients) regimens. The influence of clinical and biologic characteristics on the patient outcome was also examined. L-asparaginase (L-asp), vincristine, and prednisolone, defined collectively as LVP, were administered for induction chemotherapy in all protocols. After achieving complete remission (CR), patients underwent 2 years of multi-agent consolidation, intensification, and maintenance therapy consisting of various combinations. No significant differences were noted between the 3 groups regarding CR rate or survival. In total, 47 of 62 patients (75.8%) achieved CR. The median overall survival (OS) and median CR durations were 550 days and 341 days, respectively. Overall, the estimated survival rate at 20 years was 18.1%. The disease-free survival rate at 20 years was 26.2%. According to univariate analysis, the most favorable pretreatment characteristic for achieving CR was age. A younger age (<40 years of age), platelet count >30 x 10(9)/L, having L1 morphology (French-American-British [FAB]classification subtype), female sex, and the absence of chromosomal abnormalities also helped improve survival rate. According to multivariate analysis, presence of Ph chromosome was found to be a major influencing factor for OS. Although higher doses of L-asp were administered than those used in previous studies, the adverse effect of L-asp was rarely identified. Therefore, it should be considered one of the key drugs for treatment of adult ALL. Further strategies still need to be developed to obtain better survival in adult ALL.

Characteristics of transport of fluoresceinated methotrexate in rat small intestine

The small intestinal damage induced by the methotrexate (MTX) treatment results in malabsorption and diarrhea. The fluoresceinated methotrexate (F-MTX) may possibly be useful to study such effects of MTX on the small intestine. The purpose of this study is to characterize the transport of F-MTX in the small intestine in order to use it as a membrane transport and cellular marker of MTX. The transport of F-MTX in the rat small intestine (jejunum) was examined in the in vitro everted segments of the intestine. The uptake was pH-dependent and showed a maximal effect at pH 6.0, which was the same as the results of MTX previously reported. Further, it was temperature-dependent and was inhibited by metabolic inhibitors, dinitrophenol and sodium azide, and by MTX. The transport kinetics at pH 6.0 in the mucosal solution and at pH 7.4 in the serosal solution was saturable with Km of 0.48 +/- 0.23 microM and Vmax of 0.66 +/- 0.24 pmol/cm/min and in addition, the passive diffusion was observed there. These results suggested that the transport of F-MTX was energy-dependent and was mediated by the same transporter as that of MTX, although, in addition to it, other transport mechanism might contribute to the F-MTX transport. Therefore F-MTX will be of great use to investigate the MTX transport system in the normal and diseased states of small intestine, using various fluorescence techniques like visualization of membrane-associated transport proteins.

Two types of HKT transporters with different properties of Na+ and K+ transport in Oryza sativa

It is thought that Na+ and K+ homeostasis is crucial for salt-tolerance in plants. To better understand the Na+ and K+ homeostasis in important crop rice (Oryza sativa L.), a cDNA homologous to the wheat HKT1 encoding K+-Na+ symporter was isolated from japonica rice, cv Nipponbare (Ni-OsHKT1). We also isolated two cDNAs homologous to Ni-OsHKT1 from salt-tolerant indica rice, cv Pokkali (Po-OsHKT1, Po-OsHKT2). The predicted amino acid sequence of Ni-OsHKT1 shares 100% identity with Po-OsHKT1 and 91% identity with Po-OsHKT2, and they are 66-67% identical to wheat HKT1. Low-K+ conditions (less than 3 mM) induced the expression of all three OsHKT genes in roots, but mRNA accumulation was inhibited by the presence of 30 mM Na+. We further characterized the ion-transport properties of OsHKT1 and OsHKT2 using an expression system in the heterologous cells, yeast and Xenopus oocytes. OsHKT2 was capable of completely rescuing a K+-uptake deficiency mutation in yeast, whereas OsHKT1 was not under K+-limiting conditions. When OsHKTs were expressed in Na+-sensitive yeast, OsHKT1 rendered the cells more Na+-sensitive than did OsHKT2 in high NaCl conditions. The electrophysiological experiments for OsHKT1 expressed in Xenopus oocytes revealed that external Na+, but not K+, shifted the reversal potential toward depolarization. In contrast, for OsHKT2 either Na+ or K+ in the external solution shifted the reversal potential toward depolarization under the mixed Na+ and K+ containing solutions. These results suggest that two isoforms of HKT transporters, a Na+ transporter (OsHKT1) and a Na+- and K+-coupled transporter (OsHKT2), may act harmoniously in the salt tolerant indica rice.