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Biomedical subjects

N Narita

Publications and source records attributed to N Narita.

At least 19 recordsLinked to original sources
PubMed2001

Enhanced low shear stress induced platelet aggregation by Shiga-like toxin 1 purified from Escherichia coli O157.

The effect of Shiga-like toxin 1 (Stx1) produced by Escherichia coli O157 on platelets was studied with an argon laser light-assisted shear-induced platelet aggregometer and with binding assays. Stx1 markedly enhanced the platelet aggregation under low shear stress but did not affect it under high shear stress. Minimal concentration of Stx1 required for the enhancement was 0.25 ng/ml, and almost maximal enhancement was observed at a final concentration of > or =2.5 ng/ml. This enhanced platelet aggregation disappeared after leukocyte depletion from normal platelet-rich plasma with a specific filter. In contrast, a standard platelet aggregometer was unable to detect this enhanced platelet aggregation in either the presence or the absence of ADP. 125I-labeled purified Stx1 did not specifically bind to normal washed platelets depleted of leukocytes, and thin-layer chromatographic analysis of glycolipids extracted from normal platelet lysates also confirmed that leukocyte-depleted normal platelets lack Stx1-specific receptor globotriaosylceramide (Gb3). Supernatant from the monocyte suspension stimulated with Stx1 exhibited the enhanced low shear stress induced platelet aggregation, but that from the polymorphonuclear cell suspension did not. Several cytokines produced from monocytes reproduced this event in vitro. Further, plasmas from six out of seven patients with hemolytic uremic syndrome (HUS) had activity similar to the purified Stx1. This activity was almost totally impaired after treatment of HUS plasmas with Gb3 in accord with reduction of plasma Stx1 levels. Taken together, these results indicate that platelets lack Gb3, and Stx1 appears to modulate platelet aggregation in an indirect fashion, presumably by the release of cytokines or chemical compounds from the target tissues.

Bacterial Toxins↗
PubMed2001

Mechanisms of action of the novel sulfonamide anticancer agent E7070 on cell cycle progression in human non-small cell lung cancer cells.

E7070 is a novel sulfonamide antitumor agent that exhibits potent antitumor activity in vitro and in vivo. This compound affects cell cycle progression in human tumor cells. To elucidate the mechanisms by which E7070 inhibits tumor cell growth, we established and characterized an E7070-resistant subline, A549/ER, from a human non-small cell lung cancer cell line A549. Flow cytometric analyses demonstrated an increase in G0/G1 and a decrease in S phase populations in cells treated with E7070 at 20 or 100 microg/ml for 24 h. Longer exposure to E7070, i.e. 48 and 72 h, increased the G2/M phase fraction in A549 cells. These inhibitory actions of E7070 on cell cycle progression were not observed in A549/ER cells. E7070 inhibited the phosphorylation of pRb, decreased expressions of cyclin A, B1, CDK2, and CDC2 proteins, and suppressed CDK2 catalytic activity with the induction of p53 and p21 proteins in A549 cells but not in A549/ER cells. Taken together, these results suggest that E7070 exerts its antitumor effects by disturbing the cell cycle at multiple points, including both the G1/S and the G2/M transition, in human lung cancer cells.

Antineoplastic Agents↗
PubMed2001

The effect of nutritional status on morbidity in COPD patients undergoing bilateral lung reduction surgery.

BACKGROUND: Although candidates for lung reduction surgery (LRS) include malnourished patients with severe chronic obstructive pulmonary disease (COPD), the impact of preoperative nutritional status on surgical outcome has not been clearly elucidated. METHODS: We investigated the relationship between preoperative nutritional status and postoperative morbidity in 23 consecutive patients undergoing LRS. The percentage of ideal body weight (%IBW) and body mass index (BMI) were calculated, and fat-free mass (FFM) and fat mass (FM) were measured using a bioelectrical impedance analyzer. FFM and FM were expressed as height-normalized indices, FFM index [FFM (kg)/height (m)(2), or FFMI] and FM index [FM (kg)/height (m)(2), or FMI]. Serum levels of total protein and albumin were also determined. RESULTS: 8 patients had major complications. Preoperative %IBW and FFMI were significantly lower among patients with major complications, while no significant differences were observed in pulmonary function, FMI or serum protein. The complication rate was significantly higher among patients with low FFMI (FFMI < or = 16) but not with low %IBW or BMI. CONCLUSION: These results suggest that FFM depletion is an excellent predictor of unacceptable postoperative complication following LRS.

Aged↗
PubMed2001

Distribution of muscle mass and maximal exercise performance in patients with COPD.

STUDY OBJECTIVE: To investigate the distribution of reduction in lean body mass (LBM) and whether LBM in legs (LBMlegs) can be a determinant of maximal exercise performance in COPD patients. METHODS: Thirty-eight male outpatients with COPD (mean +/- SD FEV1, 47.4 +/- 24.0% of predicted) who underwent complete pulmonary function testing were classified into two groups according to FEV1 expressed as a percentage of predicted value. Group A comprised 21 patients with mild-to-moderate airflow limitation (FEV(1) > or =35% predicted), and group B comprised 17 patients with severe airflow limitation (FEV1 < 35% predicted). LBM, which represents skeletal muscle mass, was measured by dual energy x-ray absorptiometry (DXA) and was assessed separately in arms, legs, and trunk. Maximal oxygen uptake VO2max was measured during maximal exercise on a cycle ergometer. RESULTS: LBM in each region was expressed as a percentage of ideal body weight (IBW). LBM in arms (LBMarms)/IBW, LBMlegs/IBW, and LBM in trunk (LBMtrunk)/IBW were significantly depleted in group B compared with group A (p < 0.01). LBMlegs expressed as a percentage of total LBM (LBMlegs/total LBM) was significantly lower in group B (p < 0.05), although there was no significant difference in LBMarms/total LBM and LBMtrunk/total LBM between the two groups. VO2max correlated significantly with LBMlegs/IBW in group A, but not in group B. By stepwise regression analysis, LBMlegs/IBW appeared to be a significant predictor of VO2max in group A, while not in group B. CONCLUSION: LBMlegs was a significant predictor of maximal exercise performance in patients with mild-to-moderate airflow limitation, but not in patients with severe airflow limitation who had disproportional reduction in LBMlegs.

Absorptiometry, Photon↗
PubMed2001

Serotonin transporter gene variation is a risk factor for sudden infant death syndrome in the Japanese population.

OBJECTIVE: Serotonin (5-HT) in the nervous system is a major factor in facilitation of the brain center for respiration. Variations in the promoter region of the 5-HT transporter (5-HTT) gene have been shown to potentially regulate 5-HT activity in the brain. Therefore, we aimed to identify the possibility that specific allele variants of the 5-HTT gene can be found as a genetic background for sudden infant death syndrome (SIDS). METHODS: Polymorphisms in the 5' regulatory region of the 5-HTT gene were determined in genomic DNA obtained from 27 SIDS victims and 115 age-matched health control participants. RESULTS: There were significant differences in genotype distribution and allele frequency of the 5-HTT promoter gene between SIDS victims and age-matched control participants. The L and XL alleles were more frequently found in SIDS victims than in age-matched control participants. CONCLUSION: Efficiency in the transportation of 5-HTT with the L allele is known to be higher than that with the S allele. The excitatory function by 5-HT is considered to be lower in the respiratory center of individuals with the L allele compared with those with S allele. The XL allele variant has shown another novel biological risk factor for SIDS.

Carrier Proteins↗
PubMed2001

[Effective use of camostat mesilate for chronic disseminated intravascular coagulation complicated by thoracoabdominal aortic aneurysm].

A 73-year-old man who had been receiving treatment for hypertension and angina pectoris was admitted to hospital following a transient ischemic attack. He was diagnosed as having chronic disseminated intravascular coagulation (DIC) complicated by a thoracoabdominal aortic aneurysm, and was treated with heparin sodium and a protease inhibitor. Although the DIC was controlled, the patient had to remain hospitalized in order to receive the medication by continuous infusion. Therefore, the heparin sodium and protease inhibitor were replaced by camostat mesilate, a drug suitable for oral administration and widely used for treatment of chronic pancreatitis. The drug proved effective for the chronic DIC, thus allowing the patient to receive regular treatment on an outpatient basis, and improving his quality of life.

Administration, Oral↗
PubMed2001

[Usefulness of three-dimensional color Doppler sonography for the differential diagnosis of subpleural lesions].

The purpose of our investigation was to assess the usefulness of three-dimensional color Doppler sonography (velocity mode and power mode) for the differential diagnosis of subpleural lesions. Thirty lesions (11 pneumonias, 5 lung abscesses, 11 primary lung cancers, 3 metastatic lung cancers) were examined. Three-dimensional images were reconstructed by a maximum intensity projection method. Three-dimensional representations of intralesional blood flow became available for all lesions approximately 11 seconds after scanning. In every case, the entire vasculature of the tumor, the pneumonia, the abscess, or the inflamed region of the lung was appreciated more easily from three-dimensional images than from two-dimensional images. We classified the color flow pattern of subpleural lesions depicted by color flow imaging into seven groups. Color flow was depicted better by the three-dimensional color Doppler power mode than the velocity mode. Three-dimensional color flow patterns observed in power mode, patterns of the pneumonias and the lung cancers differed significantly. Our results suggest that the three-dimensional color Doppler power mode is useful for the differential diagnosis of subpleural lesions.

Adult↗
PubMed2001

[Epidural blood patch for the treatment of intracranial hypotension due to cerebrospinal fluid leakage after thoracic spine surgery].

We report a case of a 44-year-old woman successfully treated by an epidural blood patch for intracranial hypotension due to cerebrospinal fluid (CSF) leakage into the thoracic cavity after thoracic spine surgery. The patient was admitted to our hospital with the complaint of postural headaches. She had received anterior thoracic instrumentation for thoracic disc herniation four months earlier. Lumbar puncture demonstrated low CSF pressure, and Gd-enhanced MR images displayed diffuse dural enhancement. Accordingly, she was diagnosed as having intracranial hypotension. 111In-DTPA cisternography revealed a CSF leakage into the left thoracic cavity, possibly caused by dural laceration during thoracic spine surgery. To avoid the risk of direct surgery, we performed epidural blood patch; 3 ml of autologous blood was injected into the epidural cavity. Postoperatively postural headaches immediately disappeared. MRI taken one year later revealed disappearance of diffuse dural enhancement, and 111In-DTPA cisternography revealed no CSF fluid leaks. Epidural blood patch seems to be a choice of treatment for CSF leak after spinal surgery.

Adult↗
PubMed2001

[A study on relation between active pulmonary tuberculosis and underlying diseases].

A study was made on the relation between active pulmonary tuberculosis and underlying diseases in 119 tuberculosis patients. Out of total 119 patients, 87 patients (73.1%) had underlying diseases. The most common underlying disease was diabetes mellitus in 34 patients (39.1%), followed by HCV (+) chronic hepatitis, sequela of cerebral infarction, hypertension and gastric ulcer. In patients who had underlying diseases, the mean age was higher, proportion of sputum smear positive cases was higher, albumin was lower, and period until sputum culture negative conversion was longer. In patients who had diabetes mellitus, proportion of cases with cavity on chest X-P was higher, and in patients who had sequela of cerebral infarction or hypertension, mean age was higher. In patients who had diabetes mellitus and whose HbA1C was > or = 9%, proportion of smear positive cases was higher, albumin was lower and period until culture negative conversion was longer than in patients who had diabetes mellitus and whose HbA1c was < 9%, suggesting that control of blood sugar in diabetes mellitus related to severity of pulmonary tuberculosis. In patients who had diabetes mellitus and whose albumin was < 3 g/dl, period until culture negative conversion was longer than in patients who had diabetes mellitus and whose albumin was > or = 3 g/dl. In patients who had underlying diseases, these diseases caused decline of tuberculous immunity and nutritional disturbance represented by lower albumin also promoted decline of tuberculous immunity. It is suggested that the underlying diseases affected the onset and progression of pulmonary tuberculosis.

Adult↗
PubMed2000

Mechanism of action of aragusterol a (YTA0040), a potent anti-tumor marine steroid targeting the G(1) phase of the cell cycle.

Aragusterol A (YTA0040), isolated from the Okinawan marine sponge of the genus Xestospongia, is a potent anti-tumor marine steroid that possesses a unique structural component. This compound showed broad-spectrum anti-proliferative activity against a panel of 14 human cancer cell lines (IC(50) = 0.01-1.6 microM). P-glycoprotein-mediated, multidrug-resistant cells showed cross-resistance to YTA0040 cells, whereas cisplatin-resistant non-small-cell lung-cancer (NSCLC) sublines showed a collateral sensitivity to YTA0040. In transplantable murine tumor models, YTA0040 displayed a broad spectrum and high degree of anti-tumor activity when administered i.p. or p.o. (life span T/C = 135-234%). In P388 murine leukemia cells, YTA0040 caused dose- and time-dependent suppression of nucleic acid and protein synthesis, with protein synthesis being more potently and rapidly inhibited than nucleic acid synthesis. Flow-cytometric analysis revealed that YTA0040 blocked the entry of human NSCLC-derived A549 cells into S phase, leading to arrest in the G(1) phase of the cell cycle. Western blot analysis demonstrated that YTA0040 caused a dose-dependent decrease in the levels of expression of hyperphosphorylated pRb and cyclin A in A549 cells. The level of p53 protein expression was decreased by YTA0040 treatment. A higher concentration of YTA0040 down-regulated the levels of expression of CDK2, CDK4, cyclin D1 and cyclin E. These findings indicated that YTA0040 arrested human NSCLC cells in late G(1) phase of the cell cycle through inhibition of pRb phosphorylation. Inhibition of pRb phosphorylation by YTA0040 resulted from down-regulation of levels of expression of the CDKs and cyclins involved in the G(1)/S transition and not from induction of p53 and/or the CDK inhibitor p21.

Animals↗
PubMed2000

Defective T cell function for inhibition of growth of Mycobacterium avium-intracellulare complex (MAC) in patients with MAC disease: restoration by cytokines.

To define the immunopathologic mechanism underlying pulmonary Mycobacterium avium-intracellulare complex (MAC) disease in patients without AIDS, the ability of CD4(+) and gammadelta T cells to induce growth inhibition of MAC in monocytes was compared between patients and healthy control subjects. T cell-dependent growth inhibition and production of interferon-gamma and macrophage colony-stimulating factor decreased in patients. CD4(+) T and gammadelta T cells from patients were equally defective in inducing anti-MAC activity. The combination of these cytokines restored the ability of patients' T cells to control MAC growth. In experiments with allogeneic cocultures of gammadelta T cells and infected monocytes from patients and control subjects, healthy control T cells could augment growth inhibition of MAC in monocytes from patients, whereas patients' T cells could not, even in the presence of healthy control monocytes. These results indicate that the defect in T cells may be associated with impaired protective immunity against MAC in these patients.

Aged↗
PubMed2000

Ectopic p16(ink4) expression enhances CPT-11-induced apoptosis through increased delay in S-phase progression in human non-small-cell-lung-cancer cells.

A tumor-suppressor gene, p16(INK4), which is deleted or mutated in tumors, regulates cell-cycle progression through a G(1)-S restriction point by inhibiting CDK4(CDK6)/cyclin-D-mediated phosphorylation of pRb. We have found that ectopic p16(INK4) expression increased cellular sensitivity of human non-small-cell-lung-cancer (NSCLC) A549 cells to a selective growth-inhibitory effect induced by the topoisomerase-I inhibitor 11, 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxy camptothecin (CPT-11) in vitro. In this study, we observed enhanced apoptosis characterized by DNA fragmentation in A549 cells transfected with p16(INK4) cDNA (A549/p16-1) and treated with CPT-11. This apoptosis was suppressed by the inhibitor of interleukin-1beta-converting enzyme (ICE/caspase-1) or ICE-like proteases, Z-Asp-CH2-DCB, as determined by DNA fragmentation and proteolytic cleavage of poly(ADP-ribose) polymerase, a natural substrate for CPP32/caspase-3. In A549/p16-1 cells, cytosolic peptidase activities that cleaved Z-DEVD-7-amino-4-trifluoromethylcoumarin increased during CPT-11-induced apoptosis and were suppressed by a highly specific caspase-3 and caspase-3-like inhibitor, Z-DEVD-fluoromethylketone. These findings indicate that p16(INK) is positively involved in the activation pathway of the caspase-3 induced by CPT-11. The increased delay in S-phase progression and subsequent induction of apoptosis were observed in CPT-11-treated A549/p16-1 cells on the basis of DNA histograms. Specific down-regulation of the cyclin-A protein level in A549/p16-1 cells was observed after CPT-11-treatment, whereas cyclin B, cdk2, and cdc2 protein levels were unaffected. These results suggest that ectopic p16(INK4) expression inappropriately decreases cyclin A and thereby terminates CPT-11-induced G(2)/M accumulation, which is followed by increased apoptosis in p16(INK4)-expressing A549 cells.

Antineoplastic Agents, Phytogenic↗