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Biomedical subjects

M Hamada

Publications and source records attributed to M Hamada.

At least 91 records · Page 5Linked to original sources
PubMed1999

Evidence of simple intramolecular rearrangement at polymer end groups in secondary ion mass spectrometry.

Polystyrenes with various end groups were analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS). These end groups were obtained by termination of the active anionic group by sulfonate or chlorosilane derivatives. Characteristic end group fragments for each sulfonate derivative were observed. On the one hand, for PS capped by methyl sulfonate, or -(CH(2))(4)-O-SO(2)-CH(3), almost complete end group fragment is observed at m/z 95 and a [O-SO(2)-CH(3)](-) molecular structure. On the other hand, when PS is terminated by silyl methyl sulfonate, or -Si(CH(3))(2)-(CH(2))(3)-O-SO(2)-CH(3), the most characteristic fragment in the fingerprint secondary ion mass spectrum is located at m/z 153 with [Si(CH(3))(2)-O-SO(2)-CH(3)](+) and the complete end group peak, [Si(CH(3))(2)-(CH(2))(3)-O-SO(2)-CH(3)](+), at m/z 201, is absent. According to the molecular structure, characteristic end group secondary ions can be emitted as complete or rearranged fragments. Various silylalkyl alcohol or sulfonate functionalities are analyzed and fragmentation pathways are discussed. To our knowledge, this is the first time that such rearrangement at silyl functions has been observed and demonstrated in fingerprint secondary ion mass spectra. Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

A possible mechanism of TPA-mediated downregulation of neurotrophin-3 gene expression in rat cultured vascular smooth muscle cells.

We have previously reported that in cultured rat vascular smooth muscle cells (VSMCs), neurotrophin-3 (NT-3) gene expression was suppressed by TPA (12-O-tetradecanoyl phorbol-13-acetate), which induces an AP-1 transcription factor. In the present study, to clarify the mechanism for TPA-mediated downregulation of NT-3 gene expression, effects of cycloheximide and dexamethasone (Dex) on the TPA-mediated downregulation were examined in VSMCs. Pretreatment with cycloheximide, an inhibitor of protein synthesis, or simultaneous treatment with Dex, an inhibitor of AP-1, suppressed the TPA-mediated downregulation of NT-3 gene expression. Furthermore, co-transfection of c-fos and c-jun expression vectors into VSMCs resulted in decrease in the NT-3 gene expression. The present findings suggest that TPA-induced AP-1 de novo synthesis causes the downregulation of NT-3 gene expression in VSMCs.

Animals↗
PubMed1999

Chiral separation of dansyl-DL-amino acids with micellar systems containing copper (II) ion and N-n-dodecyl-L-proline in electrokinetic capillary chromatography.

Enantiomers of dansylated DL-amino acids were resolved by chiral copper (II)-N-n-dodecyl-L-proline (1) complexes incorporated in micelles of sodium dodecyl sulfate (SDS) in electrokinetic capillary chromatography (EKC). This resolution is caused by formation of diastereomeric ternary complexes consisting of chiral ligand 1, central copper (II) ion and enantiomeric amino acid derivatives in micellar phase. However, the resolution was not observed when SDS with an anionic polar head grop was replaced with dodecyl trimethylammonium brode (DTMAB) with a cationic polar head group. The ratio between copper (II) ion and 1 in the complex in either SDS or DTMAB was measured by UV-visible spectra, which respond to the d-d transition of copper (II). Mechanism of separation should be discussed in terms of effect of surfactant structures on constitution of copper (II) ion and 1 in the micellar phase and that of arene substituent structures linked to sulfonamide units in amino acid derivatives to be separated.

Amino Acids↗
PubMed1999

Establishment of T-helper type 2 clone-induced eosinophilia in mouse conjunctiva.

Eosinophil infiltration is one of the aspects of the inflammatory response to an allergen. The aim of this study was to establish T-helper type-2 (Th2)-induced conjunctival eosinophilia in mice to evaluate the effect of anti-allergic drugs. Th2 clone, D10.G4.1. (D10) with its specific antigen, conalbumin was co-injected into conjunctival tissue in mice. At 3-6 hr after D10 injection, eosinophil and neutrophil recruitment into conjunctival tissue was observed. Cellular infiltration into conjunctival tissue reached a maximum level between 24-48 hr after D10 injection. The number of eosinophils which infiltrated after 24 hr was dose dependent on T cell injection titer from 1x10(4), 1x10(5)to 1x10(6)cells site-1. The ratio of eosinophils to neutrophils at 24 hr after D10 cell (1x10(5)cells site-1) injection was about 9 to 1. The eosinophil infiltration into conjunctival tissue was significantly reduced by the intraperitoneal administration of anti-IL-5 monoclonal antibody (100 micrograms animal-1). Anti-IL-4 monoclonal antibody (500 micrograms animal-1) partially inhibited eosinophilia. The combined inhibitory effect of anti-IL-4 and anti-IL-5 monoclonal antibodies was larger than the inhibitory effect of anti-IL-5 monoclonal antibody alone. In conclusion, a Th2-induced mouse conjunctival eosinophilia model was established in which D10 activation results in IL-4 and IL-5 release. These cytokines elicit eosiniophil infiltration. This response shows that the model will be effective for screening candidates of anti-allergic drugs.

Animals↗
PubMed1999

Diagnosis of Thrombus and Blood Flow in Aortic Aneurysm Using Tagging Cine Magnetic Resonance Imaging.

In order to diagnose thrombus and to evaluate blood flow in aortic diseases, we investigated the usefulness of tagging cine magnetic resonance imaging (MRI) in patients with aortic aneurysm and aortic dissection. Six abdominal aortic aneurysms (AAA), two aortic arch aneurysms, and three aortic dissections were examined using tagging cine MRI. Linear tagging bands were 3 or 5 mm wide and established to the long and short axial images of the aortic lesions. Tagging bands were confirmed as the low-intensity signal bands in all patients. The parts of tagging bands of the intraaortic thrombus did not move, whereas the parts of tagging bands of the intraaortic blood flow moved and faded as time passed. Intraaortic thrombi were diagnosed in eight patients (six AAA, one aortic arch aneurysm, and one aortic dissection) in accordance with the stain of the parts of tagging bands. In patients with aortic dissection, the parts of tagging bands in the false lumen moved slowly, whereas the parts of tagging bands in the true lumen moved quickly. Tagging cine MRI has been shown to be useful in the diagnosis of thrombus and blood flow in aortic diseases.

Journal Article↗
PubMed1999

Rapidly enlarging esophageal duplication cyst.

We report a rare esophageal duplication cyst, in a 12-year-old girl. The cyst had enlarged rapidly within 2 years. In December 1997, on admission, computed tomography and magnetic resonance imaging demonstrated a cystic mass in the pleural cavity. We resected the cyst and the adjacent lung. Histopathological examination revealed an esophageal duplication cyst. Her presenting symptoms of fever and cough may have been related to infection of the cyst.

Child↗
PubMed1999

Cardiomyocyte apoptosis with enhanced expression of P53 and Bax in right ventricle after pulmonary arterial banding.

The aim of this study is to investigate whether the cardiomyocyte apoptosis is induced after experimental right-sided pressure overload and whether the expression of proapoptotic factor is altered or not. Ten-week-old male Sprague-Dawley rats were subjected to right ventricular overload by experimental coarctation of the main pulmonary artery. In pulmonary artery-banded rats, TUNEL method revealed that positive nuclei were observed in cardiomyocytes exclusively in the right ventricle, and Northern blot analysis showed that p53 mRNA level in the right ventricle was 6.2-fold higher at the day 1 than that in sham-operated rats and its level decreased gradually. Bax mRNA in the right ventricle was also increased 3.3-fold at the day 1 in pulmonary artery-banded rats and also gradually decreased. The immunohistochemical study revealed that the immunoreactivity of P53 and Bax was observed exclusively in the right ventricle of the pulmonary artery-banded group. These results demonstrated that the occurrence of TUNEL-positive cardiomyocytes in the acute pressure overload was accompanied by the enhanced expression of apoptosis inducers. It is suggested that acute pressure overload is a potent apoptotic stimulus for cardiomyocytes.

Animals↗
PubMed1999

A progression to dermatofibrosarcoma protuberans with a fibrosarcomatous component: a special reference to the chromosomal aberrations.

Dermatofibrosarcoma protuberans (DFSP) with fibrosarcomatous areas (DFSP-FS) is differentiated from ordinary DFSP by its unfavourable prognosis. We carried out sequential analysis of numerical chromosomal abnormalities in two cases of DFSP during their progression to metastatic disease with FS areas (DFSP-M-FS). They were compared with nine cases of ordinary DFSP and three cases of DFSP-FS, but without metastases. Numerical chromosomal changes were examined by fluorescence in situ hybridization (FISH) using alpha-satellite centromeric probes for chromosomes 1, 8, 11 and 17. Numerical imbalances of chromosome 1 were not clarified. A gain of chromosome 8 was demonstrated in the two cases of DFSP-M-FS. A gain of chromosome 11 was observed in one of the two cases of DFSP-M-FS and in one case of DFSP-FS. A gain of chromosome 17 was demonstrated in both metastatic tumours and in recurrent tumours in two cases of DFSP-M-FS, in addition to two cases of DFSP-FS and four cases of ordinary DFSP with recurrent tumours or large tumours. This study raised the hypothesis that a gain of chromosome 17 developed in recurrent or large-sized DFSP, which occurs in high-risk groups with the possibility of a progression to FS.

Adolescent↗
PubMed1999

Rest-redistribution thallium-201 myocardial scintigraphic study in cardiac amyloidosis.

BACKGROUND: Histopathological study in amyloid heart demonstrates that myocyte destructed by the extracellular deposition of amyloid protein together with viable myocyte is present. We hypothesized that rapid thallium washout may be found in amyloid heart as in regions which have a mixture of viable myocyte and scar tissue in patients with myocardial infarction. Thus, the purpose of this study was to evaluate the extent and severity of myocardial damage due to amyloid deposits using the washout rate of the tracer on rest-redistribution thallium-201 (201Tl) myocardial scans in cardiac amyloidosis patients. METHODS: Rest-redistribution 201Tl myocardial scintigraphy was performed in 5 patients with biopsy-proved systemic amyloidosis with cardiac involvement (amyloidosis group). The initial and delayed images were obtained 15 min and 4 h, respectively, after intravenous injection of the tracer of 111 MBq. Washout rate of the tracer was calculated. Twelve patients with no apparent heart disease served as controls (control group). RESULTS: Mean washout rate of the whole heart was higher in the amyloidosis group than in the control group (56 +/- 9% vs 36 +/- 6%, p < 0.001). Particularly, 4 of the 5 patients in the amyloidosis group presented a very high rate of thallium clearance which ranged from 57 to 61%, and died in less than a year. In the remaining 1 patient who had a normal washout rate of the tracer in the first study, it changed from 40 to 53% during the 5-year follow-up period. CONCLUSIONS: Washout rate in the setting of rest and delayed 201Tl images may represent the severity of amyloid depositions in the myocardium and may provide prognostic information.

Aged↗
PubMed1999

Effect of antihypertensive therapy on aortic distensibility in patients with essential hypertension: comparison with trichlormethiazide, nicardipine and alacepril.

To assess the effect of antihypertensive drugs on aortic distensibility, we evaluated the aortic distensibility of 33 hypertensive patients before and after antihypertensive treatment by using cine magnetic resonance imaging. Thirty three hypertensive patients were divided into three groups and treated for 12 weeks with 2-4 mg trichlormethiazide per day (n = 10), 80 mg nicardipine per day (n = 13) and 50 mg alacepril per day (n = 10). There were no significant differences in mean age and mean blood pressure among the three groups. Cine magnetic resonance was performed at ascending and descending aortic levels. Aortic area was measured at the maximum and minimum frames. The effect of antihypertensive therapy on aortic distensibility was evaluated as the percent change from before treatment to after treatment. There were no significant differences in pulse pressure before and after treatment with trichlormethiazide, nicardipine and alacepril. After treatment with these drugs, mean blood pressure in all groups decreased (trichlormethiazide and nicardipine, P < .01; alacepril, P < .05), (the maximum area--the minimum area) and aortic distensibility in all groups increased significantly (each P < .01). Percent changes in aortic distensibility after treatment were significantly higher with nicardipine (ascending, 346.6 +/- 255.9%; descending, 338.8 +/- 246.5%, each P < .05) and alacepril (ascending, 369.7 +/- 238.8%, P < .05; descending, 306.9 +/- 123.3%, P < .01) than with trichlormethiazide (ascending, 146.0 +/- 139.6%; descending, 129.3 +/- 97.5%). In conclusion, nicardipine and alacepril have a beneficial effect on aortic distensibility.

Age Factors↗
PubMed1999

Morphological changes induced by administration of a Na+,K+-ATPase inhibitor in normal and hydropic inner ears of the guinea pig.

The objective of this study was to determine the effects of ouabain, a Na+,K+-ATPase inhibitor, in inner ears. Administering ouabain locally through the round window and vestibule, resulted in degenerative changes in cochlear and vestibular sensory cells and limbal fibrocytes, but the stria vascularis and spiral ligament were less affected. The position of Reissner's membrane was rarely changed. Vacuolar spaces in the sensory epithelia of cristae, maccula utriculi and macula sacculi increased in number. Nystagmus was a common occurrence with or without demonstrating degeneration of vestibular sensory cells. By administering ouabain systemically, the course of developing endolymphatic hydrops could not be altered in the ears with endolymphatic duct blockage. Edema of nerve endings of inner hair cells and vestibular sensory cells was frequently observed with administration of a high concentration of ouabain in both normal and hydropic ears, but edema was reversible. Degeneration of some vestibular sensory cells were observed in hydropic ears with a long survival time. The mechanism of selective sensitivity or non-sensitivity of inner ear tissues to ouabain is discussed.

Animals↗
PubMed1999

The rebound phenomenon of glycerol-induced changes in the endolymphatic space.

Volumetric changes of the scala media were histologically investigated in normal guinea pigs to see whether glycerol-induced volumetric change of the scala media followed a biphasic course similar to the auditory threshold in the glycerol test. Glycerol was administered orally in a 12 ml/kg dose. The volume of the scala media was assessed by examining the cross-sectional area of the scala media in the mid-modiolar sections of the cochlea. Histological study revealed that the time-course of the change in the volume of the scala media after glycerol intake showed biphasic changes. Specifically, the early phase of the glycerol effect is a decrease in endolymph volume. The volume of the scala media significantly decreased by 11.4+/-2.9% 2 h after glycerol intake. Thereafter, the volume began to increase, and reached its peak 6-12 h after intake. In addition, the volume of the scala media significantly increased by 17.6+/-1.1% after 6 h. The present study indicated that the secondary increase in the volume of the scala media following glycerol intake played an important role in the rebound phenomenon in the glycerol test, although the mechanism underlying the hearing loss with the endolymphatic hydrops remains to be elucidated.

Administration, Oral↗
PubMed1999

Selection of intracellularly active ribozymes in mammalian cells.

Ribozymes are expected to be useful as antiviral agents and powerful tools of functional analysis of unknown gene products in vivo. For use of ribozymes in vivo, they must be fully functional in the intracellular environment. Not all ribozymes selected in vitro would be expected to work in vivo, whereas ribozymes selected in the intracellular environment should retain their function in vivo. With the eventual aim of using ribozymes as antiviral agents or biological tools in mammalian cells, we then devised a novel selection system in mammalian cells of active ribozymes by targeting at a gene for the cyclin dependent kinase inhibitor (CDKI), p16INK4a. In this system, we found that p16INK4a-knockdown cells became malignant and they formed foci. In the mammalian system, we confirmed that the selected cells harbored the active ribozyme, indicating that our positive selection systems in vivo were operational.

3T3 Cells↗
PubMed1999

Clinical implications of circulating soluble Fas and Fas ligand in patients with acute myocardial infarction.

BACKGROUND: Apoptotic cell death is the major form of myocardial damage produced by coronary ischemic events. OBJECTIVE: To assess whether circulating levels of soluble Fas (sFas), an inhibitor of apoptosis, and sFas ligand, an inducer of apoptosis, in patients with coronary artery disease are greater than normal. METHODS: Forty-seven patients [acute myocardial infarction (AMI) in 17, old myocardial infarction (OMI) in 15, stable angina in 15] and 10 normal control subjects participated in this study. Serum levels of sFas and sFas ligand in all patients were measured, and cardiac catheterizations were performed. RESULTS: Serum levels of sFas were greater than normal only in patients with AMI (4.6 +/- 1.6 ng/ml); the levels were significantly higher than those in patients with OMI (2.1 +/- 0.6 ng/ml) and stable angina (2.2 +/- 0.5 ng/ml), and in normal subjects (2.0 +/- 0.6 ng/ml; P < 0.0001). However, there was no difference among serum levels of sFas ligand for all groups. For patients with AMI, there was no significant correlation between serum levels of sFas and peak levels both of plasma creatine phosphokinase and of plasma myosin light chain type I as clinical indexes of infarct size. However, there were significant correlations between serum levels of sFas and both pulmonary artery wedge pressure (r = 0.767, P = 0.0003) and left ventricular end-diastolic pressure (r = 0.629, P = 0.03). CONCLUSIONS: Circulating sFas increases in concentration in relation to the severity of hemodynamic conditions in patients with AMI, but it is independent from size of infarct. Therefore, circulating sFas could play an important role as the marker of pathophysiologic conditions associated with cardiomyocyte apoptosis in AMI.

Aged↗
PubMed1999

Futalosine and its derivatives, new nucleoside analogs.

Futalosine, a new nucleoside analog, was isolated from a fermentation broth of Streptomyces sp. MK359-NF1. Some chemical derivatives of futalosine were prepared. 6-O-Methylfutalosine methylester inhibited growth of HeLa-S3 cells in vitro (IC50 = 19.5 micrograms/ml) in contrast to the weak activity of futalosine. 6-O-Methylfutalosine methylester at concentrations higher than 10 micrograms/ml inhibited incorporation of 3H-TdR and 3H-UR but not 3H-Leu in the acid-soluble fractions of HeLa-S3 cells.

Antibiotics, Antineoplastic↗
PubMed1999

Left ventricular end-systolic wall stress is a potent prognostic variable in patients with dilated cardiomyopathy.

Dilated cardiomyopathy is an important cause of morbidity and mortality among patients with heart failure. Left ventricular dilation is viewed as a compensatory response to maintain stroke volume, and left ventricular dilation is directly related to the increase of wall stress. However, only a few studies have examined whether wall stress can be a prognostic variable in patients with dilated cardiomyopathy. This study was designed to elucidate whether left ventricular systolic wall stress was related to the prognosis in patients with dilated cardiomyopathy. Twenty-five normal control subjects and 68 patients with dilated cardiomyopathy participated in this study. Hemodynamic parameters and left ventricular systolic wall stress were determined using echocardiography. In addition, the extent score determined by thallium-201 myocardial scintigraphy was measured as an index of cumulative loss of myocardium. During the 53-month follow-up period, 13 patients died of cardiac events. In a stepwise multivariable analysis, end-systolic wall stress and fractional shortening were significant predictors of survival. The extent score was markedly greater in the patients who died than in alive patients. There was a significant correlation between end-systolic wall stress and extent score (r=0.501, p=0.0001). Left ventricular end-systolic wall stress is an important predictor of mortality in patients with dilated cardiomyopathy.

Adult↗