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Biomedical subjects

T Iwamoto

Publications and source records attributed to T Iwamoto.

At least 109 records · Page 6Linked to original sources
PubMed2000

[Factors influencing platelet function in elderly patients with chronic phase thrombotic diseases].

To clarify the factors influencing platelet function in elderly patients with chronic thrombotic disease, platelet aggregability was studied in 839 blood samples from 497 patients with a variety of diseases. Clinical stage (thrombotic disease), vascular risk factors, and data concerning any administration of antiplatelet drugs were assessed, as well as brain computerized tomographic and carotid ultrasonographic findings. Platelet aggregability was determined spectrophotometrically with an aggregometer (PAM-8T) and adenosine-5'-diphosphate as an agonist to determine new parameters: the grading curve (GC) type, and platelet aggregability threshold index (PATI). Multiple regression analysis showed that the antiplatelet therapy greatly influenced the GC type. Platelet aggregability, which accelerated with aging, was strongly suppressed by ticlopidine. Furthermore, excluding samples with antiplatelet therapy, statistical analysis showed that platelet aggregability was accelerated in women, and in patients with bilateral or complicated carotid lesions, although these patients were significantly older than the others. These findings suggested that accelerated aggregability in the elderly substantially reflected the progress of arteriosclerosis with age. Moreover, the findings indicated that the determination of GC type and PATI were useful in monitoring elderly patients receiving antiplatelet therapy, especially with ticlopidine.

Aged↗
PubMed2000

[Hemodynamics of the lower extremities in patients with decubitus ulcers using the ultrasonic Doppler method].

Our clinical experience indicates that decubitus ulcers with tissue loss/necrosis extending beyond the subcutaneous fat in aged patients are liable to become refractory and that most of these patients experience a cold feeling/cyanosis in the lower extremities. In order to determine the relationship between the severity of the decubitus ulcers and the hemodynamics in the lower extremities, we conducted a blood flow test using the ultrasonic Doppler method on the lower extremities in patients. Sixty-eight inpatients (38 men, 30 women, with an average age of 80.5 +/- 7.6 years old) were selected. B-mode tomographs were obtained with an ultrasonic diagnostic apparatus. The power Doppler method was used to measure blood flow rate, vascular lumen diameter, and intravascular blood flow at the dorsalis pedis artery, posterior tibial artery, peroneal artery furcation, and femoral artery. The subjects were divided into three groups: patients without decubitus ulcers; patients with mild to moderate decubitus ulcers of IAET Classification grade I-III; and patients with severe decubitus ulcers (IAET Classification grade IV), and the measurements were compared among the groups. The results revealed a tendency for the vascular lumen to become narrowed and intravascular blood flow to be reduced at all sites as decubitus ulcers increased in severity and showed the hemodynamics in the lower extremities to be particularly poor in the severe group. We measured the hemodynamics in the lower extremity with the ultrasonic Doppler method from the viewpoint of decubitus ulcer prevention and found differences in blood flow in the lower extremities according to the severity of decubitus ulcers. A reduction in blood flow in the lower extremities is considered to indirectly indicate a susceptibility to decubitus ulcers and to serve as a sign of its exacerbation. We consequently considered the test to be useful and concluded that deterioration of hemodynamics due to the progress of arteriosclerosis is one of the causes of decubitus ulcer exacerbation.

Aged↗
PubMed2000

[Clinical findings of arteriosclerosis and serum lipoprotein(a) concentration in elderly patients].

This study was conducted to evaluate the relationship between arteriosclerosis and lipoprotein(a) [Lp(a)] from the point of view of aging. A total of 354 patients (167 men) aged 60 or more were enrolled and serum Lp(a) levels, vascular risks, and complications were studied. Patients were divided into 3 groups according to age: group I (n = 73: aged 60 to 69), group II (n = 144: aged 70-79), and group III (n = 137: aged 80 or more). Vascular complications were assessed by carotid ultrasonography (US), ECG, and ankle pressure index (API), US findings were stratified according to the distribution of plaque lesions in unilateral and bilateral lesions, while plaque types were subdivided based on the morphology and US echogenicity. Male patients with risk factors (diabetes, hypercholesterolemia, cigarette smoking) as well as stroke were frequent in group I, indicating some selection bias. However, there was no difference in Lp(a) level among the three groups. Carotid lesions, especially bilateral lesions with more thickened plaques, and low API were both significantly frequent in group III. Logistic regression analysis showed that carotid lesions were influenced not only by aging, but also independently by high Lp(a) levels in group III, and by hypertension in group II. A high Lp(a) level was related to hypercholesterolemia and hypoechoic plaque. These findings indicated that atherosclerosis, which developed in both the carotid and peripheral arteries with aging, was related to different risks in each decade of life. Furthermore, it seems that a long period of high Lp(a) levels may promote the formation of hypoechoic plaque.

Activities of Daily Living↗
PubMed2000

[Relation between hippocampal damage and cerebral cortical function in Alzheimer's disease].

We investigated the relation between hippocampal damage and cerebral cortical dysfunction in Alzheimer's disease (AD) using MRI and SPECT. Nineteen patients with AD and 10 control subjects were studied. Hippocampal damage (including hippocampal formation, entorhinal cortex, and parahippocampal white matter) was assessed to evaluate the severity of atrophy and the magnetization transfer ratio (MTR) and cerebral cortical dysfunction was evaluated by quantitative cerebral blood flow (CBF) measurements using SPECT with 99mTc-ECD. Compared with controls, patients with AD had significantly more atrophy of the medial temporal lobe and a decrease in MTRs of the hippocampus and parahippocampus. There were significant correlations between the severity of hippocampal damage and regional CBF in temporoparietal lobes. Mini-Mental State Examination scores significantly correlated with the severity of hippocampal damage and regional CBFs in temporoparietal lobes. These results suggest that the functional effect of hippocampal damage occurs in temporoparietal lobes in AD, probably due to neuronal disconnections between hippocampal areas (including the entorhinal cortex) and temporoparietal lobes.

Aged↗
PubMed2000

Inhibition of low-density lipoprotein oxidation by astaxanthin.

Marine animals produce astaxanthin which is a carotenoid and antioxidant. In this study we determined the in vitro and ex vivo effects of astaxanthin on LDL oxidation. The oxidation of LDL was measured in a 1 ml reaction system consisting of increasing concentrations of astaxanthin (12.5, 25.0, 50.0 microg/ml), 400 microM V-70 (2, 2'-azobis(4-methoxy-2, 4-dimethylvaleronitrile)), and LDL (70 microg/ml protein). Astaxanthin dose, dependently significantly prolonged the oxidation lag time (31.5, 45.4, 65.0 min) compared with the control (19.9 min). For the ex vivo study 24 volunteers (mean age 28.2 [SD 7.8] years) consumed astaxanthin at doses of 1.8, 3.6,14.4 and 21.6 mg per day for 14 days. No other changes were made in the diet. Fasting venous blood samples were taken at days 0, +14. LDL lag time was longer (5.0, 26.2, 42.3 and 30.7% respectively) compared with day 0 after consuming astaxanthin at doses of 1.8, 3.6,14.4 and 21.6 mg for 14 days compared with day 0, but there was no difference in oxidation of LDL between day 0 (lag time 59.9+/-7.2 min) and day 14 (57.2+/-6.0 min) in the control group. Our results provide evidence that consumption of marine animals producing astaxanthin inhibits LDL oxidation and possibly therefore contributes to the prevention of atherosclerosis.

Adult↗
PubMed2000

FR901469, a novel antifungal antibiotic from an unidentified fungus No.11243. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological properties.

FR901469 is a novel antifungal antibiotic produced by an unidentified fungus No.11243. This compound was isolated from the culture broth by solvent extraction, HP-20 and YMC ODS gel column chromatography, and lyophilization. FR901469 is a white powder which melts at 182 approximately 187 degrees C and possesses the molecular formula C71H116N14O23. This compound has good water solubility. FR901469 inhibited the activity of 1,3-beta-glucan synthase from Candida albicans with an IC50 value of 0.05 microg/ml, and displayed greater inhibitory activity than other 1,3-beta-glucan synthase inhibitors such as, WF11899A, echinocandin B, aculeacin A, and papulacandin B.

Animals↗
PubMed2000

FR901469, a novel antifungal antibiotic from an unidentified fungus No.11243. II. In vitro and in vivo activities.

FR901469 is a water-soluble macrocyclic lipopeptidolactone (C71H116N14O23) that has inhibitory activity against 1,3-beta-glucan synthase and exhibits in vitro and in vivo antifungal activity against both Candida albicans and Aspergillus fumigatus. The MICs of FR901469 against Candida albicans FP633 and Aspergillus fumigatus FP1305 in a micro-broth dilution test were 0.63 and 0.16 microg/ml, respectively. FR901469 showed excellent efficacy by subcutaneous injection against both Candida albicans and Aspergillus fumigatus in a murine systemic infection mode, with ED50s of 0.32 and 0.2 mg/kg, respectively. This compound also showed potent anti-Pneumocystis activity in the nude mice model with experimental Pneumocystis pneumonia. The hemolytic activity of FR901469 towards mouse red blood cells, is about 30-fold weaker than that of amphotericin B.

Animals↗
PubMed2000

[Clinical study of transurethral surgery for benign prostatic hyperplasia using a thick loop (VaporTome)].

From December 1996 to June 1998, we performed transurethral surgery of the prostate using a thick loop, VaporTome developed by Circon ACMI on 23 patients with symptomatic benign prostatic hyperplasia (BPH). The mean international prostate symptom score decreased significantly, from 22.6 at baseline to 9.0, 6.5, 4.9 and 5.3 at 1, 3, 6 and 12 months after operation, respectively. The mean quality of life index also decreased significantly, from 5.5 to 1.8, 1.8, 1.4 and 1.2, respectively. The mean peak flow rate increased significantly, from 6.2 preoperatively to 15.8, 17.1, 16.6 and 17.4 ml/sec at 1, 3, 6 and 12 months after operation, respectively. The mean prostate volume decreased significantly, from 66.9 to 24.8, 17.3, 19.0 and 18.2 ml. The mean residual urine decreased significantly, from 167.9 to 11.4, 9.4, 12.8 and 20.4 ml. As for overall efficacy, the rate of excellent and good cases at 1, 3, 6 and 12 months was 80.9, 89.4, 94.7 and 85.8%, respectively. No serious complications were observed. Our clinical results suggest that transurethral surgery for BPH using VaporTome has several potential advantages including high efficacy, minimal morbidity compared with standard transurethral resection of the prostate and lower cost compared with other minimally invasive procedures.

Aged↗
PubMed2000

[A case of recurrent spontaneous vesical rupture subsequent to irradiation for uterine cancer].

The patient, a 68-year-old woman, had undergone radical hysterectomy and post-operative radiotherapy for uterine cancer in 1974. She was admitted to our hospital complaining of abdominal pain in February, 1996. Contrast-enhanced computed tomographic scan and cystography showed leakage of contrast medium around the bladder. We diagnosed her with spontaneous vesical rupture, and performed conservative therapy. Two months later, she was re-admitted with recurrent vesical rupture. We again performed conservative therapy. We consider that conservative therapy can be indicated for spontaneous vesical rupture with good general condition and no severe urinary tract infection.

Aged↗
PubMed2000

Magnetization transfer measurements of the hippocampus in patients with Alzheimer's disease, vascular dementia, and other types of dementia.

BACKGROUND AND PURPOSE: Although atrophy of structures in the medial temporal lobe has been considered an indication of Alzheimer's disease (AD), atrophic changes on MR images have also been associated with other dementing diseases and are not specific to AD. This study was undertaken to determine whether characteristic alterations in the hippocampus of patients with AD are detectable with magnetization transfer (MT) imaging. METHODS: Coronal MT imaging was performed in 35 patients with probable AD, in 14 patients with vascular dementia, in 13 patients with other types of dementia, and in 23 control subjects to measure MT ratios of the hippocampus. Medial temporal lobe atrophy was graded subjectively on a five-point scale. RESULTS: Scores of medial temporal lobe atrophy in all dementia groups were significantly higher than those in control subjects, but no differences were found among the dementia groups. MT ratios in the hippocampus were significantly lower in patients with AD than in those with non-AD dementia and in the control subjects; however, no differences were found between the non-AD dementia patients and the control subjects. MT ratio measurements were better than visual analysis of atrophy for differentiating AD patients from those with non-AD dementia (an overall discrimination rate of 77% versus 65%). MT ratios significantly correlated with scores on the Mini-Mental State Examination and with medial temporal lobe atrophy in AD patients but not in patients with non-AD dementia. CONCLUSION: MT measurements may be more specific than visual analysis in detecting structural damage of the hippocampus in AD patients and might be useful in discriminating AD from vascular dementia and other types of dementia.

Aged↗
PubMed2000

[Recent trends in male reproductive disorders].

There is growing concern about the considerable decline in semen quality and the increase of male reproductive disorders such as testicular cancer, hypospadias and cryptorchidism over the past decades. Such trend has also been manifested itself in the form of increasing demand for assisted reproductive technology in recent year. Concerning the above Skakkebaek has been proposed a hypothesis that there may exist common etiological factors for these male reproductive disorders. He presented a new evidence that male reproductive disorders are symptoms of an underlying testicular dysgenesis syndrome at the workshop "Hormones and Endocrine Disruptors in Good and Water: Possible Impact on Human Health" held in Copenhagen, May 27-30, 2000. In this paper, we review several topics presented in this workshop.

Cryptorchidism↗
PubMed2000

[A case of idiopathic tracheal stenosis].

A 44-year-old woman who had been treated for bronchial asthma for 5 years was admitted for further evaluation of progressive dyspnea. Physical examination revealed wheezing originating in the neck. A flow-volume curve suggested upper-airway stenosis. The patient had no history of trauma, endotracheal intubation, granulomatous diseases, or any other severe respiratory tract infections. Chest radiography and laboratory examination showed no abnormalities. Tracheal X-P, computed tomography and magnetic resonance imaging of the neck, and bronchoscopy demonstrated circumferential subglottic tracheal stenosis extending for 40 mm. The diameter of the lumen was 5 mm at its narrowest. The trachea distal to the lesion was normal. Bronchoscopic biopsy revealed thickened tracheal mucosa and submucosa with increased fibrous tissue and chronic inflammatory cell infiltration, suggesting a nonspecific inflammatory process. These findings are compatible with idiopathic tracheal stenosis, which was reported by Bhalla et al. The patient was treated with Nd-YAG laser surgery via a fiberoptic bronchoscope, which resulted in a great improvement in respiration. Regression of the lesion has not occurred in the 40 months since the laser surgery. The majority of patients with this condition have been treated by surgical resection of the stenotic lesion and reconstruction. However, the success of Nd-YAG laser surgery in the present case suggests that this approach would be a satisfactory alternative procedure for treatment of idiopathic tracheal stenosis.

Bronchoscopy↗
PubMed1999

High permissivity of the fish cell line SSN-1 for piscine nodaviruses.

Seventeen isolates of piscine nodavirus from larvae or juveniles of 13 marine fish species affected with viral nervous necrosis (VNN) were examined for their infectivity to a fish cell line SSN-1. Based on cytopathic effects (CPE) and virus antigen detection by fluorescent antibody technique (FAT) after incubation at 25 degrees C, the infectivity of these virus isolates was divided into 4 groups. Group 1, including 9 virus isolates from 4 species of grouper, 2 species of sea bass, barramundi, rock porgy, and Japanese flounder showed CPE characterized by rounded, granular cells with heavy cytoplasmic vacuoles within 3 d post-incubation (p.i.), and the monolayer partially or completely disintegrated over 3 to 6 d p.i. Scattered FAT-positive cells appeared at 3 h p.i. and spread through the cell sheet with an increasing fluorescence signal over 24 h p.i. Group 2, consisting of 3 virus isolates from striped jack, induced CPE with thin or rounded, granular, refractile cells without conspicuous vacuole formation, and extensive FAT-positive reaction was observed in a time course similar to that of Group 1. Cells inoculated with Group 3 (1 isolate from tiger puffer) developed no distinct CPE but viral infection was evidenced by localized FAT-positive cells. There were no FAT-positive cells in Group 4, which included 4 isolates from Japanese flounder, Pacific cod and Atlantic halibut. However, when incubation was performed at 20 degrees C, the SSN-1 cells inoculated with the Group 3 isolate showed CPE similar to that of Group 1 and extensive FAT-positive reaction. Evidence of virus proliferation at 20 degrees C was also obtained in Group 4 isolates. The virus titers in the infected fish varied from 10(11) to 10(16) tissue culture infectious dose (TCID50) g(-1) of fish. There is a good correlation between these infectivities to the SSN-1 cells and the coat protein gene genotypes of the isolates. The present results indicate that SSN-1 cells are useful for propagating and differentiating genotypic variants of piscine nodavirus.

Animals↗
PubMed1999

Spectroscopic characterization of carbon monoxide complexes generated for copper/topa quinone-containing amine oxidases.

Carbon monoxide complexes have been generated for copper/topa quinone (TPQ)-containing amine oxidases from Arthrobactor globiformis (AGAO) and Aspergillus niger (AO-I) and characterized by various spectroscopic measurements. Addition of CO to AGAO anaerobically reduced with its substrate 2-phenylethylamine led to a slight increase of absorption bands at 440 and 470 nm derived from the semiquinone form (TPQ(sq)) of the TPQ cofactor, concomitantly giving rise to new CO-related absorption bands at 334 and 434 nm. The intensity of the TPQ(sq) radical EPR signal at g = 2.004 also increased in the presence of CO, while its hyperfine coupling structure was affected insignificantly. FT-IR measurements revealed C-O stretching bands (nu(CO)) at 2063 and 2079 cm(-1) for the CO complex of the substrate-reduced AGAO (at 2085 cm(-1) for AO-I), which shifted nearly 100 cm(-1) to lower frequencies upon using (13)C(18)O. Collectively, these results suggest that CO is bound to the Cu(I) ion in the Cu(I)/TPQ(sq) species formed in the reductive half-reaction of amine oxidation, thereby shifting the Cu(II)/aminoresorcinol right arrow over left arrow Cu(I)/semiquinone equilibrium toward the latter. When AGAO was reduced with dithionite, an intermediary form of the enzyme with Cu(II) reduced to Cu(I) but TPQ still in the oxidized state (TPQ(ox)) was produced. Dithionite reduction of AGAO in the presence of CO resulted in the immediate formation of FT-IR bands at 2064 and 2083 cm(-1), which were assigned to the nu(CO) bands of the CO bound to the TPQ(ox) enzyme. The intense 2083 cm(-1) band was then displaced by a new band at 2077 cm(-1), corresponding to the formation of the fully reduced topa. Significant variation of these nu(CO) frequencies indicates that vibrational properties of CO bound to copper amine oxidases are sensitively influenced by the coordination structure of the Cu(I) ion, which may be modulated by the chemical and redox states of the TPQ cofactor.

Amine Oxidase (Copper-Containing)↗
PubMed1999

Chimeric analysis of Na(+)/Ca(2+) exchangers NCX1 and NCX3 reveals structural domains important for differential sensitivity to external Ni(2+) or Li(+).

Externally applied Ni(2+), which apparently competes with Ca(2+) in all three isoforms of Na(+)/Ca(2+) exchanger, inhibits exchange activity of NCX1 or NCX2 with a 10-fold higher affinity than that of NCX3, whereas stimulation of exchange by external Li(+) is significantly greater in NCX2 and NCX3 than in NCX1 (Iwamoto, T., and Shigekawa, M. (1998) Am. J. Physiol. 275, C423-C430). Here we identified structural domains in the exchanger that confer differential sensitivity to Ni(2+) or Li(+) by measuring intracellular Na(+)-dependent (45)Ca(2+) uptake in CCL39 cells stably expressing NCX1/NCX3 chimeras or mutants. We found that two segments in the exchanger corresponding mostly to the internal alpha-1 and alpha-2 repeats are individually responsible for the alteration of Ni(2+) sensitivity, both together accounting for approximately 80% of the difference between NCX1 and NCX3. In contrast, the segment corresponding to the alpha-2 repeat fully accounts for the differential Li(+) sensitivity between the isoforms. The Ni(2+) sensitivity was mimicked, respectively, by simultaneous substitution of two amino acids in the alpha-1 repeat (N125G/T127I in NCX1 and G159N/I161T in NCX3) and substitution of one amino acid in the alpha-2 repeat (V820A in NCX1 and A809V in NCX3). On the other hand, the Li(+) sensitivity was mimicked by double substitution mutation in the alpha-2 repeat (V820A/Q826V in NCX1 and A809V/V815Q in NCX3). Single substitution mutations at Asn(125) and Val(820) of NCX1 caused significant alterations in the interactions of the exchanger with Ca(2+) and Ni(2+), and Ni(2+) and Li(+), respectively, although the extent of alteration varied depending on the nature of side chains of substituted residues. Since the above four important residues are mostly in the putative loops of the alpha repeats, these regions might form an ion interaction domain in the exchanger.

Amino Acid Sequence↗
PubMed1999

Diffusion-weighted and magnetization transfer imaging of the corpus callosum in Alzheimer's disease.

We investigated structural changes of the corpus callosum in patients with Alzheimer's disease (AD) using sagittal diffusion-weighted (DW) and magnetization transfer (MT) imaging. Patients with AD (n=23) had a significantly decreased area only in the posterior portion of the corpus callosum. Apparent diffusion coefficient (ADC) values perpendicular to the commisural fiber orientation were significantly higher in the anterior portion of the corpus callosum without definite atrophy, as well as in the posterior portion with significant atrophy, in patients with AD than in controls (n=16) and thus diffusion in these regions showed a significantly lower degree of anisotropy in patients than in controls. MT ratios were also significantly lower in patients with AD in the anterior and posterior portions of the corpus callosum than in controls. These findings probably reflect structural changes in the corpus callosum including axonal loss and/or demyelination. DW and MT imagings may be useful in detecting degeneration of the corpus callosum in AD.

Aged↗
PubMed1999

Magnetization transfer ratio in cerebral white matter lesions of Binswanger's disease.

We measured the magnetization transfer (MT) ratios in white matter lesions of Binswanger's disease (BD) and compared them with BD and with similar-appearing changes in non-demented elderly subjects and cerebral infarction. Four subject groups were studied: 30 patients with BD and periventricular hyperintensity (PVH) on MRI, 29 patients with ischemic cerebrovascular event with PVH but no dementia, 17 patients with old cerebral infarction, and 26 elderly control subjects. MT ratios were calculated for areas of PVH in BD and non-demented subjects, of infarction, and of normal-appearing white matter in controls. The decrease in MT ratios for areas in PVH of non-demented subjects and BD and in infarction compared with normal white matter in controls was 12, 20, and 35%, respectively. The MT ratio in PVH of BD was significantly lower than that in PVH of non-demented subjects, but not to the levels seen in areas of infarction. There was a significant high correlation between the Mini-Mental State Examination score and MT ratio for area of PVH (r = 0.790). MT ratio distinguishes PVH in BD patients from those in non-demented subjects, suggesting underlying histopathological differences. Tissue damage in white matter lesions of BD may be more severe than that in non-demented subjects, but not as much as with complete infarction.

Aged↗