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S Sakamoto

Publications and source records attributed to S Sakamoto.

At least 199 records · Page 11Linked to original sources
PubMed1998

[Pitfalls and their solution in MIDCAB].

Between July 1996 and September 1997, 11 patients underwent coronary artery bypass starting with left anterior small thoracotomy. All patients were evaluated with Electron Beam Computed Tomography (EBCT) preoperatively. Two patients out of 11 required conversion to sternotomy due to inadequate length of left internal mammary artery (LIMA) graft. One patient had a graft occlusion and underwent reoperation, when a graft avulsion was identified. Distance between LIMA and LAD by EBCT highly predicted needs of procedure modification to obtain additional length of graft. We demonstrated anterior pericardiopexy as an additional technique for protecting LIMA graft from abnormal tension. We conclude that it is crucial to harvest adequate length of LIMA in MIDCAB and anterior pericardiopexy may be useful to prevent a graft avulsion.

Aged↗
PubMed1998

How to lower perinatal mortality? Perinatal care in Japan.

OBJECTIVE: To review the 30-year history of perinatal medical care in Japan, and the recently initiated regionalization system of perinatal centers, new technologies and treatments in obstetric and neonatal medicine developed in Japan. STATISTICAL DATA: Maternal and neonatal health statistics of Japan released by the Ministry of Health and Welfare, Japanese Society of Obstetrics and Gynecology, Japanese Pediatric Society, and Tokyo Women's Medical University. LABORATORY DATA: Serological assay and immunohistochemical staining employing TKH-2 antibody for the diagnosis of amniotic fluid embolism, and assaying granulocyte elastase as a specific inflammatory marker in mucous samples from the uterine cervical canal for the prediction of preterm labor or premature rupture of membranes. TREATMENTS: Urinary trypsin inhibitor (Urinastatin) for the prevention of preterm delivery, and a double-blind, placebo-controlled, randomized trial of antithrombin-III therapy in severe preeclampsia. CONCLUSION: Over the last 30 years, the statistical data of perinatal health care, such as maternal and perinatal mortality rates, have markedly improved in Japan. These results are supported by the advanced technologies and newly developed treatments in obstetric and neonatal medicine. The regionalization of perinatal centers, a national project in order to assure a systematic collaboration among primary, secondary, and tertiary centers, has just started in Japan. It also aims at systematization of the function of perinatal centers on the national level through the informative promoting action.

Female↗
PubMed1998

[Mitral valve tissue characterization using acoustic microscopy].

Mitral valve hardness in the rough and clear zones was evaluated by measuring the propagation velocity (m/sec) of ultrasound through the valve, based on the hypothesis that harder tissues will have larger ultrasonic velocity values passing through the tissue. Mitral valve specimens were obtained from 16 normal subjects (age, 15-72 years) at autopsy. An acoustic microscope, operating at 450 MHz, was used to measure the ultrasonic velocity through the three layers of the valve: the atrialis; the spongiosa; and the fibrosa. Furthermore, the mean ultrasonic velocity through the three layers was measured. These measurements were conducted in the rough and clear zones of the valve. In the rough zone, the ultrasonic velocities were 1,634 +/- 71 in the atrialis, 1,574 +/- 37 in the spongiosa, and 1,726 +/- 97 m/sec in the fibrosa. In the clear zone, the ultrasonic velocities were 1,691 +/- 117 in the atrialis, 1,575 +/- 44 in the spongiosa, and 1,909 +/- 131 m/sec in the fibrosa. There were significant differences between velocities in the three layers in both the rough and clear zones. Furthermore, the mean ultrasonic velocity in the three layers in the clear zone (1,887 +/- 138 m/sec) was higher than that in the rough zone (1,642 +/- 53 m/sec; p < 0.001). These findings show that fibrosa, which is rich in collagen fibers, is harder than atrialis, which is rich in elastic fibers, and the spongiosa, which is poor in connective tissues, is the softest. The higher mean ultrasonic velocity in the clear zone than in the rough zone indicates that the clear zone is harder than the rough zone, although the clear zone is thinner than the rough zone.

Adolescent↗
PubMed1998

Cerebral glucose metabolism in patients with frontotemporal dementia.

UNLABELLED: Frontotemporal dementia (FTD) is a dementia syndrome characterized by peculiar behavioral changes arising from frontotemporal involvement and distinct from Alzheimer's disease (AD). The purpose of this study was to elucidate the specific patterns in cerebral glucose metabolism in patients with FTD and to compare them with the patterns in patients with AD and normal elderly subjects using fluorodeoxyglucose (FDG) and PET. METHODS: Twenty-one patients with a clinical diagnosis of FTD [mean age 67.0 +/- 7.0 yr, Mini Mental State Examination (MMSE) score 18.7 +/- 5.7], 21 age-, sex- and dementia-severity-matched patients with probable AD (mean age 66.9 +/- 7.1 yr, MMSE score 20.2 +/- 5.5) and 21 age- and sex-matched normal control subjects (mean age 66.8 +/- 5.7 yr) were studied. The cerebral metabolic rate for glucose (CMRglc) was measured with FDG and PET. Absolute measures of regional CMRglc were compared among the three groups. One-way ANOVA and the posthoc Tukey HSD test were used for statistical analyses. RESULTS: In the FTD group, CMRglc was preserved only in the left cerebellum, right sensorimotor area and occipital lobes. The CMRglc was significantly lower in the FTD group as opposed to the AD group in the hippocampi, orbital gyri, anterior temporal lobes, anterior cingulate gyri, basal ganglia, thalami, middle and superior frontal gyri and left inferior frontal gyrus. CONCLUSION: Although metabolic abnormality in FTD is predominant in the frontal and anterior temporal lobes and the subcortical structures, it is more widespread than has been previously stressed. These findings document an FTD-specific cerebral involvement and facilitate differential diagnosis of degenerative dementias.

Aged↗
PubMed1997

Mutational analysis of putative SCH 28080 binding sites of the gastric H+,K+-ATPase.

A compound, SCH 28080 (2-methyl-8-(phenylmethoxy)imidazo [1,2-a]pyridine-3-acetonitrile), reversibly inhibits gastric and renal ouabain-insensitive H+,K+-ATPase, but not colonic ouabain-sensitive H+,K+-ATPase. By using the functional expression system and site-directed mutagenesis, we analyzed the putative binding sites of SCH 28080 in gastric H+,K+-ATPase alpha-subunit. It was previously reported that the binding site of SCH 28080, which is a K+-site inhibitor specific for gastric H+,K+-ATPase, was in the first extracellular loop between the first and second transmembrane segments of the alpha-subunit; Phe-126 and Asp-138 were putative binding sites. However, we found that all the mutants in the first extracellular loop including Phe-126 and Asp-138 retained H+, K+-ATPase activity and sensitivity to SCH 28080. Therefore, amino acid residues in the first extracellular loop are not directly involved in the SCH 28080 binding nor indispensable for the H+, K+-ATPase activity. Here we propose a candidate residue that is important for the binding with SCH 28080, Glu-822 in the sixth transmembrane segment. Mutations of Glu-822 to Asp and Ala (mutants termed E822D and E822A, respectively) decreased the ATPase activity to about 45% and 35% of the wild-type enzyme, respectively, while the mutations to Gln and Leu abolished the activity. Mutant E822A showed a significantly lower affinity for K+ than the wild-type enzyme, indicating that Glu-822 is involved in determining the affinity for K+. The sensitivity of mutant E822D to SCH 28080 was 8 times lower than that of the wild-type enzyme. The counterpart of Glu-822 in gastric H+,K+-ATPase is Asp in Na+,K+-ATPase and other colonic ouabain-sensitive H+,K+-ATPase, which are insensitive to SCH 28080. These results suggest that Glu-822 is one of important sites that bind with SCH 28080.

Adenosine Triphosphate↗
PubMed1997

8-(1H-imidazol-1-yl)-7-nitro-4(5H)-imidazo[1,2-alpha]quinoxalinone and related compounds: synthesis and structure-activity relationships for the AMPA-type non-NMDA receptor.

As a part of our program to discover novel antagonists for the AMPA subtype of EAA receptors, we designed and synthesized a series of heterocyclic-fused imidazolylquinoxalinones 5a-c, 9, 11, 14a-e, and 18 which led from 6-(1H-imidazol-1-yl)-7-nitro-2,3(1H,4H)-quinoxalinedione hydrochloride (1a.HCl, YM90K) by replacement of its amide with the imidazole and triazole rings. Their activity was evaluated by inhibiting [3H]AMPA binding from rat whole brain. As a result, it appeared that 8-(1H-imidazol-1-yl)-7-nitro-4(5H)-imidazo[1,2-alpha]quinoxalinone (5a) and its [1,2,4]triazolo[4,3-alpha] analogue 14a possessed high affinity for AMPA receptors with Ki values of 0.057 and 0.19 microM, respectively, similar to the activity of 1a and NBQX (2) (1a, Ki = 0.084 microM; 2, Ki = 0.060 microM). In contrast, 8-(1H-imidazol-1-yl)-7-nitro-4(5H)-imidazo[1,5-alpha]quinoxalinone (5b) and 7-(1H-imidazol-1-yl)-8-nitro-4(5H)-[1,2,4]triazolo[4,3-alpha]quinoxalino ne (18) showed no or weak affinity for the receptors. Hence, we deduced that the nitrogen atom of the fused heterocycles at the 3-position of 5a and 14a plays an essential role as hydrogen bond acceptors in binding to AMPA receptors, whereas their amides act as proton donors. From the SAR on 1-alkyl derivatives of 5a and 14a, it was indicated that introduction of suitable 1-alkyl substituents led to a severalfold improved AMPA affinity. A computational study on a model of water-quinoxaline complexes, a mimic of the putative hydrogen-bonding interaction between the receptors and quinoxalines, indicated that the different affinities of 5a, 14a, 1a, and 19 for the AMPA receptor may depend on, at least in part, each stabilization energy for the interaction. On this basis, we propose a pharmacophore model of AMPA receptors for the binding of the imidazolylquinoxaline derivatives. The heterocyclic-fused quinoxalinones 5a,c and 9 showed potent inhibitory activity in KA-induced toxicity for hippocampal cell culture with IC50 values of 0.30, 0.32, and 0.30 microM, respectively (1a, 0.81 microM; 2, 0.38 microM). Moreover 5a possesses over 5000-fold AMPA selectivity against both the NMDA receptor and the glycine site on the NMDA receptor.

Animals↗
PubMed1997

Demonstration of decreased posterior cingulate perfusion in mild Alzheimer's disease by means of H215O positron emission tomography.

Although decreased posterior cingulate metabolism in Alzheimer's disease (AD) has been previously reported, there have been no reports on posterior cingulate perfusion. In this study we evaluated posterior cingulate perfusion as a relative value using statistical parametric maps (SPMs) and as an absolute value using conventional region of interest (ROI) settings. Twenty-eight subjects, including 14 patients with mild AD (mean age: 66.4+/-12.1 years) and 14 normal controls (65.9+/-7.3 years) were studied. Regional cerebral blood flow (CBF) was measured with H215O and positron emission tomography (PET). In the SPM analysis, the left posterior cingulate and left parietotemporal CBFs were significantly decreased in the patients with mild AD (P<0.001). At a lower statistical threshold (P<0.05), the right posterior cingulate and right parietotemporal CBFs were also significantly decreased in the AD patients. In the ROI studies, the left parietal and posterior cingulate CBFs in the patients with mild AD were significantly lower than those of the normal controls by analysis of variance and post-hoc Scheffé's test (P<0.001). We conclude that posterior cingulate perfusion is decreased in mild AD, reflecting the pathological changes and metabolic reduction in the posterior cingulate gyrus that have previously been reported to occur in mild AD.

Aged↗
PubMed1997

Regional cerebral blood flow and oxygen metabolism in a patient with Korsakoff syndrome.

We report a functional neuroimaging study of a patient clinically diagnosed with Korsakoff syndrome. Positron emission tomography (PET) with the 15O inhalation method showed decreased regional cerebral blood flow (rCBF) and decreased regional cerebral metabolic ratio for oxygen (rCMRO2) in the bilateral fronto-temporal areas and in the left thalamus. These results suggest that dysfunction of the frontal-thalamic neural network plays a role in the disturbance of Korsakoff syndrome.

Alcohol Amnestic Disorder↗
PubMed1997

Hanshin-Awaji earthquake as a trigger for acute myocardial infarction.

On Jan. 17, 1995, the Hanshin-Awaji district was struck by the most destructive earthquake ever to occur in Japan. It is commonly believed that acute emotional stress such as that caused by an earthquake can trigger acute myocardial infarction (AMI). The objective of this study was to evaluate the effect of the quake stress on the onset of AMI in our district. The number of patients with AMI during the first 4 weeks after the quake increased by about 3.5-fold. The mean age of patients was 72.5 +/- 2.8 years, and the proportion of women (53%) was significantly greater than in the preceding years. The proportion of patients without prodromal angina pectoris was 53%. The mean post-traumatic stress disorder reaction index score (n = 14) was 40.1 +/- 4.1, which indicates a severe stress level. The mean score in the women (45.9 +/- 4.7; n = 7) was significantly higher than that in the men (34.3 +/- 6.4; n = 7). We concluded that after an earthquake, severe emotional stress can trigger AMI, more often than normal in women.

Aged↗
PubMed1997

The effects of prednisolone and interferons on serum macrophage colony stimulating factor concentrations in chronic hepatitis B.

BACKGROUNDS/AIMS: Serum concentrations of macrophage-colony stimulating factor (M-CSF) are increased in parallel with hepatic inflammation. The aim of this study was to assess the immunologic significance of elevated M-CSF in patients with chronic hepatitis B virus infection. METHODS: The subjects included 20 asymptomatic HBV carriers and 45 patients with chronic hepatitis B, including 8 undergoing prednisolone treatment, 10 experiencing an acute exacerbation, and 12 undergoing daily administration of interferons. RESULTS: Serum concentrations of M-CSF significantly decreased during prednisolone administration, but significantly increased following prednisolone withdrawal, similar to the increase during acute exacerbation. Changes in the lipopolysaccharide-stimulated production of interleukin-1-beta and tumor necrosis factor-alpha by peripheral whole blood, or of interferon-gamma by peripheral blood mononuclear cells showed a similar pattern. Serum concentrations of M-CSF did not correlate with the titers of HBV-DNA or HBV-DNA polymerase activity. However, serum M-CSF peaked preceding seroconversion to HBe antibody in three HBe antigen positive patients. Exogenous interferon-alpha, -beta, or -gamma induced significant elevation in serum M-CSF concentrations, irrespective of changes in the serum alanine aminotransferase levels. CONCLUSIONS: Increased serum M-CSF is closely associated with increased serum interferons and/ or proinflammatory cytokines produced by peripheral blood cells during hepatic inflammation in chronic hepatitis B. This may be a consequence of the altered cytokine cascade resulting from the host immune response against hepatitis B virus.

Adolescent↗
PubMed1997

Intercellular adhesion molecule-1 and CD18 are involved in neutrophil adhesion and its cytotoxicity to cultured sinusoidal endothelial cells in rats.

The expression of several adhesion molecules is increased on the hepatic sinusoidal endothelial cells (SECs) in various liver diseases. The objective of this study is to assess the roles of intercellular adhesion molecule 1 (ICAM-1) and of CD18 in the interaction between the neutrophils (polymorphonuclear leukocytes [PMNs]) and SECs and in the injury to SECs mediated by PMNs. Rat PMNs was perfused on SECs stimulated with tumor necrosis factor alpha (TNF-alpha) using an in vitro flow system. The number of adhered PMNs to SECs and that of PMNs migrated under SECs was counted and the effects of anti-ICAM-1, anti-CD18, and dexamethasone were studied. We also define the effect of these antibodies on the SEC injury mediated by PMNs stimulated with phorbol 12-myristate 13-acetate (PMA) or N-formyl-methionyl-leucyl-phenylalanine (fMLP). TNF-alpha significantly increased the adhesion of PMNs to SECs (322 +/- 26 cells/mm2) compared with controls (194 +/- 22 cells/mm2). Anti-ICAM-1 and anti-CD18 significantly inhibited the adhesion of PMNs (131 +/- 10 and 51 +/- 30 cells/mm2, respectively). These antibodies also decreased the migration rate of PMNs (6.0% and 7.9%, respectively) compared with controls (migration rate, 21.2%). The SEC injury induced by PMA- and fMLP-activated PMNs was prevented by anti-ICAM-1 and anti-CD18. The adhesion of PMNs induced by TNF-alpha was inhibited by the treatment with dexamethasone (160 +/- 20 cells/mm2) via a down-regulation of ICAM-1 expression on SECs. The interactions between ICAM-1 and CD18 appeared to be important in the adhesion and the migration of PMNs to SECs. The injury to SECs was induced by the close interaction between the activated PMNs and SECs mediated via ICAM-1 and CD18.

Animals↗