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Biomedical subjects

F Nakano

Publications and source records attributed to F Nakano.

17 recordsLinked to original sources
PubMed1999

Morphological effects on in-stent restenosis assessed by intravascular ultrasound imaging.

The purpose of this study was to evaluate the rupture and dissection of the vessel wall immediately after balloon dilatation by intravascular ultrasound (IVUS) imaging and to predict restenosis in patients who underwent subsequent coronary stent implantation. Stent implantation improves the long-term results of coronary angioplasty by reducing lesion elastic recoil and arterial remodeling. However, several studies have suggested that neointimal hyperplasia is the cause of instant restenosis. We recruited 60 patients in whom IVUS studies were performed immediately after successful balloon dilatation and just before stent implantation. We compared IVUS parameters with 6-month follow-up quantitative coronary angiography. This was performed in 51 lesions of 51 patients (85%). Qualitative analysis included assessment of plaque composition, plaque eccentricity, plaque fracture and the presence of dissection. In addition, minimal luminal diameter, percent diameter stenosis, percent area stenosis and plaque burden were quantitatively analyzed. Two morphological patterns after balloon dilatation were classified by IVUS. Type I was defined as absence or partial tear of the plaque without disclosure of the media to lumen (22 lesions). Type II was defined as a split in the plaque or dissection of the vessel wall with disclosure of the media to the lumen (29 lesions). At 6 months follow-up, angiographic restenosis occurred in 17 of the 51 lesions (33%). Restenosis was significantly (p < 0.05) more likely to occur in type II (13/29: 45% incidence) than in type I (4/22: 18% incidence). The assessment of plaque morphology immediately after balloon dilatation and before stent implantation provides important therapeutic and prognostic implications.

Aged↗
PubMed1999

Reinforcement mechanism of dentin mechanical properties by intracanal medicaments.

The reinforcement mechanism of dentin mechanical properties by intracanal medicaments was investigated. The dumbbell-shaped specimens were prepared from a collagen sheet, demineralized dentin and organic dissolved dentin. After immersing the specimens in intracanal medicaments (eugenol and formocresol), the tensile test was carried out in 37 degrees C water and the Vickers hardness test was performed. The tensile strengths increased after eugenol and formocresol immersion, especially collagen and organic dissolved dentin after formocresol immersion and demineralized dentin after eugenol immersion. Thus, formocresol immersion might have reinforced the dentin tensile strength by protein coagulation, while eugenol immersion might have reinforced the dentin tensile strength by not only protein coagulation but also chelation with hydroxyapatite. However, the hardness values did not significantly change after intracanal medicament immersion.

Analysis of Variance↗
PubMed1999

[Clinical manifestations and chest radiographic and CT findings of round pneumonia in adults].

Whereas round pneumonia in children is well known, there are few reports of this condition in adults. Chest radiographs, CT findings, clinical manifestations, and peripheral blood results in 14 cases of round pneumonia in 14 adults were evaluated. Round pneumonias ranged in size from 1 to 7 cm. Only round pneumonia was seen in 12 cases, whereas other consolidations besides round pneumonia were present in 2 cases. Eleven of 14 cases of round pneumonia were located in the lower lobes, and 8 of these 11 cases were in the superior segment of the lower lobe. Round pneumonia showed faint density in 9 cases and clear density in 5, while the margin was slightly ill-defined in 10 and well-defined in 4. No characteristic features of round pneumonia were shown on CT scan. CT showed other consolidations besides round pneumonia in 7 of 9 cases in which CT scan was carried out. Most large-sized (more than 2 cm) round pneumonias were associated with fever and elevated WBC and CRP, whereas most small (less than 2 cm) round pneumonias were associated with normal blood results and no fever. Round pneumonia in adults is not uncommon. Most round pneumonias present as slightly dense or ill-defined masses in the posterior subpleural region of the lower lobe. Round pneumonia is suggested by a history of cough, fever, elevated WBC and CRP, and a recent chest radiograph with normal findings.

Adult↗
PubMed1998

A new criterion combining ST/HR slope and deltaST/deltaHR index for detection of coronary artery disease in patients on digoxin therapy.

We evaluated the clinical value of a new index combining deltaST/delta heart rate (HR) index and ST/HR slope for diagnosing coronary artery disease (CAD) in patients on digoxin therapy. Exercise treadmill tests were performed by 72 patients on digoxin therapy. Simple HR-adjusted indexes of ST-segment depression during exercise (deltaST/deltaHR index) and the decline calculated from the final 12 data points relating ST-segment depression to HR (ST/HR slope) were determined. A new index was obtained by subtracting the deltaST/deltaHR index from the ST/HR slope. On thallium scintigraphy, 37 of the 72 patients showed reversible perfusion defects related to the diseased coronary artery. The new index derived from this ST-HR relation was 4.1 +/- 3.6 microV/beats/min in the ischemic group and 1.3 +/- 1.0 microV/beats/min in the group of patients without ischemia (p <0.0001). An ST-HR relation > or = 1.5 was found in 33 of the 37 patients in the ischemic group, and in 7 of the 35 patients without ischemia (p <0.0001). The sensitivity of this criterion for prediction of myocardial ischemia was 89%, the specificity was 80%, and the predictive accuracy was 85%. Thus, this new ST-HR index is useful for detecting CAD in patients on digoxin therapy.

Aged↗
PubMed1998

Isolation and chemical composition of the sheath of Sphaerotilus natans.

A sheathed bacterium, Sphaerotilus natans, was cultured with vigorous shaking in a medium containing peptone. Then the biomass was harvested and treated with lysozyme, sodium dodecyl sulfate, and protease. With treatment, 1.6 mg of sheaths was obtained from 15 mg of biomass. For the preparation of sheaths of high purity, cultivation must be in the absence of glucose with sufficient aeration to prevent poly(3-hydroxybutyrate) accumulation. Carbohydrate (54.1%), protein (12.2%), and lipid (1-3%) were detected in the sheaths by colorimetric reactions and solvent extraction. Gas-liquid chromatography showed glucose and galactosamine to be present in the molar ratio of 1:4. The most abundant amino acids in the sheath protein were glycine (49.2 mol%) and cysteine (24.6 mol%). The sheaths were resistant to agents that reduce disulfide bonds (dithiothreitol and 2-mercaptoethanol) and to protease. However, sheathes were degraded completely by hydrazine, and a heteropolysaccharide composed of glucose and galactosamine (1:4) was released. The weight-average molecular weight of the polysaccharide was estimated to be 1.2 x 10(5) by gel filtration chromatography with a low-angle laser-light scattering photometer and a rotation index detector. A ladder of 1.5-kDa peptides separable by sodium dodecyl sulfate gel electrophoresis was obtained by partial hydrolysis of sheaths, suggesting the sheath protein has repeating units of 1.5 kDa.

Amino Acids↗
PubMed1997

Mechanisms of limited maximum coronary flow in severe single-vessel coronary artery disease in humans due to vertical steal.

We evaluated the usefulness of a decrease in the average peak velocity from 4 to 10 minutes after infusion of dipyridamole for detecting myocardial ischemia in 50 patients, including patients with a prior myocardial infarction. The decrease in the average peak velocity from 4 to 10 minutes associated with vertical steal and combined with a coronary flow reserve of < 1.6 had a high predictive value for myocardial ischemia in patients with or without prior myocardial infarction.

Aged↗
PubMed1997

Structure-function analysis of the diphtheria toxin receptor toxin binding site by site-directed mutagenesis.

Diphtheria toxin (DT) binds to the epidermal growth factor (EGF)-like domain of human membrane-anchored heparin-binding EGF-like growth factor (proHB-EGF), the human DT receptor (DTR). DT does not bind to mouse proHB-EGF because of amino acid substitutions within the EGF-like domain. We made 10 independent mutants, replacing a single amino acid within the EGF-like domain of human DTR/proHB-EGF with the corresponding amino acid residue in mouse proHB-EGF. The mutant proteins were transiently expressed in mouse L cells either expressing or not expressing DRAP27/CD9, and DT binding was measured. DT binding activity of GST fusion proteins containing the mutated EGF-like domain was also determined by a cell-free binding assay. The largest effect was seen with E141H, and second largest effects were seen with F115Y and L127F in all of the assay systems. We conclude that Phe115, Leu127, and Glu141 are critical amino acid residues for DT binding. A computer model of the tertiary structure of the EGF-like domain of human DTR/proHB-EGF was made. The model predicts that three amino acid residues critical for DT binding activity, Phe115, Leu127, and Glu141, are all located on the same face of the EGF-like domain, suggesting that this face of DTR/proHB-EGF interacts with the receptor-binding domain of DT.

Amino Acid Sequence↗
PubMed1997

c-myc activates RCC1 gene expression through E-box elements.

Proto-oncogene c-myc is implicated in proliferation of mammalian cells. Although c-Myc protein has been demonstrated to function as a transcription factor recognizing an E-box (CACGTG) element, few c-myc-regulated genes have been identified and the specific role of c-myc is still unclear. RCC1 is necessary for mammalian cells to proliferate. Four CACGTG elements exist within 1.3 kb downstream of the major transcription start site for the human RCC1 gene in HeLa cells. Stimulation of HeLa cells with serum increased c-myc expression and RCC1 expression. Therefore the relationship between the expression of RCC1 and c-myc was investigated. Rat 3Y1 cells overexpressing c-myc contained about twice as much RCC1 mRNA as control cells. When a chimeric protein comprised of c-myc and the estrogen binding domain of estrogen receptor was activated by addition of 4-hydroxytamoxifen (OHT), expression of RCC1 mRNA increased twofold. To examine whether c-Myc functions through the CACGTG elements, a DNA fragment of RCC1 intron 4, exon 5 and part of intron 5 was joined to firefly luciferase cDNA to construct a reporter plasmid. In transient expression experiments using HeLa cells, co-transfection with c-myc stimulated the luciferase activity up to 2.5-fold in a dose-dependent manner. When the CACGTG elements in the reporter plasmid were destroyed, stimulation by c-myc was not observed. The four CACGTG elements did not contribute equally to the stimulation by c-myc. Gel retardation experiments suggest that c-Myc with Max binds to the CACGTG elements in the context of the RCC1 gene sequence in vitro. These results indicate that c-Myc can regulate expression of RCC1 through the E-box elements.

Animals↗
PubMed1987

Structure-activity relations of 4-fluoromethyl monobactams.

New monobactam compounds with fluoromethyl side chains at the 4-position were synthesized. These compounds showed strong antibacterial activity against Gram-negative bacteria including Pseudomonas aeruginosa and good stability to various beta-lactamases. The effect of replacement of the 1-carboxy-1-methylethoxyimino residue of aztreonam with various substituted groups, and of the configuration of the 3- and 4-position were examined. Substitution of a carboxycyclopropoxy group in the oxyimino moiety effected the most potent antibacterial activity. The cis congeners were not hydrolysed by any types of beta-lactamases including the oxyiminocephalosporin hydrolysing enzyme. Introduction of a fluorine atom in the methyl group at the 4-position increased the beta-lactamase stability of monobactams.

Bacteria↗
PubMed1984

A study on renal papillary necrosis experimentally produced by the Shwartzman mechanism in rabbits.

To produce renal papillary necrosis experimentally by means of the Shwartzman mechanism in rabbits, E. coli endotoxin was injected into the renal pelvis unilaterally through the ureter as a preparative procedure after pretreatment by local administration of alcohol, and the same endotoxin was given again 24 hours later, but intravenously this time via the ear vein, as a provocation. Marked necrosis was produced in the renal papillae, where many intravascular fibrin thrombi were found histologically. Such papillary necrosis was largely prevented by heparin administration, and this lesion was considered to be the univisceral Shwartzman reaction occurring in the renal papillae. The lesion produced in the new experimental system of renal papillary necrosis described here has a good similarity to that of human cases in etiology, pathogenesis and morphology. The present system may therefore be a good model of human renal papillary necrosis, and should be useful for future studies.

Animals↗
PubMed1975

Fatal lung scan in a case of pulmonary hypertension due to obliterative pulmonary vascular disease.

A young woman with pulmonary hypertension due to sclerodermatous pulmonary vascular disease died immediately following the injection of macroaggregated albumin labeled with 99-TC for a perfusion lung scan. Review of the literature suggests that patients with chronic pulmonary hypertension due to an obliterative pulmonary vascular disease are at risk of developing a serious reaction to perfusion lung scanning. Important factors which predispose to an adverse reaction to lung scanning are the size and dose of macroaggregated albumin particles in relation to the total cross-sectional area of the pulmonary vascular bed and a critical arteriolar lumen size.

Adult↗