Biomedical subjects

N Yamamoto

Publications and source records attributed to N Yamamoto.

At least 271 records · Page 15Linked to original sources

PubMed1999

Outcome of target sites escaping high-grade (>70%) restenosis after percutaneous transluminal coronary angioplasty.

This study examined the fate of target sites that escaped high-grade restenosis (> or = 70% diameter narrowing) after percutaneous transluminal coronary angioplasty. Although favorable long-term prognosis after successful percutaneous transluminal coronary angioplasty is well documented, little is known about the stability of target sites. Long-term follow-up (mean 6.5 years, range 1.0 to 12.0) was performed in 693 patients with 948 narrowings (stenosis <70% in diameter at follow-up coronary angiography). Among them, 249 patients (36%) with 303 target sites received late follow-up coronary angiography. The relation of target sites to the culprit lesions for coronary events or newly developed angina was angiographically reviewed and progression/regression was also examined, focusing on the target sites. Regression was observed in 16 of 255 target sites in subjects with <50% stenosis and in 21 of 48 sites in the group with midgrade stenosis of 50% to 69% luminal narrowing (16 of 255, 6.3% vs 21 of 48, 43.8%, p <0.001). Progression was observed in 33 and 4 sites (33 of 255, 12.9% vs 4 of 48, 8.3%; p = NS) in each group, respectively. The rest remained within the same range of stenosis. Culprit lesions for 2 acute myocardial infarctions, 7 unstable anginas, and 17 newly developed anginas were related to the original target sites. Three lesions developed in the midgrade stenosis group. Those 26 lesions were a component of 8.6% of 303 angiographically confirmed sites and 2.7% of total target sites. Target sites that escape high-grade restenosis frequently regress and become stable plaques and rarely trigger coronary events.

Aged↗

PubMed1999

Synthesis of sulfated oligosaccharide glycosides having high anti-HIV activity and the relationship between activity and chemical structure.

Sulfated laminara-oligosaccharide glycosides having high anti-human immunodeficiency virus (HIV) activities were synthesized from laminara-tetraose, -pentaose and -hexaose. The oligosaccharide glycosides were synthesized by treating peracetylated beta-oligosaccharides with various alcohols and Lewis acid catalysts. The effects of the number of glucose residues and the alkyl chain-length on anti-HIV activity were examined. The anti-HIV activity of sulfated dodecyl laminara-pentaosides and -hexaosides increased with increasing degree of sulfation (DS) and the pentaoside having an almost fully-sulfated saccharide portion had the highest activity, whereas for the hexaoside a somewhat lower DS manifested the highest activity. Sulfated laminara-oligosaccharide glycosides having fluoroalkyl-containing aglycons of high hydrophobicity showed potent inhibitory effects against HIV infection. In contrast, hydrophilic substituents containing oligo(ethyleneoxy) groups as aglycons in the sulfated oligosaccharides did not show high anti-HIV activity.

Anti-HIV Agents↗

PubMed1999

C-reactive protein: a physiological activator of interleukin 6 receptor shedding.

The soluble interleukin 6 receptor (sIL-6R) circulates at elevated levels in various diseases. This suggests that inflammatory mediators control sIL-6R release. Through examination of human neutrophils, it was found that the acute phase reactant C-reactive protein (CRP) activates a threefold increase in sIL-6R production. Maximal release occurred after 30-60 min exposure to CRP (50 micrograms/ml), and was mimicked by peptides corresponding to amino acid residues 174- 185 and 201-206 of native CRP. A third peptide fragment (77-82) had no effect. Differential mRNA splicing did not account for the CRP-mediated release of sIL-6R, since this isoform was not detected in conditioned media. Furthermore, stimulation of neutrophils with CRP or with peptides 174-185 or 201-206 promoted a loss of membrane-bound IL-6R, suggesting release by proteolytic shedding. The metalloprotease inhibitor TAPI had only a marginal effect on CRP-mediated sIL-6R release, suggesting that shedding occurs via a mechanism distinct from that previously reported. It well established that IL-6 stimulates the acute phase expression of CRP. Our current findings demonstrate a novel relationship between these two mediators, since CRP may affect IL-6-mediated inflammatory events by enabling formation of the sIL-6R/IL-6 complex.

Acute-Phase Reaction↗

PubMed1999

Identification and cloning of a novel cellular protein Naf1, Nef-associated factor 1, that increases cell surface CD4 expression.

The nef gene of human and simian immunodeficiency virus is a key factor in acquired immunodeficiency syndrome pathogenesis and virus replication. Several Nef-induced phenomena, including the down-regulation of CD4 molecule, have been previously reported. In this study, we have identified and cloned a novel cellular protein Naf1 (Nef-associated factor 1), which associated with Nef in the yeast two-hybrid system and pull-down assay. The Naf1 gene generates two isoforms (Naf1alpha and beta) containing four coiled-coil structures. The Naf1 mRNA is ubiquitously expressed in human tissues with strong expression in peripheral blood lymphocytes and spleen. Naf1 overexpression increased cell surface CD4 expression. Nef suppressed this Naf1-induced augmentation of CD4 expression, providing a novel mode of Nef action in CD4 down-regulation.

Amino Acid Sequence↗

PubMed1999

Acute exercise causes mitochondrial DNA deletion in rat skeletal muscle.

The present study was conducted to determine the effects of acute overload exercise on mitochondrial DNA and the structure of skeletal muscles. Rats were forced to run for 20 min until reaching complete exhaustion. We detected the large-scale deletion (7052 bp) of mitochondrial DNA by the nested polymerase chain reaction, and also observed mitochondrial ultrastructural changes in the soleus muscle.

Animals↗

PubMed1999

Antihypertensive peptides derived from milk proteins.

This paper reviews the angiotensin I-converting enzyme inhibitory peptides originated from milk proteins. Focus was put on the peptides derived from milk casein by the action of some proteolytic enzymes and fermented products by lactic acid bacteria. Some of the angiotensin I-converting enzyme inhibitory peptides exhibit significant antihypertensive effects in spontaneously hypertensive rats. However, there were some antihypertensive peptides with low inhibitory activity of this enzyme. Key factors needed for the peptide to demonstrate the antihypertensive effects are discussed. Fermented milk, which has inhibitory activity of the enzyme, showed the reduction of blood pressure of hypertensive subjects. The possibility of the bioactive peptides for functional foods are also discussed.

Amino Acid Sequence↗

PubMed1999

Application of intravascular ultrasonography for intracaval tumor thrombectomies in adrenal metastasis from hepatocellular carcinoma: report of two cases.

Intracaval tumor thrombus is one of the characteristic features of advanced hepatocellular carcinoma. To formulate an appropriate operative strategy for removing intracaval tumor thrombi, it is of great importance to accurately diagnose the location, any invasion into the wall of the vena cava, and the extent of intracaval tumor spread. Intravascular ultrasonographic imaging is a novel technology that enables the precise catheter-based assessment of the dimensions and morphology of the vascular structure and any lesions. We have applied this technology to the diagnosis of intracaval tumor thrombi originating from adrenal metastasis secondary to hepatocellular carcinomas. This modality was thus found to be useful in determining the best operative procedure for removing tumor thrombi in the inferior vena cava.

Adrenal Gland Neoplasms↗

PubMed1999

Right hepatic lobectomy for hepatocellular carcinoma which developed in primary biliary cirrhosis: report of a case.

The case of a 74-year-old female patient who underwent a right hepatic lobectomy for hepatocellular carcinoma (HCC) which developed in primary biliary cirrhosis (PBC) is reported herein. During a follow-up examination for Parkinson's disease, an elevation of hepatobiliary tract-related enzymes and alpha-fetoprotein was uncovered. Diagnostic imagings showed a hypervascular, solitary, and encapsulated tumor measuring about 7 cm in diameter located mainly in the posterior segment. Positive antimitochondrial and antinuclear antibodies and a preoperative liver biopsy strongly suggested well differentiated HCC developed in PBC (Scheuer's classification stage II). Since the natural prognosis of PBC estimated by the Mayo risk score was fairly good and the liver function indicated sufficient tolerance for major hepatic resection, and preoperative computed tomography (CT) volumetry showed the atrophy of the right hepatic lobe, a right hepatic lobectomy was performed. A pathological examination revealed well encapsulated, moderately differentiated HCC with, in part, well-differentiated HCC in the tumor and stage II PBC in the noncancerous region. CT volumetry performed at postoperative day 14 showed a 146% enlargement of the remnant liver. An early detection of HCC and PBC by strict screening would prevent a limitation of surgical therapy due to a deteriorated liver function.

Aged↗

PubMed1999

Management of adrenal metastasis of hepatocellular carcinoma by asynchronous resection of bilateral adrenal glands.

We report on a 65-year-old man who received asynchronous bilateral adrenalectomy for adrenal metastasis of hepatocellular carcinoma. Fifteen months after curative resection of right hepatic lobe for hepatocellular carcinoma, a metastatic lesion of the left adrenal gland was detected and left adrenalectomy was performed. Ten months after the second operation, a metastatic lesion in the right adrenal gland, associated with tumor thrombus in the inferior vena cava, was revealed. Transcatheter arterial embolization of the arteries feeding the metastatic tumor was performed, but its effects were incomplete. As there was the tumor thrombus in the inferior vena cava and no other intrahepatic recurrence or extrahepatic metastasis was found, resection of the right adrenal gland with tumor thrombus, without the employment of veno-venous bypass, was performed, followed by postoperative hormonal supplementation. Changes in the patient's alpha-fetoprotein level were clinically useful for the detection of the metastatic lesions and the evaluation of therapeutic effects. Metastasis to adrenal gland from hepatocellular carcinoma should be actively managed, and the appropriate surgical treatment selected, if intrahepatic recurrence and/or other extrahepatic metastasis are controlled. To achieve higher curability and better outcome in patients with bilateral adrenal metastasis of hepatocellular carcinoma, bilateral total adrenalectomy is indicated, accompanied by effective postoperative hormonal supplementation.

Adrenal Gland Neoplasms↗

PubMed1999

Local effects of transforming growth factor-beta1 on rat calvaria: changes depending on the dose and the injection site.

Transforming growth factor-beta1 (TGF-beta1) has opposite effects on osteoblastic cells in vitro, namely an inhibitory or stimulatory effect on cell differentiation. Because these effects are dependent on TGF-beta1 concentration or culture condition, we investigated whether the in vivo effects of TGF-beta1 on bone formation in infant rat calvaria were affected by the dose or the injection site. Human platelet-derived TGF-beta1 was injected subcutaneously onto the periosteal surface of parietal bone of 4-week-old rats at doses of 5 or 20ng/100microl per animal for 14 days, and the local effect on bone formation was examined by bone histomorphometry. TGF-beta1 treatment for 7 days decreased the mineral apposition rate, bone formation rate, and elongated mineralization lag time at the injection site. This change became more prominent when treatment continued for 14 days. These changes were restricted to the TGF-beta1-exposed area. Multiple subcutaneous injections of a relatively high dose (200ng/100microl per animal) of TGF-beta1 induced woven bone formation, in addition to marked inhibition of bone formation rate and prolongation of mineralization lag time. On the other hand, direct exposure of TGF-beta1 in the subperiosteal layer induced woven bone with periosteal cell proliferation even at a single injection of a low dose (5 or 50ng/25 microl) of TGF-beta1. In conclusion, the in vivo effects of TGF-beta1 on bone formation varied depending on its concentration and injection site. Also, subcutaneous injection of relatively low doses of TGF-beta1 inhibited local lamellar bone formation.

Animals↗

PubMed1999

Urinary excretion of the vitronectin receptor (integrin alpha V beta 3) in patients with Fabry disease.

A renal disorder is one of the important manifestations of Fabry disease, but the details of the pathogenesis have not been clarified yet. We examined the possibility that the vitronectin receptor (VNR, integrin alpha V beta 3), one of the integrins, is involved in the progression of the renal injury in Fabry disease. We measured the urinary excretion of beta 3 originating from VNR in Fabry patients by immunoblotting analysis and enzyme-linked immunosorbent assay (ELISA). Immunofluorescent microscopic analyses for VNR and globotriaosylceramide were performed on urinary sediments from Fabry patients. Furthermore, beta 3 and vitronectin in kidney tissues were analyzed immunohistochemically. Immunoblotting analysis and ELISA showed that the urinary excretion of beta 3 originating from VNR was significantly increased in the Fabry group compared with both the pathological and healthy control groups. Immunofluorescent microscopy revealed the expression of VNR and accumulation of globotriaosylceramide in urinary sediments from the Fabry patients. Increased expression of beta 3 was observed in glomerular epithelial cells, and in Bowman's capsular epithelial layer and tubular cells, and the amount of vitronectin was moderately increased in the kidney tissues from the Fabry patients. The urinary excretion of VNR was increased, and the expression of VNR was observed in Fabry kidney tissues. The expression of VNR may be involved in the progression of the renal injury in this disease.

Adolescent↗

PubMed1999

Expression of Epstein-Barr virus in mesopharyngeal and hypopharyngeal carcinomas.

Epstein-Barr virus (EBV) causes various tumors, including nasopharyngeal carcinoma (NPC). There have been no reports as to whether the carcinogenicity of EBV is restricted to the nasopharynx or extends into the mesopharynx and hypopharynx. We attempted to ascertain the relation between EBV and mesopharyngeal (MPC) and hypopharyngeal carcinomas (HPC). Messenger RNA in situ hybridization showed that all 29 cases of MPC and 5 of 12 HPC expressed EBV mRNA. For further analysis, we established 7 cell lines from 5 MPC and 2 HPC. All cell lines and 5 tumors formed by these cultured cells in nude mice expressed EBV transcripts. Moreover, immunofluorescence staining showed expression of EBV-related nuclear antigen-2 and latent membrane protein-1 (LMP1) in the original tumors and the cell lines, as well as in nude mouse tumors. Study by reverse transcription polymerase chain reaction (RT-PCR) also showed EBER1 and LMP1 expression. Furthermore, lytic-cycle antigens of EBV were detectable in most cell lines. Nested PCR showed the EBV genome in 3 cases of MPC and 4 cases of HPC. These results suggest that EBV plays an important role in the development of MPC and HPC as well as in NPC.

Animals↗

PubMed1999

Müllerian duct cyst extending into the abdomen.

Müllerian duct cysts occupying the pelvic/abdominal region are rare. We describe a müllerian duct cyst extending into the lower abdomen in a 47-year-old man complaining of urinary retention. We removed the cyst through a suprapubic retrovesical approach. No malignancy was found in the surgical specimen.

Abdomen↗

PubMed1999

Induction of blood-brain barrier properties in immortalized bovine brain endothelial cells by astrocytic factors.

The blood-brain barrier (B-BB) protects the free passage of substances into the brain and maintains the homeostasis of the central nervous system. It is commonly accepted that astrocytes surrounding brain endothelial cells influence the B-BB formation and the exhibition of B-BB function of capillaries. To begin the in vitro study on the B-BB, it is essential to obtain a homogenous and sufficient supply of brain endothelial cells as well as astrocytes. We thus immortalized the bovine brain endothelial cell (BBEC) by transfection of the SV40 large T antigen and obtained a single clone, t-BBEC-117, which retained the brain endothelial cell phenotype. Astrocyte in co-culture was found to tighten the intercellular contacts of the immortal cells resulting in a reduced L-glucose permeability, and its conditioned medium (CM) augmented a B-BB phenotype, alkaline phosphatase (ALP) activity. Among known astrocytic factors, only fibroblast growth factor-basic (bFGF) could mimic the actions of astrocytes as measured by L-glucose permeability and ALP activity. Moreover, anti-bFGF antibody canceled 90% of ALP activation by astrocyte CM. Basic FGF, however, failed to induce other B-BB phenotypes such as the expressions of multidrug resistance (mdr) and glucose transporter (GLUT-1) genes. These data suggest that bFGF is one of the most plausible astrocytic factors to induce the B-BB properties of immortal brain endothelial cells together with some unknown factors in the astrocyte CM.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

Gene transfer to the rat biliary tract with the HVJ-cationic liposome method.

BACKGROUND/AIMS: The ability to transfer foreign genes into the biliary tract would be useful for the treatment of biliary tract diseases, including cancer, cystic fibrosis and other genetic diseases. To introduce a foreign gene precisely into the rat biliary epithelial cells, we developed a new technique, inserting a polyethylene catheter into the common bile duct through the papilla of Vater by use of a fusigenic cationic liposome with hemagglutinating virus of Japan (HVJ-cationic liposome). METHODS: Transfection efficiency was estimated with the use of FITC-oligonucleotides (FITC-ODNs) and cDNA of beta-galactosidase (pCAG-lacZ). RESULTS: FITC-ODNs encapsulated in HVJ-cationic liposome were effectively transfected into cell nuclei of human cholangiocellular carcinoma in vitro after a 30-min incubation as compared with the simple application of naked FITC-ODNs. After in vivo injection of FITC-ODNs using the HVJ-cationic liposome method through the papilla of Vater, fluorescence accumulation was observed only in the epithelial cells of the biliary tract, but not in the parenchymal cells of the liver. Beta-galactosidase expression was observed in the biliary epithelial cells 3 days after the transfection of pCAG-lacZ and was also detected at 14 days, but not at 28 days, without obvious cytotoxicity. CONCLUSIONS: HVJ-cationic liposome-mediated gene transfer to the biliary tract via the papilla of Vater is a minimally-invasive and an effective gene-delivery method for site-specific targeting to the epithelial cells of the biliary tract, which could be applied to the treatment of human biliary tract diseases.

Animals↗

PubMed1999

Mechanical properties of collagen fascicles from stress-shielded patellar tendons in the rabbit.

OBJECTIVE: To know the effects of stress shielding applied to the patellar tendon on the collagen fascicles. DESIGN: The mechanical properties of collagen fascicles obtained from stress-shielded patellar tendons were compared to those of collagen fascicles from non-treated patellar tendons and those of stress-shielded bulk patellar tendons in the rabbit. BACKGROUND: Effects of stress deprivation and stress enhancement on the mechanical properties of knee joint tendons and ligaments have been extensively studied in various animal models. However, the roles of such substructural components as collagen fascicles in the remodeling of tendons and ligaments have not been studied well. METHOD: Tensile and viscoelastic properties of collagen fascicles obtained from the rabbit patellar tendons which were completely stress-shielded for 1 to 3 weeks by a special method developed by the authors were determined using a micro tensile tester. RESULTS: Stress shielding significantly decreased the tangent modulus, tensile strength, and strain at failure of collagen fascicles. However, these changes were much smaller than those observed in bulk tendons. The relaxation of stress-shielded collagen fascicles was greater than that of non-treated ones. CONCLUSIONS: Ground substance and mechanical interaction between collagen fascicles have important roles in the remodeling of tendons and ligaments. RELEVANCE: Knowledge of the role of such substructural components as collagen fascicles in the remodeling of tendons and ligaments is essential not only to the basic biomechanics of knee joint tendons and ligaments but also to the development of their reconstruction methods using autografts.

Animals↗

PubMed1999

Echogenicity of fetal lung and liver quantified by the grey-level histogram width.

Grey-level histogram width (GLHW) values of fetal lung and liver were studied in 52 healthy fetuses in 24 to 38 weeks of pregnancy, comparing them to the mean grey level (MGL), grey-level standard deviation (GLSD) and the coefficient of variation (GLCV). Fetal lung GLHW was larger in 30-38 weeks than at 24-29 weeks, but there was no change in liver GLHW. GLHW was smaller in fetal lung than in the liver in 24-29 weeks, with no difference in 30-38 weeks. The lung/liver GLHW ratios were less than 1 in 24-29 weeks, but they were 1 or more in 30-35 weeks. Both MGL of fetal lung and liver showed linear increases during pregnancy, but no difference was found between the two. Fetal lung GLSD tended to decrease during pregnancy. The GLCV values of fetal lung and liver decreased during pregnancy, and differed between 24-29 weeks and 30-38 weeks, whereas there was no difference between fetal lung and liver. The correlation coefficients of GLHW and MGL of fetal lung and liver to the weeks of pregnancy were moderate, and the coefficients of GLSD and GLCV to the weeks of pregnancy were small. In conclusion, quantitatively measured echogenicity of fetal lung increased in 30 or more weeks of pregnancy, and suggested antepartum changes of fetal lung tissue. The GLHW is reliable, because it was reproducible in various gain settings of various ultrasonic imaging devices. The MGL, GLSD and GLCV are less reliable, because the grey level varied by the gain changes among various machines.

Embryonic and Fetal Development↗

PubMed1999

Mechanisms for generating the autonomous cAMP-dependent protein kinase required for long-term facilitation in Aplysia.

The formation of a persistently active cAMP-dependent protein kinase (PKA) is critical for establishing long-term synaptic facilitation (LTF) in Aplysia. The injection of bovine catalytic (C) subunits into sensory neurons is sufficient to produce protein synthesis-dependent LTF. Early in the LTF induced by serotonin (5-HT), an autonomous PKA is generated through the ubiquitin-proteasome-mediated proteolysis of regulatory (R) subunits. The degradation of R occurs during an early time window and appears to be a key function of proteasomes in LTF. Lactacystin, a specific proteasome inhibitor, blocks the facilitation induced by 5-HT, and this block is rescued by injecting C subunits. R is degraded through an allosteric mechanism requiring an elevation of cAMP coincident with the induction of a ubiquitin carboxy-terminal hydrolase.

Animals↗