Biomedical subjects

M Ueda

Publications and source records attributed to M Ueda.

At least 325 records · Page 18Linked to original sources

PubMed1998

Neointimal tissue response at sites of coronary stenting in humans: macroscopic, histological, and immunohistochemical analyses.

BACKGROUND: Experimental animal studies have shown that coronary stenting induces neointimal proliferation. However, the histopathological events after coronary stenting in humans have not been studied systematically. METHODS AND RESULTS: We investigated 11 stented coronary arteries (9 Palmaz-Schatz stents, 1 Wiktor stent, and 1 ACS Multi-Link stent) obtained from 11 patients who had died 2 days to 21 months after stenting. We focused on gross, histological, and immunohistochemical aspects of the repair processes. Two patients developed symptoms of restenosis. Serial sections were stained with antibodies against smooth muscle cells (SMCs), macrophages, and endothelial cells. At 9 and 12 days after stenting, the stent sites showed thrombus formation with early formation of neointima composed of abundant macrophages and alpha-actin-negative spindle cells. From 64 days on, all sites with stenting showed a distinct layer of neointima, albeit to varying degrees. In nonrestenotic lesions, neointimal thickening was markedly less than in restenotic lesions but without qualitative differences; the neointima contained macrophages but was composed predominantly of alpha-actin-positive SMCs. CONCLUSIONS: These observations strongly support the concept that neointimal proliferation in humans is a process of staged redifferentiation of SMCs, which may cause in-stent stenosis. Moreover, the exuberant neointimal proliferation with accumulation of macrophages and extensive neovascularization at sites of stent restenosis suggests a role for organization of mural thrombus.

Actins↗

PubMed1998

Apoptosis and tumor angiogenesis in cervical cancer after preoperative chemotherapy.

The correlation between apoptosis and tumor angiogenesis in uterine cervical cancer treated by preoperative intraarterial infusion chemotherapy (IAC) was investigated. Cervical cancer samples surgically obtained from 12 patients (stages Ib-IIIb) receiving IAC and from 10 patients (stages Ib-IIb) receiving no chemotherapy and biopsy specimens from the 12 patients before IAC were examined. The apoptotic index (AI) was determined with an in situ end-labeling assay. Intratumoral microvessel density (IMVD) and thymidine phosphorylase (dThdPase) expression were evaluated immunohistochemically using anti-CD34 and anti-dThdPase antibodies. AIs were higher in the 8 patients with complete or partial response to IAC than they were in the 4 nonchemoresponsive patients and in the 10 patients who received no chemotherapy (P < 0.01) and were inversely related to IMVDs (r = 0.724; P < 0.01). AIs and IMVDs after IAC were higher and lower than those before IAC (P < 0.01), respectively. The expression of dThdPase, which has angiogenic activity, was markedly decreased after IAC. These results suggest that the antitumor effects of IAC are closely associated with apoptotic cell death, which may be influenced in part by the extent of tumor angiogenesis inhibition.

Adult↗

PubMed1998

Inhibition of NMDA receptors and nitric oxide synthase reduces ischemic injury of the retina.

This study was performed to examine the roles of body temperature, NMDA receptors and nitric oxide (NO) synthase in post-ischemic retinal injury in rats. Cell loss in the ganglion cell layer and thinning of the inner plexiform layer were observed 7 days after ischemia. Cell loss in the ganglion cell layer but not thinning of the inner plexiform layer was reduced by hypothermia during ischemia. Intravenous injection of dizocilpine (MK-801) or Nomega-nitro-L-arginine methyl ester (L-NAME) prior to ischemia ameliorated retinal injury. These results suggest that activation of NO synthase following NMDA receptor stimulation is involved in ischemia-induced retinal injury.

Animals↗

PubMed1998

Peroxisomal and mitochondrial carnitine acetyltransferase isozymes of the n-alkane-assimilating yeast, Candida tropicalis, occurred by alternative initiation of translation from the transcripts of a single gene.

Carnitine acetyltransferase (CAT; EC 2.3.1.7) is localized in two subcellular organelles, peroxisomes and mitochondria, in an n-alkane-assimilating yeast, Candida tropicalis. The isozymes are synthesized from the first and second ATG codon of the open reading frame of one gene, CtCAT. Primer extension analysis and RNase protection assay (RPA) revealed that multiple transcription initiation sites were found upstream of the first ATG codon. 5' ends could not be detected between the first and second ATG codons. These results suggested that the peroxisomal CAT of C. tropicalis, initiating at the second AUG codon of the transcripts, was synthesized by a translational readthrough of the first AUG codon of the open reading frame. When CtCAT was introduced into the other yeast, Saccharomyces cerevisiae, 5' ends of transcripts and the protein products were similar to those observed in C. tropicalis. This suggested that the transcripts harbored sufficient information to bring about alternative initiation of translation in both yeasts. Using S. cerevisiae as the host cell, introduction of mutations into the sequence near the first AUG codon or a deletion in the region between the first and second AUG codons resulted in an increased ratio of translation from the first AUG codon, although initiation sites of transcription did not change. Moreover, replacing the 5' leader sequence to that of C. tropicalis isocitrate lyase promoter (UPR-ICL) eliminated the product initiating at the second AUG codon. The transcript from these cells was shorter than those detected from the native CtCAT-harboring cells. From these results, it was strongly suggested that peroxisomal and mitochondrial CAT isozymes occurred by the alternative initiation of translation mainly dependent on the structure and sequence context of the region from the 5' end to the second AUG codon, and not the insufficient length of the 5' leader.

Amino Acid Sequence↗

PubMed1998

Identification of heparin-binding stretches of a naturally occurring deleted variant of hepatocyte growth factor (dHGF).

A deleted variant of hepatocyte growth factor (dHGF) is a naturally occurring major variant of HGF, which lacks five consecutive amino acid residues in the first kringle domain. While both HGF and dHGF bind to heparin, the residues involved in the binding to heparin have not been identified in either protein. To identify the residues involved in the binding, we made a series of dHGF mutants in which basic residues in the N-terminal and the first kringle domains were replaced with alanine residue. The analysis of heparin-binding ability revealed that three stretches, 42RCTRNK in the hairpin loop structure, and 2RKRR and 27KIKTKK in the N-terminal basic region, are involved in the binding. Alanine substitution of each basic residue except 3K and 27K in the stretches reduced the heparin-binding ability of dHGF, and the decrease was additive. Conversely, lysine substitution of 37D, 38Q or 64Q in the N-terminal domain increased heparin-binding ability. These results suggest that stretches distant from each other in the primary structure come into close proximity when the polypeptide folds into protein, and form a heparin-binding site with clusters of basic residues.

Amino Acid Sequence↗

PubMed1998

The gene structure and promoter sequence of mouse hyaluronan synthase 1.

The structure and organization of mouse hyaluronan synthase 1 gene, HAS1 were determined by direct sequencing of lambda phage clones carrying the entire gene and by application of the long and accurate (LA)-PCR method to amplify regions encompassing the exon-intron boundaries and all of the exons. This gene spans about 11kb of genomic DNA and consists of 5 exons and 4 introns. A similarity in the exon-intron organization was found between the genes of mouse HAS1 and Xenopus laevis DG42 which was recently identified as Xenopus hyaluronan synthase. The transcription initiation site was determined by rapid amplification of the cDNA ends (5'-RACE). Position +1 is located 55 nucleotides upstream of the ATG initiation codon. The promoter region of the HAS1 gene has no typical TATA box, but contains a CCAAT box located 190 nucleotides upstream of the transcription initiation site. Further analysis of 1.4 kb of the 5' flanking region revealed several potential binding motifs for transcription factors. This information about the gene structure may be useful for further studies on the promoter activity.

Animals↗

PubMed1998

Magnetic resonance imaging of esophageal squamous cell carcinoma using magnetite particles coated with anti-epidermal growth factor receptor antibody.

A highly specific and effective magnetic resonance imaging (MRI) contrast agent was prepared by coating super-paramagnetite particles with monoclonal antibodies (MAbs) directed against epidermal growth factor receptors (EGFRs), which are over-expressed in esophageal squamous cell carcinoma. The preparation maintained both the immunoreactivity of the MAbs and the full relaxing capability of the magnetite particles. The particles of this EGFR-specific contrast agent are 13.2 +/- 1.9 nm in size, and thus, it is assumed that they are smaller than capillary pores and, hence, able to escape scavenging by reticulo-endothelial system cells. The EGFR-specific T2-relaxing ability of this contrast agent was ascertained first in vitro, using the EGFR-expressing cell line TE8 and the EGFR-deficient cell line H69. The results in athymic rats bearing TE8 or H69 tumors revealed that the agent has EGFR-specific MRI contrast capacity in vivo. The electron-microscopic findings in TE8 tumor-bearing rats revealed that the magnetite particles had been taken up by their lysosomes. In conclusion, immuno-specific MRI using magnetite particles coated with MAbs against EGFR appears to be useful in the diagnosis of squamous cell carcinoma of the esophagus.

Animals↗

PubMed1998

Surgical treatment for carcinoma of the thoracic esophagus with major involvement in the neck or upper mediastinum.

BACKGROUND AND OBJECTIVES: In carcinoma of the thoracic esophagus, most surgeons consider that esophagectomy is contraindicated in patients with clinical evidence of major extraesophageal involvement in the lower neck or peritracheal regions. However, metastases to these regions are commonly found even in early phases of carcinoma invasion. With recent progress in preoperative assessment, operative technique and adjuvant therapy, esophagectomy could possibly benefit appropriately selected patients. METHODS: We retrospectively analyzed results in 42 patients who had major involvement in the neck or upper mediastinum and who underwent esophagectomy with systematic lymph node dissection. We operated upon patients unless lesions were assessed as definitely unresectable. Preoperatively, 32 had enlarged peritracheal nodes greater than 15 mm in diameter on computed tomography, 18 had hard unmobile tumors in the lower neck, 9 had recurrent laryngeal nerve palsy, and 10 had findings suggestive of tracheal invasion. Preoperative radiotherapy and/or chemotherapy was given to 32 low-risk patients. RESULTS: The hospital mortality rate was 4%. Bowel reconstruction was completed in all cases. No macroscopically recognizable lesion remained after operation in 35 patients. Eight patients were alive 5 years after esophagectomy, including 2 who had had tracheal invasion and 1 with recurrent nerve palsy. The cumulative 5-year survival was 38%. CONCLUSIONS: Evidence of major involvement of the neck and/or upper mediastinum does not always contraindicate resection. Aggressive esophagectomy combined with perioperative adjuvant therapy yielded acceptable palliation and occasional cure in cases with technically resectable lesions.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1998

Brush cytology of herpes simplex virus infection in oral mucosa: use of the ThinPrep processor.

Evaluation was made of oral scraping specimen using Cytobrush from 11 patients with clinical suspicious lesions for herpes simplex virus (HSV) infection. In this study, oral brush cytology prepared using an automated smear apparatus (ThinPrep method) has been applied. The smears prepared by ThinPrep are equally well suited for screening purposes, producing highly cellular specimens with well-preserved cytoplasm and nuclei. The results obtained on the 11 patients, four cytologic specimens, showed pathognomonic viral cellular changes of HSV infection. Viral isolation studies were performed on 10 of the 11 patients and ten specimens tested positive for HSV by culture. Of the ten HSV positive isolates, six were positive by either cytology or immunocytochemical staining. Of the two smears showing HSV positive cells, both smears were also confirmed by in situ hybridization (ISH) with a biotinylated clone DNA probe. Using the ICC technique, detection of HSV antigen in oral scraping smears was of great value in the diagnosis of oral HSV infection, especially in cases of equivocal lesions. Oral cytology by means of ThinPrep method obviously deserves additional trials as an adjunct in the cytology of HSV-suspected lesions.

Cytodiagnosis↗

PubMed1998

Inhibition of angiogenesis on glycated collagen lattices.

Advanced glycation endproduct (AGE) accumulation in extracellular matrix proteins has been demonstrated in diabetic patients with a significant correlation with the severity of diabetic complications. AGE accumulation induces matrix protein cross-link formation, resulting in an increased stiffness of matrix fibres and the reduction of the susceptibility of matrix proteins to proteolytic degradation. We examined whether glycation-induced collagen cross-linking may affect vascular endothelial cell behaviours such as invasion, proliferation and differentiation, using the in vitro angiogenesis model of capillary-like structure formation in three-dimensional matrices of collagen type I. Endothelial cells cultured on collagen gel with angiogenic factors (the combination of fibroblast growth factor-2 and vascular endothelial growth factor) invaded the underlying collagen matrix, and organized capillary-like cord structures in the gel. We found that endothelial cell invasion into glycated collagen gel was significantly attenuated without any effect on proteinase activity including cell-associated plasminogen activator and matrix metalloproteinase in the conditioned medium. In addition, subsequent capillary-like cord formation was also inhibited in glycated collagen gel. In contrast, endothelial cell proliferation was enhanced on glycated collagen gel with or without angiogenic factors compared with control collagen gel. These results suggest that the structural alterations of extracellular matrix proteins through the glycation-induced cross-link formation affect the interaction between endothelial cell and extracellular matrix, resulting in the impairment of an adequate neovascularization in diabetic patients.

Angiogenesis Inducing Agents↗

PubMed1998

Mechanism of the pathogenesis of glutamate neurotoxicity in retinal ischemia.

PURPOSE: This study was carried out to examine the involvement of glutamate and nitric oxide neurotoxicity in ischemia/reperfusion-induced retinal injury in vivo. METHODS: We monitored glutamate release from in vivo cat retina during and after pressure-induced ischemia using a microdialysis technique. Morphometric studies were performed to study the effects of MK-801 (dizocilpine), L-NAME (N omega-nitro-L-arginine methyl ester), and D-NAME (N omega-nitro-D-arginine methyl ester) on the histological changes in the rat retina induced by ischemia or intravitreal injection of NMDA (N-methyl-D-aspartate; 200 nmol). RESULTS: A large release of glutamate occurred during ischemia, followed by a marked release after reperfusion. Histological changes occurred selectively in the inner part of the retina after ischemia as well as intravitreal injection of NMDA. Pretreatment with intravenous injection of MK-801 or L-NAME significantly inhibited the ischemic injury of the inner retina. Intravitreal injection of L-NAME inhibited NMDA-induced neurotoxicity in the retina. CONCLUSION: These findings indicate that nitric oxide mediates neurotoxic actions of glutamate which are responsible for ischemic injury in the retina.

Animals↗

PubMed1998

The influence of compressive loading on growth of cartilage of the mandibular condyle in vitro.

The purpose of this study was to clarify the change in mandibular condyles under compressive loading. An organ-culture system of fetal rat mandibular condyles was used, and mechanical loading was generated by compressing the gas phase within a closed chamber. After the culture period, with compressive loading, type I collagen and fibronectin were observed in the lower half of the hypertrophic chondrocyte layer in the mandibular condyles; in contrast, without compressive loading, there was no such reaction. The size of the condyle was not increased by compressive loading. These results suggest that intermittent compressive loading could induce type I collagen and fibronectin production by chondrocytes.

Animals↗

PubMed1998