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Biomedical subjects

S Amano

Publications and source records attributed to S Amano.

At least 109 records · Page 6Linked to original sources
PubMed1999

[Long-term outcome of topical cyclosporine treatment following penetrating keratoplasty].

PURPOSE: To evaluate the long-term outcome of 2% topical cyclosporine A (CsA) treatment as an adjunct to topical corticosteroid in 86 eyes after penetrating keratoplasty (PK). MATERIAL AND METHODS: The subjects were 86 eyes of 83 patients who had undergone PK and received topical CsA treatments. Ninety-seven eyes of 95 patients who had undergone PK and received similar postoperative treatments except for topical CsA treatments served as control: The clinical outcome of PK was evaluated by rates of graft survival and rejection-free graft survival using Kaplan-Meier's method and compared with the log-rank test. The patients were subdivided into high-risk and low-risk groups. The high-risk patients were those who had corneal vascularization in 2 or more quadrants of the cornea preoperatively or who received regrafting. All other patients were assigned to the low-risk group. Thirty-six eyes of the CsA group and 50 eyes of the control group were high-risk cases. RESULTS: In the high-risk patients, the rejection-free graft survival rate was 69.7% in the CsA group and 45.4% in the control group (p = 0.030). However, there was no significant difference in the graft survival rate between the two groups. In the low-risk patients, there was no significant difference in the rates of rejection-free graft survival and graft survival between the CsA and the control group. CONCLUSION: 2% topical cyclosporine is effective in reducing the risk of allograft rejection in high-risk recipients.

Administration, Topical↗
PubMed1999

Constitutive expression of VEGF, VEGFR-1, and VEGFR-2 in normal eyes.

PURPOSE: The expression of vascular endothelial growth factor (VEGF) and its high-affinity receptors VEGFR-1 and VEGFR-2 was investigated in normal eyes. METHODS: Monkey and rat eyes were surgically removed in animals under deep anesthesia and immediately prepared for study. Ocular VEGF, VEGFR-1, and VEGFR-2 expression was studied using a combination of in situ hybridization, northern blot analysis, immunohistochemistry, immunoassay, and reverse transcription-polymerase chain reaction. RESULTS: Steady state VEGF mRNA levels were detected in the normal vascularized ocular tissues of the monkey: the conjunctiva, iris, retina, and the choroid-retinal pigment epithelial complex. VEGF121 and VEGF165 were the major isoforms identified. VEGF protein was detected in the conjunctiva, retina, and the choroid-retinal pigment epithelial complex. Retinal VEGF mRNA localized to the ganglion, inner nuclear, and retinal pigment epithelial cell layers. VEGF protein localized to these same layers and to the cones of monkey retina. VEGFR-1 and VEGFR-2 mRNAs were detected in normal monkey iris, retina, and the choroid-retinal pigment epithelial complex. In both monkey and rat eyes, VEGFR-1 and VEGFR-2 mRNAs were localized to the inner nuclear layer of the retina. CONCLUSIONS: VEGF, VEGFR-1, and VEGFR-2 are constitutively expressed in the vascularized tissues of normal eyes.

Animals↗
PubMed1999

Insulin-induced vascular endothelial growth factor expression in retina.

PURPOSE: Clinical studies have demonstrated that intensive insulin therapy causes a transient worsening of retinopathy. The mechanisms underlying the initial insulin-induced deterioration of retinal status in patients with diabetes remain unknown. Vascular endothelial growth factor (VEGF) is known to be operative in the pathogenesis of diabetic retinopathy. The current study was conducted to characterize the effect of insulin on retinal VEGF gene expression in vitro and in vivo. METHODS: The effect of insulin on VEGF expression in vivo was examined by in situ hybridization studies of rat retinal VEGF transcripts. To examine the mechanisms by which insulin regulates VEGF expression, human retinal pigment epithelial (RPE) cells were exposed to insulin, and VEGF mRNA levels were quantified with RNase protection assays (RPAs). Conditioned media from insulin-treated RPE cells were assayed for VEGF protein and capillary endothelial cell proliferation. The capacity of insulin to stimulate the VEGF promoter linked to a luciferase reporter gene was characterized in transient transfection assays. RESULTS: Insulin increased VEGF mRNA levels in the ganglion, inner nuclear, and RPE cell layers. In vitro, insulin increased VEGF mRNA levels in human RPE cells and enhanced VEGF promoter activity without affecting transcript stability. Insulin treatment also increased VEGF protein levels in conditioned RPE cell media in a dose-dependent manner with a median effective concentration of 5 nM. The insulin-conditioned RPE cell media stimulated capillary endothelial cell proliferation, an effect that was completely blocked by anti-VEGF neutralizing antibody. CONCLUSIONS: Insulin increases VEGF mRNA and secreted protein levels in RPE cells through enhanced transcription of the VEGF gene. Intensive insulin therapy may cause a transient worsening of retinopathy in patients with diabetes through increased retinal VEGF gene expression.

Animals↗
PubMed1999

[A case of preoperatively diagnosed primary pulmonary leiomyosarcoma].

A 29-year-old woman had been suffering from right back pain for 3 months. Chronic pulmonary thromboembolism was suspected and she was referred to our hospital. She presented with no risk factors for thromboembolism, and during the previous 6 months had lost 4 kg in body weight. Chest radiography showed nodular shadows in the lower field of the right lung. Contrast-enhanced computed tomography demonstrated a filling defect in the right pulmonary artery and nodular lesions in the lower field of the right lung, which were considered to be signs of pulmonary infarction. Absence of perfusion into the right lung was demonstrated by a perfusion scan. Right heart catheterization showed normal pressure in the pulmonary arteries, and pulmonary angiography showed an abrupt cutoff of the right pulmonary artery, which was similar to the finding of pulmonary thromboembolism. A transvenous catheter suction biopsy was performed in the right pulmonary artery and the histopathologic findings yielded a diagnosis of leiomyosarcoma. The patient underwent surgical resection under total cardiopulmonary bypass. A large tumor completely filled the right main pulmonary artery and invaded the posterior wall of the pulmonary trunk close to the left main pulmonary artery. Primary pulmonary leiomyosarcoma is a rare tumor and its prognosis is very poor. Radical surgical resection is the only effective treatment, but early diagnosis is very difficult. Transvenous catheter suction biopsy is a useful procedure for the early diagnosis of pulmonary artery sarcoma.

Adult↗
PubMed1998

Purification of native p94, a muscle-specific calpain, and characterization of its autolysis.

p94, a skeletal muscle-specific calpain, has attracted much attention because its gene is responsible for limb-girdle muscular dystrophy type 2A. p94, however, has not been characterized at the protein and enzyme levels, owing to its very rapid autolysis. In the present study, a purification procedure for p94 was first established by using a recombinant inactive p94 expressed in COS cells in which the active site cysteine residue was changed to serine [p94(C129S)]. The isolation of native p94 from rabbit skeletal muscle by the established method with conventional procedures was extremely difficult because p94 became highly unstable in a crude extract on the addition of NaCl for separation. Purification of native p94 was possible with an antibody-affinity column but only as an inactive enzyme; p94(C129S) was purified as a homodimer. Characterization of p94, especially autolysis, was performed with partly purified native p94 and p94(C129S). The autolysis of p94, which consisted at least partly of an intermolecular reaction, proceeded in three consecutive steps; 60 and 58 kDa fragments were produced as intermediates before a stable 55 kDa fragment appeared. Autolysis of p94 was regarded as a degradative step rather than for the activation of the enzyme. All the autolysis cleavage sites were located in the p94-specific insertion sequence 1 region, which explains why p94 is unstable compared with the other calpains. The autolysis sites in p94 clearly showed a different specificity relative to the autolytic and proteolytic cleavage sites of the ubiquitous mu- and m-calpains, in its preference for residues at the P3 to P1' sites, indicating a distinct substrate specificity and function for the muscle enzyme.

Amino Acid Sequence↗
PubMed1998

Isochronous storage ring of the New SUBARU project.

The aims of the New SUBARU project are to promote industrial applications in the VUV and soft X-ray region and to develop research and development towards new light sources. The main facility of the New SUBARU project is the 1.5 GeV electron storage ring which is under construction at the SPring-8 site in Harima Science Garden City, Japan. The storage ring is quasi-isochronous and has variable momentum dispersion for the deep study of beam dynamics in very short bunches.

Journal Article↗
PubMed1998

Normal developing rat brain expresses a platelet-derived growth factor B chain (c-sis) mRNA truncated at the 5' end.

The 5' untranslated sequence (5' UTS) of platelet-derived growth factor B (PDGF-B/c-sis) mRNA is highly preserved through evolution, and inhibits translation of downstream coding sequences. In this study, using Northern analysis we identified two PDGF-B/c-sis mRNAs (3.5 kb and 2.6 kb) expressed in normal developing rat brain. In contrast to the constitutive expression of 3.5 kb mRNA, the expression of 2.6 kb mRNA increased markedly in accordance with those stages of brain development at which we had previously demonstrated an increased immunoreactivity for PDGF-B/c-SIS in neurons (Sasahara et al., 1992). By PCR cloning and the RNase protection assay, we determined the complete sequence of rat PDGF-B/c-sis, and found that the 2.6 kb transcript was a form of the 3.5 kb message truncated at the 5' end, and that the predominant 2.6 kb mRNA commenced 15 nt upstream of the signal peptide. Accordingly, it is suggested that the truncation of 5' UTS contributes to the expression of PDGF-B/c-SIS protein in the CNS. Lack of translational inhibitory 5' UTS of PDGF-B/c-sis transcript and resultant efficient protein translation have been reported in only a few transformed cells and cultured umbilical vein endothelial cells. We have extended this knowledge to the developing rat brain, and suggest that a similar mechanism could operate widely in non-transformed tissue in vivo.

Animals↗
PubMed1998

Advanced glycation end products increase retinal vascular endothelial growth factor expression.

Advanced glycation end products (AGEs) are linked with the development of diabetic retinopathy; however, the pathogenic mechanisms are poorly defined. Vascular endothelial growth factor (VEGF) levels are increased in ischemic and nonischemic diabetic retina, and VEGF is required for the development of retinal and iris neovascularization. Moreover, VEGF alone can induce much of the concomitant pathology of diabetic retinopathy. In this study, we found that AGEs increased VEGF mRNA levels in the ganglion, inner nuclear, and retinal pigment epithelial (RPE) cell layers of the rat retina. In vitro, AGEs increased VEGF mRNA and secreted protein in human RPE and bovine vascular smooth muscle cells. The AGE-induced increases in VEGF expression were dose- and time-dependent, inhibited by antioxidants, and additive with hypoxia. Use of an anti-VEGF antibody blocked the capillary endothelial cell proliferation induced by the conditioned media of AGE-treated cells. AGEs may participate in the pathogenesis of diabetic retinopathy through their ability to increase retinal VEGF gene expression.

Animals↗
PubMed1998

Expression of heparin-binding epidermal growth factor-like growth factor in rat brain.

According to a recent report, messenger RNA coding for a member of the epidermal growth factor (EGF) family, heparin-binding EGF-like growth factor (HB-EGF), is expressed in the central nervous system (CNS). To obtain information about the role of HB-EGF in the brain, we carried out Northern analysis, in situ hybridization, and immunohistochemical studies evaluating the distribution and amounts of the growth factor using cDNA HB-EGF probes and an antibody raised against synthetic HB-EGF propeptide. Northern analysis revealed transcripts for HB-EGF in all regions of normal rat brain. Immunohistochemically, HB-EGF was demonstrated extensively in neurons at levels varying according to location. HB-EGF mRNA also was detected in neurons, suggesting that the growth factor is produced in these cells. HB-EGF mRNA and immunoreactivity were also demonstrated in interfascicular oligodendrocytes. These findings suggest that HB-EGF is a physiologic ligand for brain EGF receptors, and is likely to be important in neural function.

Animals↗
PubMed1998

Expression of CD44 in rat liver allografts during rejection.

As CD44 is believed to be a homing receptor involved in lymphoid trafficking and inflammatory responses, it is expected to be closely linked to transplant rejection. In this study, the expression of CD44 during liver transplant rejection was compared with the expression of lymphocyte-function associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1), which play an essential role in cell interactions and the initiation of immune responses. Male Brown Norway (BN) and Lewis (LEW) rats were used as donors and recipients, respectively. Orthotopic liver transplantation (OLTX) was done using the cuff technique of Kamada and Calne. Animals were killed on days 3, 5, and 7 after OLTX, and a piece of tissue from each of the liver grafts was obtained. Immunohistochemical staining was used to investigate the expression of CD44, ICAM-1, and LFA-1. CD44 was strongly expressed in portal areas of the rejected liver, and LFA-1 and ICAM-1 were expressed mainly on sinusoids and hepatocytes. These findings indicate that CD44 is closely involved in lymphocyte infiltration, which is dominant in portal areas, and that lymphocyte infiltration during the rejection process may involve a homing mechanism.

Animals↗
PubMed1998

Increased serum concentrations of soluble tumor necrosis factor receptor I in noncachectic and cachectic patients with advanced gastric and colorectal cancer.

The serum levels of soluble tumor necrosis factor receptor I (sTNF-RI) were measured in 74 noncachectic patients including 42 with gastric cancer and 32 with colorectal cancer, as well as in 39 patients with severe cachexia and 15 healthy volunteers. The sTNF-RI levels increased with the advance of disease, being highest in the cachectic patients. The levels were inversely correlated with the serum concentrations of nutritional parameters such as prealbumin, transferrin, retinol binding protein, and the percentages of CD3(+) cells in the peripheral blood lymphocytes, and positively correlated with the serum concentration of immunosuppressive acidic protein (IAP) and soluble interleukin-2 receptors. These findings suggest that sTNF-RI could be an important prognostic factor to predict the advance of gastric and colorectal cancers and deterioration of the patient's nutritional and immune activity.

Antigens, CD↗
PubMed1998

Laminin 5 can promote assembly of the lamina densa in the skin equivalent model.

Skin equivalents were prepared by culturing human keratinocytes on the surface of type I collagen gel contracted by human skin fibroblasts (dermal equivalents) and by raising the gel to an air-liquid interface. A stratified squamous epithelium was formed with a well-differentiated cornified layer at the top of keratinocyte layers within 7 days after plating of the keratinocytes on the dermal equivalents. Although major basement membrane components such as collagens IV and VII and laminin 5 were detected immunohistochemically at the dermal-epidermal junction, a lamina densa was rarely observed by electron microscopy even in 14-day skin equivalents. When laminin 5 (1, 5 or 20 microg/ml) was added to the culture medium on day 7 through day 14, types IV and VII collagens at the dermal-epidermal junction stained more strongly by immunohistochemistry compared with the control. Patches of lamina densa were present along the epidermal-dermal junction, and vesicles containing electron-opaque sheets approximately 0.6 microm in diameter that reacted with anti-collagen IV antibody were also observed in basal keratinocytes in 14-day skin equivalents by electron microscopy. Morphometric analysis showed that the total length of lamina densa along the dermal-epidermal junction as well as in the vesicles increased up to 180%, 230% or 520% of control cultures by the addition of laminin 5 (1, 5 or 20 microg/ml, respectively). These results suggest that laminin 5 accelerates formation of the lamina densa along the dermal-epidermal junction of the skin equivalents, depending on the concentration of laminin 5 supplemented exogenously.

Basement Membrane↗
PubMed1998

Internalization of Mycobacterium bovis Bacillus Calmette-Guérin into osteoblast-like MC3T3-E1 cells and bone resorptive responses of the cells against the infection.

Mycobacterium bovis BCG (BCG) is a live vaccine used worldwide against tuberculosis. However, it has unfavourable side effects such as osteitis or osteomyelitis, and these sometimes lead to vertebral caries in some patients as a result of bone resorption. Osteoblasts might play a role in the bone resorption caused by BCG infection, because they are central cells in bone metabolism. Cultured osteoblast-like cell lines (MC3T3-E1) derived from C57BL mice susceptible to BCG infection cells were infected with BCG at several doses. Interestingly, internalization of BCG-enveloped phagosome-like membrane in osteoblast-like cells were observed by transmission electron microscopy (TEM). Owing to infection, the proliferation and alkaline phosphatase activity of the osteoblast-like cells were reduced in a dose-dependent manner. On the other hand, interleukin (IL)-6 production was considerably enhanced by infection. These results suggest that BCG infects osteoblasts, suppressing their proliferation and differentiation and inducing bone resorption, which may be related to osteitis/osteomyelitis and bone caries caused by BCG infection.

Animals↗
PubMed1998

Use of a gastric juice-based PCR assay to detect Helicobacter pylori infection in culture-negative patients.

A gastric juice-based PCR assay was compared with culture, microscopy, and a rapid urease test with specimens from 114 subjects. The PCR and conventional tests were positive for 76 and 62% of the subjects, respectively. The prevalence of gastroduodenal disease and seropositivity for anti-Helicobacter pylori immunoglobulin G were similarly high among conventional-test-positive and PCR-only-positive subjects compared to all-negative ones. The PCR assay is recommended to confirm the H. pylori status of culture-negative peptic-ulcer patients.

Adult↗
PubMed1998

Requirement for vascular endothelial growth factor in wound- and inflammation-related corneal neovascularization.

PURPOSE: Vascular endothelial growth factor (VEGF) is required for vascular development and for ischemia-related tumor, iris, and retinal neovascularization. The role of VEGF in inflammatory corneal neovascularization is unknown and was investigated in these studies. METHODS: A rat model was used in which removal of the corneal and limbal epithelium resulted in circumferential neovascularization. Corneal VEGF mRNA levels were quantified with ribonuclease protection assays, and VEGF protein was studied in situ using immunohistochemical analysis. Controlled-release pellets containing anti-VEGF antibodies were implanted into the corneal stroma and were used to determine the requirement for VEGF in corneal neovascularization. RESULTS: VEGF mRNA and protein were induced to high levels after corneal injury and were temporally and spatially correlated with inflammation and neovascularization. VEGF immunoreactivity was localized primarily to the inflammatory cells invading the wounded cornea. The specific inhibition of VEGF bioactivity with neutralizing antibodies potently suppressed corneal neovascularization. CONCLUSIONS: These data are the first to demonstrate that VEGF may be required for inflammatory neovascularization of the rat cornea and to identify VEGF as a functional endogenous corneal angiogenic factor.

Animals↗
PubMed1998

Biodistribution studies on L-3-[fluorine-18]fluoro-alpha-methyl tyrosine: a potential tumor-detecting agent.

UNLABELLED: Iodine-123-alpha-methyl tyrosine has proven to be a promising SPECT agent for imaging amino acid uptake in tumors. We developed L-[3-(18)F]-alpha-methyl tyrosine (FMT) for PET studies. The aim of this study was to investigate its potential use as a tumor-detecting agent by using tumor-bearing mice. METHODS: We investigated the biodistribution in normal BALB/C mice and BALB/cA nude mice bearing human rectal cancer cell line (LS180) until 120 min postinjection. FMT tumor uptake at 60 min postinjection in mice with LS180 rectal cancer, RPM11788 B-cell lymphoma and MCF7 mammary cell carcinoma was assessed, and the results were compared with 18F-fluoro-2-deoxy-D-glucose (FDG) tumor uptake. The effect of competitive inhibition of large neutral amino acid transport system using unlabeled L-alanine was also investigated. RESULTS: The amount of FMT in blood fell to 1.05%ID/20 g at 60 min postinjection, whereas that in the pancreas was 15.2%ID/20 g, resulting in a high pancreas-to-blood ratio of 14.5. In other organs, initial uptake peaked at 5 min postinjection and then declined with time. In LS180 tumor-bearing mice, peak FMT uptake in tumor was observed at 60 min postinjection. Tumor-to-blood and tumor-to-muscle ratios ranged from 1.60 to 2.94 and from 2.79 to 3.25 over the 120-min observation period. Tumor uptake of FMT was clearly reduced by inhibition of the amino acid transport system. In mice with LS180 and MCF7 tumors, FMT tumor uptake at 60 min postinjection was significantly higher than FDG tumor uptake, whereas in RPM11788 lymphoma, uptake of FDG was significantly higher than FMT tumor uptake. Tumor-to-blood ratios of FMT in mice with LS180, RPMI1788 and MCF7 tumor at 60 min postinjection were 1.82, 5.88 and 3.56, respectively. CONCLUSION: FMT, like other fluorinated amino acids, may become a promising tumor-detecting agent for PET, assuming that efficient methods of radiosynthesis are developed.

Amino Acids↗
PubMed1998

[Immunohistochemical study of p53, p27 and PCNA expression in esophageal cancer].

We evaluated the clinical significance of p53, p27 and PCNA expressions in esophageal squamous cell carcinomas. Operative specimens obtained from 70 patients with esophageal squamous cell carcinomas were investigated by staining with antibodies against p53, p27 and PCNA. The correlations among p53, p27 and PCNA expression, clinicopathologic factors and prognosis were studied. The expression of p53 was observed in 55.7%, and it did not correlate to histologic classification, growth pattern, and lymphatic invasion. The expression of p27 was observed in 48.6%, and it correlated to lymph node metastasis. The PCNA positive index (PCNA-PI) was high in the p27 negative cases. The p53 positive and p27 negative group revealed the worst survival rate among groups. Therefore, the p27 positive case, often associated with well differentiated carcinoma, tends to have a slower tumor-growth rate and better prognosis. It is suggested that immunohistochemical assessment on the p53 and p27 expressions would be useful to the recognize the malignant potential and differentiation of squamous cell carcinoma of the esophagus.

Aged↗