Search PubMed⌕ Search

Biomedical subjects

N Imai

Publications and source records attributed to N Imai.

At least 37 records · Page 2Linked to original sources
PubMed2001

Expression of bone morphogenetic proteins in colon carcinoma with heterotopic ossification.

Here we report the case of a 50-year-old woman with adenocarcinoma of the colon, showing heterotopic ossification. The patient was referred to our hospital for investigation of anemia secondary to occult gastrointestinal blood loss. By colonoscopy, an irregular polypoid mass was found in the ascending colon. A biopsy of the lesion revealed moderately to poorly differentiated adenocarcinoma with heterotopic ossification. A right hemicolectomy was done and revealed areas of heterotopic bone within the tumor, but no ossification was evident in the metastatic lesions within the mesenteric lymph nodes. The formation of heterotopic bone in gastrointestinal tumors is rare and its exact mechanism is unknown. Immunohistochemical localization of bone morphogenetic proteins (BMP), known to be primary inducers of new bone formation, was determined. BMP-5 and -6 were prominent in the cytoplasm of tumor cells, and they stained weakly in osteoblast-like cells adjacent to newly formed bone. Cytoplasmic staining for BMP-2 and -4 was weak in tumor cells, osteoblast-like cells, and stromal fibroblast cells. BMP may play an important role in heterotopic ossification in colon adenocarcinoma.

Adenocarcinoma↗
PubMed2001

Expression of osteopontin in gentamicin-induced acute tubular necrosis and its recovery process.

BACKGROUND: There is controversy regarding the exact localization and roles of osteopontin (OPN), a multipotential chemokine, in renal injury. There is little information on the expression and role of OPN in gentamicin-induced acute tubular necrosis (ATN) and its recovery process. METHODS: A severe ATN model was made using male Wistar rats by injecting gentamicin (150 mg/kg/day) for five days and limiting the provision of water. The expression and localization of OPN mRNA and protein, ED1 as a macrophage marker, proliferating cellular nuclear antigen (PCNA), CD44 as an OPN receptor, megalin as a proximal tubule marker, and their relationships to each other were examined from the early tubular necrotic period to the late recovery period by Northern blotting, in situ hybridization, and double immunohistochemical staining. RESULTS: In the gentamicin group, OPN mRNA and protein were expressed in only the PCNA-positive proliferating cortical distal tubules, not in the necrotic proximal tubules, until day 6 after the first administration, but were found markedly in PCNA-positive regenerative proximal and distal tubules on days 10, 15, and 30. The localization of PCNA-positive cells was almost always accompanied with the up-regulated expression of OPN using quantitative analysis (P < 0.01). CD44 expression was markedly up-regulated in the renal cortical tubular epithelium from days 6 to 30. In the control group, no expression of OPN and CD44 in the cortical area was found throughout the experimental period. CONCLUSIONS: These results suggested that OPN is related to the proliferation and regeneration of tubular epithelial cells after tubular damage.

Animals↗
PubMed2001

Novel glomerular lipoprotein deposits associated with apolipoprotein E2 homozygosity.

BACKGROUND: Hyperlipoproteinemia is occasionally associated with severe glomerular injury caused by abnormal accumulation of lipid in glomeruli, which occurs in conditions such as lipoprotein glomerulopathy (LPG). This study investigates the cases of two siblings with homozygous apolipoprotein (apo) E2 who show unique histologic features, massive proteinuria, and dysbetalipoproteinemia. METHODS: Histologic studies were performed using renal biopsy specimens. Plasma lipoproteins were extensively characterized. The exons of the apo E genes were sequenced to avoid missing any mutations. RESULTS: Histologically, the siblings' condition resembled LPG by light microscopy studies. Electron microscopy studies revealed large lipoid deposits in the paramesangium, subendothelium, and subepithelium of the glomeruli, which were different from LPG in terms of not forming the layered structure resembling a fingerprint even in large lipoprotein thrombi, and mesangial foam cells. Immunohistochemically, the lipoid deposits contained apo E and apo B. These patients did not have either diabetic nephropathy or other known forms of glomerulonephritis. The sequence of exons of the apo E genes revealed homozygosity for apo E2 in both cases. CONCLUSION: The extensive lipoprotein deposition in glomeruli, which resembles LPG, can also occur in apo E2 homozygous individuals, but in a distinct fashion. Because the two cases were siblings, they may have other shared alleles, in addition to the apo E2 allele, that negatively affect processing of lipoproteins and lead to abnormal accumulation of lipoprotein deposits in glomeruli.

Amino Acid Sequence↗
PubMed2001

Membranoproliferative glomerulonephritis associated with hypocomplementemic urticarial vasculitis after complete remission of membranous nephropathy.

A 49-year-old-man developed proteinuria in 1978. He was diagnosed as having membranous nephropathy by renal biopsy and was treated with prednisolone. The proteinuria disappeared completely and the treatment was stopped. In 1995, after complete remission, he developed nephrotic syndrome with chronic urticaria and hypocomplementemia. Renal biopsy revealed membranoproliferative glomerulonephritis (type I) and skin biopsy showed leukocytoclastic vasculitis, which was compatible with hypocomplementemic vasculitis syndrome. Steroid therapy was very effective.

Anti-Inflammatory Agents↗
PubMed2001

Determination of optimal blood pressure for patients with IgA nephropathy based on renal histology.

To evaluate the optimal BP control for patients with IgA nephropathy (IgAN) based on the histologic severity of the nephropathy and the degree of renal dysfunction. We analyzed 332 consecutive renal biopsy specimens and clinical data from patients with IgAN. Patients were divided into three groups based on their BP at the time of biopsy: an optimal BP (SBP<120 mmHg and DBP<80 mmHg), a hypertensive BP (SBP > or = 140 mmHg and/or DBP > or = 90 mmHg), and an intermediate BP group. Each biopsy specimen was evaluated for mesangial proliferation, degree of sclerosis and/or hyalinosis of the arterioles and the interlobular artery using a semiquantitative method. Creatinine clearance and the percentage of sclerosed glomeruli were also determined. Both the degree of renal dysfunction and the histologic changes correlated significantly with BP, even in patients with a BP <140/90 mmHg. The patients with an optimal BP at the time of biopsy had significantly less histologic damage with respect to mesangial proliferation and vessel changes than those with an intermediate or hypertensive BP. In the patients with a hypertensive BP, the percentage of sclerotic glomeruli was significantly higher and the creatinine clearance was significantly lower. The optimal BP proposed by the WHO in 1999 prevents histologic evidence of renal damage for patients with IgAN.

Adult↗
PubMed2001

[A case of silicosis with MPO-ANCA-associated glomerulonephritis and alveolar hemorrhage].

A 63-year-old man was referred to our hospital for rapid deterioration of his renal function. He had worked as a metal founder for more than 40 years, and had been diagnosed as having silicosis. Laboratory data on admission showed severe anemia, thrombocytopenia, and end-stage renal failure (BUN 88.8 mg/dl, serum creatinine 9.0 mg/dl). Myeloperoxidase anti-neutrophil cytoplasmic antibody(MPO-ANCA) was also detected in his sera. On the next day after admission, he complained of sudden dyspnea and hemoptysis. Mechanical ventilation with pure oxygen was insufficient to improve hypoxia without concomitant use of percutaneous cardio-pulmonary support(PCPS) and continuous hemofiltration(CHF). We diagnosed his condition as MPO-ANCA-associated rapidly progressive glomerulonephritis with diffuse alveolar hemorrhage. Treatment with plasmapheresis, pulse methylprednisolone and pulse cyclophosphamide effectively improved his hemoptysis as well as chest X-ray findings and blood gas analysis. However on his later clinical course, he was complicated with superimposed complex infection and passed away. Autopsy findings showed crescentic glomerulonephritis in the kidneys and silica nodules in the lungs. Recently it has been postulated that some relationship exists between ANCA-associated(especially MPO-ANCA-associated) glomerulonephritis and silica exposure. The reported cases of glomerulonephritis in the patients with silica exposure showed a rapidly progressive clinical course and pauci-immune necrotizing crescentic glomerulonephritis in their histology. Gregorini et al. reported that 12 of 37 (32%) male patients with RPGN had either silicosis or significant silica exposure, and 7 of 8 patients examined were ANCA-positive(6 of 7 were MPO-ANCA-positive). Therefore silica seems to cause glomerulonephritis by disrupting the immune response. Including this case mentioned above, we have experienced 10 cases of MPO-ANCA-associated glomerulonephritis, at least 3 cases out of which had suffered from silicosis in the past(30%). These results indicate that silicosis should be considered a relevant pathogen of MPO-ANCA-associated glomerulonephritis beyond the race.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed2001

Induction of cellular immune responses to tumor cells and peptides in colorectal cancer patients by vaccination with SART3 peptides.

The tumor-rejection antigen SART3 possesses two antigenic epitopes (SART3(109-118) and SART3(315-323)) capable of inducing HLA-A24-restricted and tumor-specific CTLs. To determine its safety and ability to generate antitumor immune responses, 12 patients with advanced colorectal cancer were administered s.c. vaccinations of these peptides. No severe adverse events were associated with the vaccinations. Significant levels of increased cellular immune responses to both HLA-A24+ colon cancer cells and the vaccinated peptide were observed in the postvaccination peripheral blood mononuclear cells in 7 of 11 and 7 of 10 patients tested, respectively, and the higher responses were observed in those patients vaccinated with the highest dose (3 mg/injection) of the peptides. These results encourage further development of SART3 peptide vaccine for colorectal cancer patients.

Adult↗
PubMed2000

Identification and characterization of three novel beta 1,3-N-acetylglucosaminyltransferases structurally related to the beta 1,3-galactosyltransferase family.

We have isolated three types of cDNAs encoding novel beta1,3-N-acetylglucosaminyltransferases (designated beta3Gn-T2, -T3, and -T4) from human gastric mucosa and the neuroblastoma cell line SK-N-MC. These enzymes are predicted to be type 2 transmembrane proteins of 397, 372, and 378 amino acids, respectively. They share motifs conserved among members of the beta1,3-galactosyltransferase family and a beta1,3-N-acetylglucosaminyltransferase (designated beta3Gn-T1), but show no structural similarity to another type of beta1,3-N-acetylglucosaminyltransferase (iGnT). Each of the enzymes expressed by insect cells as a secreted protein fused to the FLAG peptide showed beta1,3-N-acetylglucosaminyltransferase activity for type 2 oligosaccharides but not beta1,3-galactosyltransferase activity. These enzymes exhibited different substrate specificity. Transfection of Namalwa KJM-1 cells with beta3Gn-T2, -T3, or -T4 cDNA led to an increase in poly-N-acetyllactosamines recognized by an anti-i-antigen antibody or specific lectins. The expression profiles of these beta3Gn-Ts were different among 35 human tissues. beta3Gn-T2 was ubiquitously expressed, whereas expression of beta3Gn-T3 and -T4 was relatively restricted. beta3Gn-T3 was expressed in colon, jejunum, stomach, esophagus, placenta, and trachea. beta3Gn-T4 was mainly expressed in brain. These results have revealed that several beta1,3-N-acetylglucosaminyltransferases form a family with structural similarity to the beta1,3-galactosyltransferase family. Considering the differences in substrate specificity and distribution, each beta1,3-N-acetylglucosaminyltransferase may play different roles.

Amino Acid Sequence↗
PubMed2000

N(G)-monomethyl-L-arginine inhibits erythropoietin gene expression by stimulating GATA-2.

N(G)-monomethyl-L-arginine (L-NMMA) has been reported to be elevated in uremic patients. Based on the hypothesis that the pathogenesis of the anemia of renal disease might be due to the perturbation of transcription factors of the erythropoietin (Epo) gene by L-NMMA, the present study was designed to investigate the effect of L-NMMA on Epo gene expression through the GATA transcription factor. L-NMMA caused decreased levels of NO, cyclic guanosine monophosphate (cGMP), and Epo protein in Hep3B cells. L-NAME (analogue of L-NMMA) also inhibited Epo production in anemic mice. Transfection of the Epo promoter-luciferase gene into Hep3B cells revealed that L-NMMA inhibited the Epo promoter activity. However, L-NMMA did not inhibit the Epo promoter activity when mutated Epo promoter (GATA to TATA) was transfected, and L-NMMA did not affect the enhancer activity. Electrophoretic mobility shift assays demonstrated the stimulation of GATA binding activity by L-NMMA. However, L-NMMA had no effect on the binding activity of hepatic nuclear factor-4, COUP-TF1, hypoxia-inducing factor-1, or NF-kappaB. Furthermore, cGMP inhibited the L-NMMA-induced GATA binding activity. L-NMMA also increased GATA-2 messenger RNA expression. These results demonstrate that L-NMMA suppresses Epo gene expression by up-regulation of the GATA transcription factor and support the hypothesis that L-NMMA is one of the candidate substances that underlie the pathogenesis of renal anemia. (Blood. 2000;96:1716-1722)

Animals↗
PubMed2000

Effects of portal-systemic shunt following 90% partial hepatectomy in rats.

We studied the effects of portal-systemic shunt after massive hepatectomy. Male Wistar rats were divided into two groups: one group underwent laparotomy alone (C group) and in the other group a portal-systemic shunt was placed through laparotomy (S group). After 90% hepatectomy was performed, 3-day and 1-week survival rates and histopathology were examined, and hepatic hemodynamics during the early stage after hepatectomy were measured using dye-containing microspheres. The 3-day survival rate in the S group was significantly higher, and the 1-week survival rate was slightly higher, than those in C group. Sinusoidal dilation 7 days after hepatectomy in the S group was significantly milder than that in the C group. Fatty degeneration of hepatocytes in the S group was significantly milder than that in the C group. With respect to hepatic hemodynamics during the early stage after hepatectomy, the rate of shunt (26.3%) in the S group was significantly higher than that (9.5%) in the C group. Portal pressure, total hepatic blood flow, and total hepatic blood flow per gram of liver in the S group were significantly lower than those in the C group. These results suggest that approximately 26% shunt after 90% hepatectomy in rats increases the early survival rate and improves histological changes in surviving rats 7 days after resection.

Animals↗
PubMed2000

Ultrastructural characteristics of diabetic nephropathy.

Diabetic nephropathy is a major cause of chronic renal failure in Japan, and the prevalence rate has markedly increased during the past decade. Diabetic nephropathy shows various specific histological changes not only in glomeruli but also in the interstitial region. Nodular, diffuse, and exudative lesions, so-called diabetic glomerulosclerosis, are well known as glomerular lesions. At first, they were historically evaluated only by light microscopy, and thus which components of the glomeruli were modified was not sufficiently clear. Subsequent electron microscopic studies clarified that the expansion of the mesangial matrix was the true form of nodular and diffuse lesions, and that insudated serum substance was the real appearance of an exudative lesion. Interstitial lesions also exhibit specific features in diabetic nephropathy. In electron microscopic studies, it was proved that the size of mitochondria and thickness of the tubular basement membrane were increased in diabetic nephropathy. In this review, we introduce typical electron microscopic findings in diabetic nephropathy and recent opinions on the progression of diabetic nephropathy.

Diabetic Nephropathies↗
PubMed2000

Involvement of eosinophils in the early-phase allergic reaction in a guinea pig rhinitis model.

BACKGROUND: Eosinophils are found in the nasal lavage fluid (NLF) and nasal biopsies of patients with allergic rhinitis after a nasal antigen challenge, and associated not only with a late-phase allergic reaction (LPR) but also an early phase allergic reaction (EPR). Numerous studies have been carried out to clarify the participation of eosinophils in LPR or airway hyperresponsiveness. However, there has been no published report describing in detail the role of eosinophils during EPR. To better understand the involvement of eosinophils in EPR, we studied the effects of repeated antigen challenges on nasal airway responsiveness and eosinophilic inflammation in EPR using a guinea pig rhinitis model. METHODS: Nasal airway responsiveness was measured as the nasal airway resistance (NAR) after nasal antigen provocation. Eosinophilic inflammation during EPR was assessed by nasal lavage and histopathological examination using two groups of animals: those in group 1 were subjected to a sensitization pretreatment only, and those in group 2 were subjected to a pretreatment of sensitization followed by repeated nasal challenges. RESULTS: Repeated antigen challenges induced nasal hyperresponsiveness as indicated by a decrease in the antigen provocation dose and a significant increase in NAR. Furthermore, significant increases in eosinophil counts, eosinophil peroxidase (EPO) activity and protein content in NLF during EPR were observed following antigen provocation in group 2. There were significant correlations between the levels of these parameters, and albumin was the most prevalent of the proteins in NLF. Histopathological examination showed that the degree of eosinophil infiltration into the lamina propria of the nasal mucosa of the animals in group 2 was significantly and apparently higher than in group 1. Particularly, epithelial disruption and mucosal edema were significantly elevated after antigen provocation in group 2. CONCLUSIONS: These results suggest that chronic eosinophil accumulation is induced by repeated antigen challenges in the nasal tissue, and that once antigen provocation occurs, eosinophils in the tissue are activated and responsible for the amplification of EPR such as vascular permeability and mucosal edema.

Animals↗
PubMed2000

Treatment of membranoproliferative glomerulonephritis associated with hepatitis C virus infection. Niigata Research Group of Glomerulonephritis and Nephrotic Syndrome.

OBJECTIVE: Interferon has been used as a new therapeutic agent for glomerulonephritis since a manifest relationship between membranoproliferative glomerulonephritis (MPGN) and hepatitis C virus (HCV) infection was documented. However, several side effects and rebound phenomenon have been significant problems. We retrospectively evaluated the therapeutic effect and safety of the standard treatment with steroids and/or immunosuppressive agents for MPGN patients with an HCV infection. METHODS: Remission and renal survival rates as well as clinical and histological data were compared between MPGN groups with or without an HCV infection. In addition, the hepatic function was followed-up after the treatment. PATIENTS: The subjects were 42 biopsy proven MPGN patients. Seven were positive for an HCV infection. Secondary causes of MPGN excluding an HCV infection were omitted. Most patients were treated with steroids and/or immunosuppressive agents. RESULTS: The mean age of the MPGN patients with an HCV infection was significantly higher than that of those without an HCV infection. The renal function and the interstitial change of the former group were significantly worse than those of the latter. Nevertheless, remission and renal survival rates were not significantly different between the two groups. None in the HCV positive MPGN group showed an impairment of hepatic function during the clinical course. However, 2 subjects died from severe pneumonia during the treatment. CONCLUSION: The standard treatment with steroids and/or immunosuppressive agents did not reveal a statistical difference in the therapeutic efficacy between MPGN patients with or without an HCV infection. However, some in the former group showed a poor prognosis.

Adult↗
PubMed1999

Chamber-specific regulation of heme oxygenase-1 (heat shock protein 32) in right-sided congestive heart failure.

Heme oxygenase (HO)-1 is a stress protein (HSP 32) and, together with HO-2, catalyses oxidation of the heme molecule to generate carbon monoxide, a gas with vasodilatory properties, and bilirubin, an antioxidant. Right-sided heart failure (RHF) resulted in a two-fold increase in the HO-1 transcript (;1.8 kb) in the right ventricle (RV) of RHF dogs compared to that of controls. In contrast, the left ventricle showed no increase in HO-1 mRNA in RHF. The change in HO was unique to HO-1, because neither the HO-2 transcripts (;1.3 and 1.9 kb) nor the HSP 70 mRNA was altered in either ventricle. This increase in HO-1 mRNA in RV was accompanied by a two-fold increase in immunoreactive HO-1 protein, as judged by Western blot analysis, as well as by a significant increase in cGMP levels. There was, however, no significant increase in RV total nitric oxide synthase activity in RHF. Furthermore, since norepinephrine infusion also increased HO-1 transcript and protein levels, the HO-1 system probably was induced in RHF by the increased interstitial norepinephrine levels known to occur in failing myocardium. This differential regulation and induction of HO-1 gene in the failing ventricle might be one of the defense mechanisms by which the heart attempts to protect from stress caused by congestive heart failure.

Animals↗
PubMed1999

Cloning and sequence analysis of hydroxyquinol 1,2-dioxygenase gene in 2,4,6-trichlorophenol-degrading Ralstonia pickettii DTP0602 and characterization of its product.

A gene encoding hydroxyquinol 1,2-dioxygenase was cloned from 2,4,6-trichlorophenol-degrading Ralstonia (Pseudomonas) pickettii strain DTP0602. Cell-free extracts of Escherichia coli containing a cloned 1.4-kb StuI-XhoI DNA fragment of R. pickettii DTP0602 hydroxyquinol 1,2-dioxygenase converted hydroxyquinol into maleylacetate and also degraded 6-chlorohydroxyquinol. The 1.4-kb DNA fragment contained one open reading frame (designated hadC) composed of 948 nucleotides. The molecular mass of 34,591 deduced from the gene product (HadC) was in agreement with the size (35 kDa) of the purified HadC protein determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amino acid sequence of HadC exhibited high homology to that of the hydroxyquinol 1,2-dioxygenase of 2,4,5-trichlorophenoxyacetic acid-degrading Burkholderia cepacia AC1100 (Daubaras, D. L. et al., Appl. Environ. Microbiol., 61, 1279-1289, 1995). The active enzyme had a molecular mass of 68 kDa, suggesting that it is functional as a homodimer. The enzyme also catalyzed the oxidation of pyrogallol and 3-methylcatechol, possible intermediates in the degradation of 2,4,6-trichlorophenol, in addition to 6-chlorohydroxyquinol and hydroxyquinol. The dioxygenase catalyzed both ortho- and meta-cleavage of 3-methylcatechol.

Journal Article↗
PubMed1999

Molecular cloning of mouse p47, a second group mammalian RuvB DNA helicase-like protein: homology with those from human and Saccharomyces cerevisiae.

A 47k protein (p47) in a high-salt buffer extract of a rat liver nuclear matrix fraction was purified by means of a wheat germ agglutinin affinity column, reversed phase HPLC, and SDS-PAGE, and partial amino acid sequences were analyzed. Based on these sequences, the mouse cDNA of the protein was cloned and sequenced, and its amino acid sequence was deduced. Mouse p47 consists of 463 amino acid residues with a molecular weight of 51,112. The amino acid sequences of human and Saccharomyces cerevisiae p47s were also deduced from the nucleotide sequences of "expressed sequence tag" fragments and genomic DNA, respectively. These sequences contain helicase motifs and show homology to bacterial RuvB DNA helicases acting in homologous recombination. They also show homology with the putative mammalian helicases p50/TIP49 and RUVBL1. Comparison of the amino acid sequences of p47 group proteins and those of p50/TIP49 group proteins revealed the p47 group proteins to comprise a group distinct from the p50/TIP49 proteins. Ultracentrifugation and gel filtration analyses showed that p47 in the rat liver cytosol fraction exists as large complexes of 697k.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1999

The leukotriene B4 receptor antagonist ONO-4057 inhibits nephrotoxic serum nephritis in WKY rats.

To evaluate the role of leukotriene B4 (LTB4) in glomerulonephritis, this study was conducted to examine whether ONO-4057, an LTB4 receptor antagonist, moderated nephritis caused by the injection of nephrotoxic serum (NTS) into Wistar-Kyoto rats. Rats were given intraperitoneal injections of ONO-4057 or phosphate-buffered saline 24 h before the injection of NTS. These rats subsequently received equal doses of ONO-4057 or phosphate-buffered saline 3 h and 1, 2, 3, 4, 5, and 6 d later. Compared with the control groups, ONO-4057 treatment significantly reduced proteinuria and hematuria, suppressed the glomerular accumulation of monocytes/macrophages, and reduced the formation of crescentic glomeruli in a dose-dependent manner. These results suggest that LTB4 is responsible for the crescentic formations and renal dysfunction associated with NTS nephritis. The LTB4 receptor antagonist ONO-4057 may thus be beneficial in the treatment of crescentic glomerulonephritis.

Animals↗