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Masamichi Ishizaki

Publications and source records attributed to Masamichi Ishizaki.

14 recordsLinked to original sources
PubMed2006

Immunogenicity and antigenicity of allogeneic amniotic epithelial transplants grafted to the cornea, conjunctiva, and anterior chamber.

PURPOSE: To determine the immunogenic characterization of amniotic epithelium (AE), by examining the fate of allogeneic AE grafts heterotopically transplanted in the eye. METHODS: Intact AE from enhanced green fluorescence protein (EGFP) transgenic mice (C57BL/6 background) and wild-type C57BL/6 mice were transplanted onto cornea or conjunctiva, or inserted into the anterior chamber (AC) of normal BALB/c mice, C57BL/6 mice, or BALB/c mice presensitized to donor antigens. For repeated AE transplantation experiments, AE was grafted in the other eye 7 days after the first grafting. Graft fate was assessed clinically and histologically at selected intervals after grafting. Infiltrating inflammatory cells were examined immunohistochemically. Sensitization to alloantigens by AE was assessed by the delayed hypersensitivity (DH) response. RESULTS: In normal recipients, GFP+ cells were absent in EGFP donor-derived AE grafts by day 21 on cornea and by day 7 on conjunctiva. AE grafts implanted in the AC survived for >8 weeks. In presensitized recipients and recipients that underwent repeated AE implantation, graft survival was markedly shorter than in normal recipients. DH was induced at 2 weeks, but failed to be induced at 4 weeks after grafting on cornea or at 8 weeks after grafting on conjunctiva and in the AC of normal recipients. CONCLUSIONS: Fresh allogeneic AE expressed immunogenicity when placed on the ocular surface, although no memory of allospecific DH was acquired. Allogeneic AE is clearly vulnerable to immune rejection in specifically sensitized recipients.

Amnion↗
PubMed2005

Dimethyl 2,2-dichlorovinyl phosphate (DDVP) markedly decreases the expression of perforin, granzyme A and granulysin in human NK-92CI cell line.

Natural killer (NK), lymphokine-activated killer (LAK) and cytotoxic T lymphocyte (CTL) cells kill target cells by the directed release of cytolytic granules that contain perforin, granzymes and granulysin. We previously have found that dimethyl 2,2-dichlorovinyl phosphate (DDVP), an organophosphorus pesticide significantly inhibited NK, LAK and CTL activities via the inhibition of granzyme activity. To further explore the mechanism of organophosphorus pesticide-induced inhibition of cell-mediated cytolysis, we asked here whether organophosphorus pesticides affect the expression of perforin, granzyme and granulysin in NK cells. We used NK-92CI cell, an interleukin-2 (IL-2) independent human NK cell line. We confirmed that NK-92CI cells express CD56 surface marker, perforin, granzyme A and granulysin by flow cytometry and immunofluorescence microscope, and that it is highly cytotoxic to K562 cells in chromium release assay. We found that DDVP significantly decreases the expression of perforin, granzyme A and granulysin in NK-92CI cells in a dose-dependent manner. Immunocytochemical results showed that DDVP significantly decreases perforin, granzyme A and granulysin positive granules in NK-92CI cell, which may be due to the degranulation. We also found that DDVP have a modest, but a significant inhibitory effect on the transcription of mRNA of perforin, granzyme A and granulysin.

Antigens, Differentiation, T-Lymphocyte↗
PubMed2005

Role of bone marrow cells in the healing process of mouse experimental glomerulonephritis.

Recent studies have shown bone marrow (BM) cells to differentiate into a variety of cell types and to thereby participate in the reconstitution of damaged organs. In the present study, we examined the extent to which BM-derived cells are incorporated into glomeruli during recovery from experimentally induced nephritis. To investigate the localization of BM cells in glomeruli, chimeric mice were prepared by transplanting BM cells from green fluorescent protein (GFP) transgenic mice into wild-type mice. Five weeks later, glomerulonephritis was induced by intravenous injection of Habu snake venom. Groups of mice were then killed every few days for 42 d, and harvested kidney samples were subjected to immunohistochemical and immunoelectron microscopic analyses with the aim of detecting the presence of GFP(+) cells within glomeruli. Chimeric animals injected with Habu venom developed proliferative glomerulonephritis within 1-3 d. The lesion gradually subsided and the glomerular structure returned to normal within 42 d. Consistent with the disease course, large numbers of GFP(+) cells were present within glomeruli on d 1-3, but most had disappeared by d 7. Nevertheless, some GFP(+) cells did remain within glomeruli showing mesangial proliferative changes, and were found to express thrombomodulin (TM), a specific endothelial cell marker. These GFP-TM-double-positive cells accounted for a mean of 1.31-2.24% of the total glomerular nuclei from d 7 through d 42, levels that remained stable for at least 12 mo. It thus appears that BM cells can give rise to endothelial cells that participate in the remodeling of glomeruli.

Animals↗
PubMed2005

Occurrence of hyaline droplets in renal biopsy specimens: an ultrastructural study.

Hyaline droplets are apical cytoplasmic vesicles containing an accumulation of electron-dense amorphous materials surrounded by a unit membrane. Hyaline droplets may originate from apical vesicles after conversion to osmotic vesicles and loss of internally lined glycocalyx. They are found in the proximal tubular epithelium in biopsies from patients with renal diseases; however, their biological importance is not well understood. We reviewed ultrastructural pathology records of 140 renal biopsy patients to determine the occurrence and relevance of hyaline droplets. Of the cases, 14 (10%) showed the presence of hyaline droplets in proximal tubular epithelium. The distribution of cases were 8 of the 19 (42%) with minimal change nephritic syndrome, 2 of the 37 (5%) with IgA nephropathy, 2 of the 4 (50%) with membranous glomerulonephropathy, 1 of the 4 (25%) with tubulointerstitial nephritis, and 1 of the 1 (100%) with acute renal failure. The droplets were frequently found in male patients (86%), never in children, and were mostly associated with tubular necrosis (8 of 14 cases; 56%). Many hyaline droplets were observed in the cytoplasm of necrotic proximal tubular epithelial cells, and even when tubular necrosis was not evident, the proximal tubular epithelial cells containing hyaline droplets showed degenerated microvilli and decreased basal interdigitations. These results suggest that hyaline droplets could be one marker of renal tubular necrosis and a sign of functional disorder of protein reabsorption by degenerating proximal tubular epithelium.

Adult↗
PubMed2005

Expression of cochlin in the vestibular organ of rats.

The COCH gene mutated in autosomal dominant sensorineural deafness (DFNA9) encodes cochlin, a major constituent of the inner ear extracellular matrix. Cochlin constitutes 70% of the inner ear protein and cochlin isoforms can be classified into three subgroups, p63s, p44s and p40s. Symptoms of some DFNA9 patients are consistent with those of Ménière's disease. Here, we report the expression of cochlin in the vestibular organ of rats using isoform-specific antibodies that recognize all three isoforms. Cochlin is highly expressed in the stromata of the maculae of otolithic organs and cristae of semicircular canals, and in the channels in the bony labyrinth that transmit the dendritic innervation to the cristae and maculae. Cochlin cannot be detected in the sensory cells, dark cells, nor in the acellular structures, otolithic membrane or in the cupula. These findings support the theory that deposition of acidophilic substance in the inner ear caused by mutation of cochlin can induce a secondary retrograde dendritic degeneration of the vestibular nerves.

Animals↗
PubMed2005

An asymptomatic heterozygous female with fabry disease: implications for enzyme replacement therapy.

We report an asymptomatic female with Fabry disease immunohistochemically diagnosed by renal biopsy. She was initially diagnosed as having nephrotic syndrome, and renal biopsy was performed for pathological diagnosis. The renal specimen revealed non-specific findings (minor glomerular abnormalities) for nephrotic syndrome. Numerous laminated bodies in glomerular epithelial cells in electron microscopic findings and accumulations of ceramidetrihexoside immunohistochemically were observed and she was diagnosed with Fabry disease. However, no other laboratory data or clinical findings supported the diagnosis of Fabry disease. Since the efficacy of recombinant human alpha-galactosidase replacement therapy in this disease has been reported, whether enzyme replacement therapy for subclinical Fabry female patients is indicated or not is an important issue.

Adolescent↗
PubMed2004

Vascular endothelial growth factor165 resolves glomerular inflammation and accelerates glomerular capillary repair in rat anti-glomerular basement membrane glomerulonephritis.

Vascular endothelial growth factor (VEGF) is essential for maintenance of the glomerular capillary network. The present study investigated the effects of VEGF in rats with progressive crescentic glomerulonephritis (GN). Necrotizing and crescentic GN was induced in rats by injection of anti-rat glomerular basement membrane (GBM) antibody. The alterations of glomerular capillaries and glomerular VEGF expression were assessed. In addition, the effects of continuous VEGF165 administration (10 microg/100 g per d) on glomerular capillaries, glomerular inflammation, and the course of crescentic GN were examined. The appropriate timing of VEGF administration in progressive GN also was evaluated. In anti-GBM GN, necrotizing and crescentic glomerular lesions occurred by day 7, and newly formed necrotizing lesions reoccurred by week 3. Expression of VEGF was markedly reduced in necrotizing and crescentic lesions. Capillary repair was impaired after capillary destruction in necrotizing and crescentic glomeruli, which rapidly progressed to sclerotic glomeruli with chronic renal failure. In contrast, in the rats that received VEGF165 administration from day 7, the necrotizing and crescentic lesions recovered and renal function significantly improved in week 4. This was evident by proliferating endothelial cells and glomerular capillary repair. In addition, VEGF administration decreased intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 expression in glomeruli (particularly on endothelial cells), reduced glomerular infiltrating CD8-postive and ED-1-positive cells, and inhibited the newly formed necrotizing lesions. VEGF administration was apparently effective against both the inflammatory and necrotizing glomerular lesions. These results suggest that VEGF administration resolves glomerular inflammation and accelerates glomerular recovery in the progressive necrotizing and crescentic GN. The therapeutic application of VEGF may be clinically useful for severe GN accompanied by extensive glomerular inflammation and endothelial injury.

Animals↗
PubMed2004

Mechanism of transepithelial elimination of elastic fibers in keratoacanthoma.

Transepithelial elimination of elastic fibers is frequently seen in keratoacanthoma. However, the mechanism underlying this elastic fiber transport is not yet fully understood. We investigated the process by comparing the related features of 27 cases of keratoacanthoma, eight cases of squamous cell carcinoma and 11 cases of seborrheic keratosis (control). Microscopically, transepithelial elimination of elastic fibers was specifically observed in keratoacanthomas. Elastic fibers were surrounded by keratoacanthoma cell membrane and were ultrastructurally associated with hemidesmosomes and the basement membrane. Collagen fibrils were also observed within small, membrane-delineated vesicles within cells in the lower layers of the tumor. Also noted was strong expression of matrix metalloproteinase-1, which was detected by immunohistochemical analysis and in situ hybridization. Western blotting showed significantly stronger labeling of matrix metalloproteinase-1 in samples of keratoacanthoma than in normal epidermis. In contrast, squamous cell carcinomas and seborrheic keratosis exhibited none of the aforementioned characteristics. We propose that keratoacanthoma cells entrap, lift and eliminate elastic fibers as they proliferate and keratinize toward the epidermal surface, while simultaneously phagocytosing collagen fibrils. In that regard, matrix metalloproteinase-1 appears to play a key role in the degradation of collagen fibrils.

Adult↗
PubMed2003

Identification of an electron densification of the glomerular basement membrane in renal biopsy specimens.

Ultrastructural examination of renal biopsy specimens is often necessary to establish a diagnosis. We have noted, in some renal biopsies, that normal-appearing glomerular basement membrane (GBM) shows an electron densification. The aim of this study was to describe this phenomenon and assess the degree of its occurrence. We reviewed ultrastructural pathology records of 153 renal biopsy patients with special reference to the careful examination of the electron micrographs. Of these, 28 cases (18%) showed a definite and homogeneous electron densification of normal-appearing GBM in the glomeruli. The pathological diagnosis in these cases was IgA nephropathy in 15, minimal change nephrotic syndrome in 6, interstitial nephritis in 3, membranoproliferative glomerulonephritis in 2, and nephritis of Henoch-Schonlein purpura and membranous nephropathy in 1 case each. In addition, frequent deposition of IgG without C3 in the GBM (86%) and glomerular endothelial cell edema (96%) were observed. No apparent correlation could be ascertained between the presence of the electron densification and pathological diagnosis. It is suggested that electron densification of the GBM may be caused by the penetration of some electron-dense materials into the GBM as a result of an abnormality in the glomerular filtration barrier and that this could be considered as a sign of altered properties of the lamina densa.

Adolescent↗
PubMed2003

Lentivirus-mediated expression of angiostatin efficiently inhibits neovascularization in a murine proliferative retinopathy model.

Ischemic retinal diseases, such as diabetic retinopathy, retinopathy of prematurity, and age-related macular degeneration, are a major cause of blindness worldwide. Angiostatin is an internal peptide fragment of plasminogen that inhibits endothelial proliferation in vitro and tumor growth in vivo. We now demonstrate that HIV vector encoding angiostatin (HIV-angiostatin) can inhibit retinal neovascularization in a mouse model of proliferative retinopathy. Intravitreal injections of HIV-angiostatin led to stable expression of the angiostatin gene in retinal tissue. Retinal neovascularization was histologically quantitated by a masked protocol. Retinal neovascularization in the eye injected with HIV-angiostatin was reduced in 90% (9/10; P=0.025) of animals, compared with the eye injected with phosphate-buffered saline. Reduction of histologically evident neovascular nuclei per 6-microm section averaged 68%, with maximal inhibitory effects of 87%. Neovascularization was not reduced in the eyes injected with HIV vector encoding enhanced green fluorescent protein. This is the first report that HIV-angiostatin can reduce neovascular cell nuclei in a murine proliferative retinopathy model. These data suggest that the anti-angiogenic activity of angiostatin has therapeutic potential for the treatment of retinal neovascularization.

Angiostatins↗
PubMed2002

Peritubular capillary regression during the progression of experimental obstructive nephropathy.

Injury to the renal microvasculature may be a major factor contributing to the progression of renal disease. Although severe disruption of peritubular capillaries (PTC) could lead to marked tubulointerstitial scarring, elucidation of that process remains incomplete. This study investigated the morphologic changes in PTC and their likely regulation by vascular endothelial growth factor (VEGF) during the progression of tubulointerstitial injuries. Unilateral ureteral obstruction was induced in Wistar rats by ligation of the left ureter, and the kidneys were then collected at selected times. PTC lumina and the expression of VEGF and its receptor Flk-1 were immunohistochemically detected. Morphologic changes in PTC endothelial cells were examined by using Ki67 staining, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling, and electron-microscopic studies. In the first week of the disease period, immunohistochemical labeling of tubular VEGF intensified, with accompanying deformation and dilation of adjacent thrombomodulin (TM)-positive PTC lumina; an angiogenic response of endothelial cells was demonstrated with Ki67 and TM double-staining. During the subsequent 2 wk, tubular VEGF labeling decreased until it was virtually absent, an effect confirmed by Western blotting. Concomitantly, labeling of the VEGF receptor Flk-1 in PTC endothelial cells decreased and PTC lumina began to regress, demonstrating endothelial cell apoptosis (as detected in terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling and electron-microscopic studies). By the end of week 4, the numbers of TM-positive PTC lumina were significantly decreased in areas of marked tubulointerstitial scarring. These results suggest that PTC regression, involving an early, unsustained, angiogenic response followed by progressive endothelial cell apoptosis, could be a potential factor contributing to tubulointerstitial scarring in this unilateral ureteral obstruction model.

Animals↗
PubMed2002

Wound healing involves induction of cyclooxygenase-2 expression in rat skin.

Cyclooxygenase (COX), an enzyme essential for prostaglandin biosynthesis, has two isoforms, COX-1 and -2. We investigated temporal and spatial changes in localization of these two COX proteins and mRNAs after excisional injury in rat skin. We also quantified the expression of these proteins and studied the effects of a specific COX-2 inhibitor on healing. Immunohistochemistry and in situ hybridization respectively indicated that the COX-2 protein and mRNA were expressed mainly within the basal layer of the epidermis, peripheral cells in the outer root sheath of hair follicles, and fibroblast-like cells and capillaries near epidermal wound edges. Much less intense expression was observed in normal skin than in injured skin. Western analysis demonstrated marked induction of COX-2 protein beginning within 12 hours and peaking 3 days after injury. In contrast, localization of COX-1 protein and mRNA, as well as the amount of protein expression, showed no significant change during wound healing. Administration of the COX-2 inhibitor delayed re-epithelialization in the early phase of wound healing and also inhibited angiogenesis. Thus, COX-2 induction may be important in cutaneous wound healing.

Animals↗
PubMed2002

Supplementation of heterologous complement induces anti-Thy-1.1 nephritis in the Mongolian gerbil (Meriones unguiculatus).

Anti-Thy-1.1 nephritis in the rat is a popular experimental model for mesangial proliferative glomerulonephritis (GN). This model is characterized by direct binding of anti-Thy-1.1 antibody with Thy-1.1 antigen expressed on mesangial cells (MCs) of glomeruli in the rat. A single injection of anti-rat thymocyte serum (ARTS) results in GN with proteinuria and extensive mesangiolysis. Development of mesangiolysis and proteinuria are complement-dependent. We previously demonstrated Thy-1.1 antigen, similar to the rat, in thymocytes, brain cells and MCs of the kidney in the Mongolian gerbil (MG). In this study, we attempted to develop a MG nephritis model, but an injection of ARTS did not induce GN. An additional injection of guinea pig serum as a complement after ARTS injection resulted in anti-Thy-1.1 nephritis in MG. Degeneration of MCs and neutrophil infiltration were observed 1 hr after GP serum injection. Mesangiolysis and fibrin exudation occurred 12 hr after the injection and MC proliferation was apparent 7 days after the injection. In the complement-dependent hemolytic test, MG serum could not hemolyze sheep erythrocytes. These results suggested low activity, or depletion of some factors, in complements of MG serum.

Animals↗