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Biomedical subjects

Michio Nagata

Publications and source records attributed to Michio Nagata.

At least 19 recordsLinked to original sources
PubMed2006

Stable transgene expression in mice generated from retrovirally transduced embryonic stem cells.

Silencing of transduced genes hampers production of transgenic mice using retroviral vectors. We show stable expression of the enhanced green fluorescent protein (EGFP) gene in chimeric mice generated from retrovirally transduced embryonic stem cells. The vector was a murine stem cell virus-typed retroviral vector (GCDsap) in which the long terminal repeat and primer-binding site were derived from a PCC4 cell-passaged myeloproliferative sarcoma virus and the endogenous retrovirus dl587rev, respectively. To increase the viral titer, the vector was packaged with vesicular stomatitis virus G protein, which allowed concentration of the virus into pellets followed by resuspension in serum-free medium. In chimeric mice, EGFP was detected in various tissues including hematopoietic cells, neurons, cardiac muscle, and intestine. Furthermore, high expression was maintained in the progeny of these mice, suggesting successful germline transmission of active proviruses. Although the proportion of EGFP-expressing cells and the mean intensity of EGFP expression varied among tissues and mice, 100% of peripheral blood leukocytes expressed EGFP in mice carrying a single provirus copy, as well as in their progeny. Therefore, the gene transfer system described here provides a useful tool not only to generate transgenic animals but also to manipulate human embryonic stem cells..

Animals↗
PubMed2006

Triggers of relapse in steroid-dependent and frequently relapsing nephrotic syndrome.

An awareness of the triggers of relapse is critical for the control of steroid-dependent, frequently relapsing nephrotic syndrome (SDFRNS). We have investigated the triggers, usually described as 'episodes', to such relapses within a temporal context. Thirty-five patients with SDFRNS were analyzed retrospectively. A total of 442 relapses occurred in 2499 patient-months. The relapses were classified into two groups: those with episodes (E+) and those without episodes (E-). There were 135 E+ relapses and 296 E- relapses. The common cold was the most common episode (52%) of E+ relapse, followed by school events (18%). These E+ relapses occurred almost evenly throughout the 4 weeks between each follow-up visit. Conversely, 161 (55%) of the 296 E-z relapses occurred within the 3-day period preceding the patient's appointment (relapse-related hospital visit, RRHV). McNemar's test revealed that the concentration of relapses in this period was statistically significant (P < 0.00011). In addition, 15 out of 26 RRHV without additional therapy showed a spontaneous remission. From a chronological perspective, the common cold and school events as well as up-coming hospital visits may trigger relapses in SDFRNS patients.

Adolescent↗
PubMed2006

Role of integrin-linked kinase in epithelial-mesenchymal transition in crescent formation of experimental glomerulonephritis.

BACKGROUND: Glomerular parietal epithelial-mesenchymal transition (EMT) is a key event in crescent formation of glomerulonephritis (GN). Integrin-linked kinase (ILK) is an integrin cytoplasmic-binding protein that has been implicated in the regulation of cell adhesion, extracellular matrix organization and EMT. Transforming growth factor-beta (TGF-beta) is involved in the induction and progression of EMT in several tissues. METHODS: To investigate whether ILK is involved in the crescent formation in GN, we studied the expression of ILK protein and activity in crescentic GN induced in Wistar Kyoto (WKY) rats. In addition, we investigated whether transforming growth factor-beta1 (TGF-beta1) could induce glomerular EMT and ILK by using cultured parietal epithelial cell (PEC). RESULTS: The expression of ILK was strongly induced in cellular crescents at day 7 and followed by a decrease in fibrocellular crescents at day 28. ILK-expressing cells in cellular crescents were double-positive for protein gene product 9.5 (PEC marker), alpha-smooth muscle actin (alpha-SMA, myofibroblasts marker) and TGF-beta1, indicating a possible contribution of ILK and TGF-beta1 to EMT in crescent formation in GN. Consistent with the finding of histological ILK expression in crescents, western blot and kinase activity assay showed an increase in both ILK protein and activity, peaking at day 7 of GN (3.7- and 3.5-fold of control, respectively). The expression of ILK increased to 3.1-fold of control when EMT was induced in cultured PEC by TGF-beta1. CONCLUSION: The present results provide the first evidence that expression and activity of ILK are increased in cellular crescents of experimental GN. Enhanced expression and activity of ILK, possibly by TGF-beta1, is associated with the induction of EMT by PEC and thereby, may participate in the formation of cellular crescents in GN.

Animals↗
PubMed2006

Characterization of diabetic nephropathy in a transgenic model of hypoinsulinemic diabetes.

Genetic mouse models provide a unique opportunity to investigate gene function in the natural course of the disease. Although diabetic nephropathy (DN) in models of type II diabetes has been well characterized, diabetic renal disease in hypoinsulinemic diabetic mice is still incompletely understood. Here, we characterized renal changes in the pdx1(PB)-HNF6 transgenic mouse that exhibits beta-cell dysfunction and nonobese hypoinsulinemic diabetes. Male transgenic mice developed hyperglycemia by the age of 7 wk and survived for over 1 yr without insulin treatment. Diabetes ensued earlier and progressed more severely in the HNF6 males than the females. The HNF6 males exhibited albuminuria as early as 10 wk of age, and the urinary albumin excretion increased with age, exceeding 150 microg/24 h at 11 mo of age. Diabetic males developed renal hypertrophy after 7 wk of age, whereas glomerular hyperfiltration was not observed in the mice. Hypertension and hyperlipidemia were not observed in the diabetic mice. Histological analysis of the HNF6 kidneys displayed diabetic glomerular changes, including glomerular enlargement, diffuse mesangial proliferation and matrix expansion, thickened glomerular basement membrane, and arteriolar hyalinosis. Mesangial matrix accumulation increased with age, resulting in nodular lesions by 44 wk of age. Immunohistochemistry showed accumulation of type IV collagen and TGF-beta1 in the mesangial area. No significant immune complex deposition was observed in the HNF6 glomeruli. Thus the HNF6 mouse exhibits diabetic renal changes that parallel the early phase of human DN. The model should facilitate studies of genetic and environmental factors that may affect DN in hypoinsulinemic diabetes.

Albuminuria↗
PubMed2006

Tissue-specific distribution of an alternatively spliced COL4A5 isoform and non-random X chromosome inactivation reflect phenotypic variation in heterozygous X-linked Alport syndrome.

A novel type of hereditary transmission of COL4A5 in a Japanese family with X-linked Alport syndrome was detected through analysis of cDNA sequences and an X-chromosome inactivation assay. A female patient with moderately altered renal function, who was diagnosed with Alport syndrome by renal biopsy, and her mother, who was undergoing maintenance haemodialysis, showed similar tissue-specific expression of a truncated isoform of COL4A5, which was generated by alternative splicing without a splice-site mutation. Expression of the truncated isoform occurred in the renal specimen derived from the patient, but not in specimens from controls. Genomic analysis revealed two point mutations (c.4821 + 121, T>C; c.4822-151_150, ins T) in intron 49 of COL4A5 from the patient. The peripheral blood mononuclear cells of the patient and her mother showed non-random lyonization. While the females showed only renal impairment, an affected male in the same family suffered from severe renal insufficiency, visual defect and hearing disturbances. Hence, we suggest that this type of heredity COL4A5 presents with phenotypic variation in female heterozygous X-linked Alport syndrome patients.

Adult↗
PubMed2006

Renal failure due to tubulointerstitial nephropathy in an infant with cranioectodermal dysplasia.

Cranioectodermal dysplasia (CED) is a rare autosomal recessive disease with characteristic craniofacial, skeletal, and ectodermal-derived tissue abnormalities. In this disease, tubulointerstitial nephropathy (TIN) has been reported as one of the life-threatening combinations. Here we report a sporadic case of CED showing signs of renal failure during the perinatal period. Renal biopsy at the age of 6 months revealed TIN consisting of marked interstitial fibrosis with inflammatory cell infiltration accompanied by scattered tubular atrophy. Glomeruli were often sclerosed and others showed prominent immaturity; the findings are supportive of progressive deterioration of renal function in this infant. This case suggests that TIN in CED can occur during the fetal period and progress rapidly, leading to end-stage renal failure in infancy.

Abnormalities, Multiple↗
PubMed2006

Focal segmental glomerulosclerosis associated with essential thrombocythemia.

Focal segmental glomerulosclerosis (FSGS) is a primary glomerular disease that is characterized by progressive proteinuria and declining renal function. Secondary FSGS is known to be associated with various diseases. However, an association of FSGS with essential thrombocythemia (ET) has been reported in few cases. We report a 76-year-old man who presented with nephrotic syndrome and hepatosplenomegaly. He had thrombocythemia after a splenectomy, which had been carried out at a nearby hospital. A renal biopsy showed that he had focal segmental glomerulosclerosis (FSGS), while assessment of the bone-marrow specimen revealed that he had ET. A possible relationship between FSGS, which occurred in association with a dramatic increase of thrombocytes after a splenectomy in a patient with ET, and increased serum levels of transforming growth factor (TGF)-beta, basic fibroblast growth factor (bFGF), and platelet-derived growth factor (PDGF)-BB was suggested.

Aged↗
PubMed2006

Early recurrence of dense deposit disease with marked endocapillary proliferation after renal transplantation.

Dense deposit disease (DDD), also known as type II membranoproliferative glomerulonephritis (MPGN), is characterized by the presence of continuous intramembranous dense deposits. At present, the histogenesis of DDD is not well known. Reported herein are two cases of early recurrence of DDD in renal allografts, with marked endocapillary proliferation. In case 1 the first allograft biopsy revealed electron-dense deposits mainly in the subendothelial and mesangial areas along with subepithelial humps, but a continuous intramembranous deposition was not obvious. In the sequential biopsy, the deposits were more often seen in the intramembranous area and finally formed a continuous osmiophilic substance, which is a characteristic feature of DDD. In case 2, continuous intramembranous deposition already coexisted with endocapillary proliferation at the first biopsy. In both cases, endocapillary proliferation was alleviated slightly as time progressed. The present report suggests that endocapillary proliferative glomerulonephritis is the earliest lesion in some cases of DDD. Detailed review of a clinical history and a subsequent follow-up biopsy should be done to distinguish these lesions from other types of endocapillary proliferative glomerulonephritis.

Adolescent↗
PubMed2006

MafB is essential for renal development and F4/80 expression in macrophages.

MafB is a member of the large Maf family of transcription factors that share similar basic region/leucine zipper DNA binding motifs and N-terminal activation domains. Although it is well known that MafB is specifically expressed in glomerular epithelial cells (podocytes) and macrophages, characterization of the null mutant phenotype in these tissues has not been previously reported. To investigate suspected MafB functions in the kidney and in macrophages, we generated mafB/green fluorescent protein (GFP) knock-in null mutant mice. MafB homozygous mutants displayed renal dysgenesis with abnormal podocyte differentiation as well as tubular apoptosis. Interestingly, these kidney phenotypes were associated with diminished expression of several kidney disease-related genes. In hematopoietic cells, GFP fluorescence was observed in both Mac-1- and F4/80-expressing macrophages in the fetal liver. Interestingly, F4/80 expression in macrophages was suppressed in the homozygous mutant, although development of the Mac-1-positive macrophage population was unaffected. In primary cultures of fetal liver hematopoietic cells, MafB deficiency was found to dramatically suppress F4/80 expression in nonadherent macrophages, whereas the Mac-1-positive macrophage population developed normally. These results demonstrate that MafB is essential for podocyte differentiation, renal tubule survival, and F4/80 maturation in a distinct subpopulation of nonadherent mature macrophages.

Animals↗
PubMed2006

Charge selective function in childhood glomerular diseases.

The charge selectivity (CS) function in human renal disease has not been unequivocally demonstrated to date. However, the clearance ratio of IgA to IgG may be theoretically useful in estimating CS in humans, since IgA and IgG have similar sizes and tertiary structures, but distinct isoelectric points (3.5-5.5 [IgA] and 4.5-9.0 [IgG]), and Stokes-Einstein radius: 61 A (IgA) and 49-60 A (IgG). Two-dimensional electrophoresis with the following immunoblotting revealed that the considerably anionic portion (isoelectric points [pI] <4.0) of IgA, visible in serum, was absent in the urine in steroid-sensitive nephrotic syndrome (SSNS) but present in the same during IgA nephropathy (IgAN) and membranoproliferative glomerulonephritis (MPGN). A latex assay revealed the CS index (CSI) was significantly low in patients with podocyte disease (group A), including SSNS, focal and segmental glomerulosclerosis (FSGS) and Finnish-type congenital nephrotic syndrome (FCNS), but high in those with Alport syndrome (AS), IgAN, Henoch-Schönlein purpura nephritis (HSPN), and MPGN (group B). The linear regression analysis of the IgA size selectivity index (IgA SSI; clearance ratio of IgA to transferrin) and SSI (clearance ratio of IgG to transferrin), which represents the clearance ratio of IgA to IgG referring to the transferrin clearance, revealed the influence of the charge more accurately. Indeed, the slope of the regression lines of IgA SSI (y) to SSI (x) were concluded to be y = 0.39x (group A) and y = 1.05x (group B), respectively. These results suggested that the charge selective barrier among podocyte diseases (group A) is preserved to some degree, but lost in cases of nephritis and AS (group B).

Adolescent↗
PubMed2005

Murine metanephric mesenchyme possesses characteristics of vascular endothelial cells in vitro.

BACKGROUND/AIMS: Although the renal microvasculature, including the glomerular capillaries, is generally considered to develop from the metanephric mesenchyme, this has not been unequivocally demonstrated. Using a murine metanephric mesenchymal cell line (MS7), we tested whether the metanephric mesenchyme expresses phenotypic characteristics of endothelial cells and differentiates into vascular endothelial cells in vitro. METHODS: MS7 cells were examined for the mRNA expression of endothelial markers by reverse transcription (RT)-PCR. Moreover, we attempted to induce the appearance of new endothelial markers by stimulation with growth factors and exposure to hypoxia. RESULTS: Before induction, MS7 cells expressed mRNA of fetal liver kinase 1 (Flk1), fms-like tyrosine kinase (Flt1), tyrosine kinase with Ig and EGF homology domains 2 (Tie2), CD31, and podocalyxin. However, they did not express mRNA for vascular endothelial-cadherin (VE-cadherin) or von Willebrand factor (vWF), which are markers specific for endothelial cells and mature endothelial cells. In the immunocytochemical analysis, MS7 absorbed DiI-acetylated LDL virtually, but the results of staining with anti-VE-cadherin, vWF, or CD31 antibodies were negative. MS7 cells that were cultured for 14 days after reaching confluence began to express VE-cadherin and vWF mRNA. In addition, immunofluorescence showed abundant granules stained with anti-vWF antibody in the cytoplasm. Stimulation with vascular endothelial growth factor (VEGF), or basic fibroblast growth factor (bFGF), or exposure to a hypoxic condition did not influence their characteristic changes. CONCLUSION: Our results suggest that metanephric mesenchymal (MS7) cells possess some characteristics of endothelial cells, and they are potent to differentiate into mature vascular endothelium in vitro.

Animals↗
PubMed2005

Unilateral renal angiodysplasia in a girl with hypertension.

We report a case of very unusual renal vascular anomaly: angiodysplasia. The patient suffered from acute pyelonephritis immediately after birth. Renal ultrasonography, performed at age 1 day, revealed an enlarged left kidney with heterogeneously increased echogenicity, which involuted rapidly in 3 months. At age 10 years, she presented with severe hypertension during a course of acute pyelonephritis. Peripheral plasma renin activity was high. Computed tomographic angiogram revealed a very small but functioning left kidney. A single, narrow, left renal artery did not have focal stenosis. Pathology examination revealed dysplastic arterioles at the subcapsular area. After left nephrectomy, the blood pressure and the plasma renin activity were normalized. In conclusion, this is an unusual case of renal angiodysplasia, which induced renin-dependent hypertension.

Angiodysplasia↗
PubMed2005

Nephrotic syndrome and aberrant expression of laminin isoforms in glomerular basement membranes for an infant with Herlitz junctional epidermolysis bullosa.

Herlitz junctional epidermolysis bullosa (H-JEB) is a hereditary bullous disease caused by absent expression of laminin-5, a component of anchoring filaments within the dermal-epidermal basement membrane zone. Affected individuals usually die during the first 1 year of life. We studied an infant with H-JEB who presented with nephrotic syndrome, a previously unreported complication that may contribute to early death in this disease. DNA analysis revealed a compound heterozygote for mutations 2379delG and Q995X in the LAMB3 gene. The patient had massive albuminuria, attributable to failure of the glomerular filtration barrier, and high urinary N-acetylglucosaminidase levels, indicating renal tubular involvement. Electron-microscopic examination of the renal tissue revealed diffuse fusion of the foot processes, irregular swelling of the lamina rara interna, and disappearance of endothelial cell fenestrations. Immunohistopathologic analysis of the patient's renal tissue revealed compositional changes in laminin isoforms of the glomerular basement membrane and no detectable laminin-5 in the renal tubular basement membrane, which suggests that laminin-5 may play an important role in renal function. Our findings strongly suggest that H-JEB should be considered in the spectrum of congenital nephrotic syndromes. Combination therapy with meticulous skin care and treatment strategies established for congenital nephrotic syndromes may rescue patients with this disease.

Basement Membrane↗
PubMed2005

Primary osteogenic sarcoma of the ethmoid sinus: a case report.

Primary osteogenic sarcoma arising from the ethmoid sinus is an extremely rare condition. We report herein a 50-year-old female presenting with lacrimation. Computed tomography (CT) scan showed tumor calcification, which is a common feature of osteogenic sarcoma. Exploratory ethmoidectomy was performed, and histological examination confirmed the diagnosis of osteogenic sarcoma. Radiation therapy and chemotherapy failed to reduce the tumor size. The patient was finally treated by anterior craniofacial resection and orbital exenteration. Although primary osteogenic sarcoma of the ethmoid sinus is uncommon, the authors emphasize that osteogenic sarcoma should be suspected when tumor calcification was observed on CT scan and that adequate surgical resection with negative surgical margins remains the mainstay of treatment of this lesion.

Ethmoid Bone↗
PubMed2005

A familial case of multicystic dysplastic kidney.

A familial case of multicystic dysplastic kidney (MCDK) is described. The proband is a one-year-old boy with left MCDK, and his father was also revealed to have unilateral MCDK. The mother had two abortions; the second pregnancy was terminated because of bilateral MCDK of the fetus (Potter anomaly). The two patients and the aborted male fetus did not have any malformations except for MCDK. Thus in this family MCDK occurs as an isolated phenomenon in three individuals within two generations, presumably as a result of autosomal dominant inheritance.

Adult↗
PubMed2005

Acute interstitial nephritis predisposed a six-year-old girl to minimal change nephrotic syndrome.

A six-year-old girl was admitted to our hospital with acute renal failure. We made a clinical diagnosis of acute interstitial nephritis and oral corticosteroid therapy was started. Her renal failure soon recovered, and renal biopsy showed acute interstitial nephritis by light microscopy with glomerular foot process effacement by electron microscopy. Although her proteinuria was not heavy at the time of biopsy, her proteinuria subsequently increased to show nephrotic syndrome. We continued to give corticosteroids and her nephrotic syndrome went into remission 13 days after biopsy. Serological and bacteriological examination showed no evidence of known pathogen or drug hypersensitivity. The time changes in proteinuria were monitored by fractional total protein excretion (FETP) and fractional beta2 microglobulin excretion (FEbeta2MG) in order to evaluate the severity of proteinuria under different glomerular filtration rates and different proximal tubular functions. The results revealed that nephrotic syndrome had occurred during recovery from acute interstitial nephritis. This is the first case report to show the sequential occurrence of acute interstitial nephritis and nephrotic syndrome based on evidence from fractional protein excretion.

Acute Disease↗