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Biomedical subjects

M Iwano

Publications and source records attributed to M Iwano.

At least 37 records · Page 2Linked to original sources
PubMed2000

Molecular characterization and subcellular localization of protoporphyrinogen oxidase in spinach chloroplasts.

Protoporphyrinogen oxidase (Protox) is the last common enzyme in the biosynthesis of chlorophylls and heme. In plants, there are two isoenzymes of Protox, one located in plastids and other in the mitochondria. We cloned the cDNA of spinach (Spinacia oleracea) plastidal Protox and purified plastidal Protox protein from spinach chloroplasts. Sequence analysis of the cDNA indicated that the plastid Protox of spinach is composed of 562 amino acids containing the glycine-rich motif GxGxxG previously proposed to be a dinucleotide binding site of many flavin-containing proteins. The cDNA of plastidal Protox complemented a Protox mutation in Escherichia coli. N-terminal sequence analysis of the purified enzyme revealed that the plastidal Protox precursor is processed at the N-terminal site of serine-49. The predicted transit peptide (methionine-1 to cysteine-48) was sufficient for the transport of precursors into the plastid because green fluorescent protein fused with the predicted transit peptide was transported to the chloroplast. Immunocytochemical analysis using electron microscopy showed that plastidal Protox is preferentially associated with the stromal side of the thylakoid membrane, and a small portion of the enzyme is located on the stromal side of the chloroplast inner envelope membrane.

Amino Acid Sequence↗
PubMed2000

Reduced levels of chloroplast FtsH protein in tobacco mosaic virus-infected tobacco leaves accelerate the hypersensitive reaction.

In tobacco cultivars resistant to tobacco mosaic virus (TMV), infection results in the death of the infected cells accompanying the formation of necrotic lesions. To identify the genes involved in this hypersensitive reaction, we isolated the cDNA of tobacco DS9, the transcript of which decreases before the appearance of necrotic lesions. The DS9 gene encodes a chloroplastic homolog of bacterial FtsH protein, which serves to maintain quality control of some cytoplasmic and membrane proteins. A large quantity of DS9 protein was found in healthy leaves, whereas the quantity of DS9 protein in infected leaves decreased before the lesions appeared. In transgenic tobacco plants containing less and more DS9 protein than wild-type plants, the necrotic lesions induced by TMV were smaller and larger, respectively, than those on wild-type plants. These results suggest that a decrease in the level of DS9 protein in TMV-infected cells, resulting in a subsequent loss of function of the chloroplasts, accelerates the hypersensitive reaction.

Amino Acid Sequence↗
PubMed2000

Adrenomedullin gene transcription is decreased in peripheral blood mononuclear cells of patients with IgA nephropathy.

We measured mRNA levels of adrenomedullin (AM), C-type natriuretic peptide (CNP), vascular endothelial growth factor (VEGF), interleukin 1beta (IL-1beta) and interleukin 6 (IL-6) in peripheral blood mononuclear cells (PBMC) of patients with IgA nephropathy. To evaluate these mRNA levels, we employed a real-time quantitative PCR method which was performed using a hybridization probe labeled with two fluorescence dyes. This strategy was found to afford the standard curves with a high correlation, suggesting that this method is useful for evaluations of mRNA levels. By this method, levels of AM, CNP, VEGF, IL-1beta and IL-6 mRNA in PBMC of 49 IgA nephropathy patients and 35 healthy volunteers were evaluated. Among the mRNAs examined, AM mRNA levels were significantly lower in severe-grade than in mild-grade IgA nephropathy patients. Furthermore, AM mRNA levels correlated with CNP mRNA levels in PBMC of patients with IgA nephropathy, and each peptide generated from these mRNAs has antiproliferative effects on mesangial cells. These data indicate that gene expression of AM in PBMC is regulated according to the pathophysiological states of IgA nephropathy and that decreased AM production may contribute to the progression of IgA nephropathy.

Adrenomedullin↗
PubMed1999

The small GTP-binding protein rac is a regulator of cell death in plants.

Cell death plays important roles in the development and defense of plants as in other multicellular organisms. Rapid production of reactive oxygen species often is associated with plant defense against pathogens, but their molecular mechanisms are not known. We introduced the constitutively active and the dominant negative forms of the small GTP-binding protein OsRac1, a rice homolog of human Rac, into the wild type and a lesion mimic mutant of rice and analyzed H(2)O(2) production and cell death in transformed cell cultures and plants. The results indicate that Rac is a regulator of reactive oxygen species production as well as cell death in rice.

Amino Acid Sequence↗
PubMed1999

Relationship between polyploidy and pollen self-incompatibility phenotype in Petunia hybrida Vilm.

Self-incompatibility in Solanaceae is controlled by a single multiallelic locus, the S-locus. The S-allele associated ribonucleases (S-RNases) in the pistil are involved in pollen rejection. In this work, we analyzed two newly isolated lines of Petunia hybrida, termed PB and PF. They both had the same set of S-RNases (SB1- and SB2-RNases), however the PB was a self-incompatible diploid while PF was a self-compatible tetraploid. Cross pollination tests between PB and PF indicated diploid pollen from PF lost the incompatibility phenotype. In order to clarify the effects of polyploidy on pollen phenotypic change, we artificially induced tetraploid plants from a diploid SB1SB2 heterozygote (= PB) and a diploid SB1SB1 homozygote. The obtained SB1 SB1SB1SB1 homoallelic tetraploid remained self-incompatible, whereas the SB1SB1SB2SB2 heteroallelic tetraploid became self-compatible. These data suggested that the diploid heteroallelic pollen lost the incompatibility phenotype and had the characteristics of self-compatibility with SB1SB2 style.

Alleles↗
PubMed1999

Association of an insertion polymorphism of angiotensin-converting enzyme gene with the activity of lupus nephritis.

BACKGROUND: Lupus nephritis is a common manifestation of systemic lupus erythematosus (SLE). The pathogenesis of lupus nephritis has not been fully understood; however, immunological abnormalities have been considered in the development and activity of lupus nephritis. As angiotensin-converting enzyme (ACE) is implicated in various immunological phenomena, we investigated the correlation between insertion (I)/ deletion (D) polymorphism of the ACE gene and the activity of lupus nephritis. PATIENTS AND METHODS: Eighty-four patients with SLE and 100 healthy subjects were enrolled in this study. Following the extraction of genomic DNA from the peripheral blood, the ACE genotype was determined by the polymerase chain reaction. The patients were classified by the histological findings according to the WHO classification. In addition, the activity index and chronicity index were used to assess the severity of renal involvement. RESULTS: Individuals with II genotype showed a significantly increased activity of lupus nephritis. The allelic frequency was I/D = 0.84/0.16 in patients with WHO class IV renal lesions, and I/D = 0.36/0.64 in those with WHO class I lesions and 0.61/0.39 in patients with WHO class I or WHO class II. The difference in the allelic frequency between patients with WHO class IV and those with WHO class I or WHO class I + WHO class II was statistically significant (p = 0.00016 or p = 0.027, respectively). Moreover, lupus nephritis patients with II genotype showed significantly higher activity index than those with DD genotype (p = 0.0009). CONCLUSION: These results suggest that the insertion polymorphism of the ACE gene may correlate with the activity of lupus nephritis.

Adult↗
PubMed1998

Serum levels of VEGF and basic FGF in the subacute phase of myocardial infarction.

We examined serial changes in serum levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) measured by ELISAs in 45 patients with acute myocardial infarction (AMI) who received heparin intravenously for 3 to 5 days after the onset and in 30 control subjects with an old myocardial infarction. To evaluate the effect of heparin on these serum levels, heparin was administered intravenously in 10 patients with AMI on day 21. Blood samples were obtained from all AMI patients on days 1, 2, 3, 7, 14, 21, and 28 and from 10 AMI patients before and 1 h after heparin administration. Serum VEGF level was significantly reduced after heparin administration (P<0.001). Serum samples from day 1 to 3 were therefore excluded from the subsequent analysis. Serum VEGF level in AMI patients was significantly higher on day 7 than in the control subjects (P<0.0001), and then decreased over time (P<0.0001). The serum VEGF level on day 7 was independently associated with the peak serum CK level (P<0.05). The serum bFGF level did not differ significantly between the AMI patients and the control subjects. In conclusion, the serum VEGF level may be selectively elevated during the healing process after AMI.

Anticoagulants↗
PubMed1998

Molecular characterization of photomixotrophic tobacco cells resistant to protoporphyrinogen oxidase-inhibiting herbicides

Peroxidizing herbicides inhibit protoporphyrinogen oxidase (Protox), the last enzyme of the common branch of the chlorophyll- and heme-synthesis pathways. There are two isoenzymes of Protox, one of which is located in the plastid and the other in the mitochondria. Sequence analysis of the cloned Protox cDNAs showed that the deduced amino acid sequences of plastidial and mitochondrial Protox in wild-type cells and in herbicide-resistant YZI-1S cells are the same. The level of plastidial Protox mRNA was the same in both wild-type and YZI-1S cells, whereas the level of mitochondrial Protox mRNA YZI-1S cells was up to 10 times the level of wild-type cells. Wild-type cells were observed by fluorescence microscopy to emit strong autofluorescence from chlorophyll. Only a weak fluorescence signal was observed from chlorophyll in YZI-1S cells grown in the Protox inhibitor N-(4-chloro-2-fluoro-5-propagyloxy)-phenyl-3,4,5, 6-tetrahydrophthalimide. Staining with DiOC6 showed no visible difference in the number or strength of fluorescence between wild-type and YZI-1S mitochondria. Electron micrography of YZI-1S cells showed that, in contrast to wild-type cells, the chloroplasts of YZI-1S cells grown in the presence of N-(4-chloro-2-fluoro-5-propagyloxy)-phenyl-3,4,5, 6-tetrahydrophthalimide exhibited no grana stacking. These results suggest that the herbicide resistance of YZI-1S cells is due to the overproduction of mitochondrial Protox.

Journal Article↗
PubMed1998

Increased excretion of urinary transforming growth factor beta 1 in patients with diabetic nephropathy.

The accumulation of extracellular matrix in the glomeruli of human and experimental models of diabetic nephropathy is associated with disease progression. Transforming growth factor beta 1 (TGF-beta1), which is a multifunctional peptide growth factor, plays a key role in the synthesis of extracellular matrix protein in vitro, and the expression of TGF-beta1 is elevated in human and rat diabetic nephropathy. In this study, we measured the urinary TGF-beta1 excretion in 57 patients with non-insulin-dependent diabetes mellitus and in 20 healthy volunteers to examine whether the determination of urinary TGF-beta1 excretion would facilitate the evaluation of the degree of mesangial expansion in patients with diabetic nephropathy. Both active and total TGF-beta1 levels in 24-hour urine samples collected from patients with diabetes mellitus and normal controls were measured using an enzyme-linked immunosorbent assay. We observed a higher excretion of urinary TGF-beta1 in patients with diabetes mellitus than in normal controls. In addition, the urinary TGF-beta1 excretion was elevated in patients with severe mesangial expansion. These results suggest that urinary TGF-beta1 may represent one parameter that can be used to evaluate the progression of diabetic nephropathy.

Biomarkers↗
PubMed1998

Measurement of plasma and urinary adrenomedullin in patients with IgA nephropathy.

In this study, we measured plasma and urinary adrenomedullin (AM) concentrations in 47 patients with IgA nephropathy. Controls were 39 healthy volunteers. Plasma and urinary AM values were measured by specific radioimmunoassay. The plasma AM concentrations were higher, and the urinary AM levels were lower in patients with IgA nephropathy than in healthy volunteers. Plasma AM concentrations showed a positive correlation with serum creatinine and blood urea nitrogen, whereas urinary AM levels correlated negatively with serum creatinine and blood urea nitrogen. The plasma AM concentrations showed a positive correlation with fractional excretions of sodium and potassium. Renal biopsy specimens of patients without renal failure were scored for activity (percentage of glomeruli demonstrating cellular crescent formation, degree of mesangial proliferation and interstitial infiltration; total score = 9). Urinary AM levels were shown to be lower in the group with a high activity (score 3-9) as compared with the group with a low activity (score 0-2) based on renal biopsy. Thus, urinary levels of AM are affected by the degree of the activity in IgA nephropathy, and AM may participate in the pathophysiology of IgA nephropathy.

Adrenomedullin↗
PubMed1998

Plasma and urinary levels of adrenomedullin in chronic glomerulonephritis patients with proteinuria.

In this study, we measured levels of plasma and urinary adrenomedullin (AM) in 37 patients with chronic glomerulonephritis including minimal change nephrotic syndrome, focal segmental glomerulosclerosis or membranous nephropathy that can induce severe proteinuria. Thirty-nine healthy volunteers were enrolled as controls. Plasma and urinary AM levels were measured by an AM-specific radioimmunoassay. Plasma AM concentrations were higher and urinary AM levels were lower in patients with chronic glomerulonephritis than in healthy volunteers. Patients were divided into two groups according to urinary excretion of protein for 24 h (UPro, g/day) which reflects the disease activity or glomerular damage of the glomerulonephritis (group I: Upro < 1, group II: Upro >= 1). Plasma AM levels positively and urinary AM-levels negatively correlated with the degree of proteinuria. These results suggest that plasma and urinary AM levels in patients with chronic glomerulonephritis reflect the disease activity or glomerular damage represented by the degree of proteinuria.

Adrenomedullin↗
PubMed1998

Association of an insertion polymorphism of angiotensin-converting enzyme gene with the activity of systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) shows various clinical manifestations, which are characterized by inflammation in many different organ systems. The cause of SLE is still unclear; however, the immunological abnormalities are considered to be responsible for the pathogenesis of SLE. As angiotensin I-converting enzyme (ACE) has been reported to be associated with various immunological phenomena, we investigated the correlation between insertion (I)/deletion (D) polymorphism of the ACE gene and the disease activity of SLE. Ninety-three patients with newly diagnosed SLE were enrolled in this study. ACE genotype was determined by the polymerase chain reaction (PCR). We measured serum levels of anti-double-stranded (ds) DNA antibody (Ab) and serum levels of total complements (CH50) as the parameter for lupus activity. Moreover, we evaluated the clinical disease activity by calculating SLE disease activity index (SLEDAI). Individuals with II genotype showed a significant increase in SLE activity. Patients with the ACE II genotype showed a higher serum level of anti-dsDNA Ab (14.3 IU/ml (5.475, 74.6, median (25th centile, 75th centile)) than those with the DD genotype (4.65IU/ml (4.05, 6.8)) (P<0.01). Moreover, patients with the 11 genotype also showed lower levels of serum CH50 than those with the DD genotype (P < 0.01). Patients with the II1 or DI genotype had significantly higher SLEDAI score than those with the DD genotype (P < 0.01). These results suggest that the ACE genotype could be associated with the disease activity of SLE. ACE insertion polymorphism might be used as one of predictive factors for the activity of lupus.

Adult↗
PubMed1998

[The usefulness of MRCP in the initial diagnosis of the biliary and pancreatic diseases compared with ERCP].

The purpose of this study was to determine the effectiveness and the limitation of the MR cholangiopancreatography (MRCP) in the initial diagnosis for the biliary and pancreatic diseases compared with the image of Endoscopic retrograde cholangiopancreatography (ERCP). MRCP showed higher performance toward the discovery of the choledocholithiasis of a diameter 4 mm and more. Furthermore, MRCP reflected a malignant tumor at the constrictive part and the dilated proximal part of the biliary and pancreatic duct in 23 example all. An advantage of ERCP was the ability to carry out biopsies and therapeutic procedures, such as biliary drainage and sphincterotomy, while MRCP was an important diagnostic modality in the work-up of the biliary and pancreatic diseases and could help in planning treatment. MRCP would become the examination method first used, and it would be popularized all the more from now on.

Bile Duct Neoplasms↗
PubMed1997

Globular and fibrous structure in barley chromosomes revealed by high-resolution scanning electron microscopy.

Barley chromosomes were prepared for high-resolution scanning electron microscopy using a combination of enzyme maceration, treatment in acetic acid and osmium impregnation using thiocarbohydrazide. Using this technique, the three-dimensional ultrastructure of interphase nuclei and mitotic chromosomes was examined. In Interphase, different levels of chromatin condensation were observed, consisting of fibrils 10 nm in diameter, 20- to 40-nm fibres and a higher order complex. In prophase, globular and strand-like structures composed of 20- to 40-nm fibres were dominant. As the cells progressed through the cell cycle and the chromatin condensed, globular and strand-like structures (chromomeres) were coiled and packed to form chromosomes. Chromomeres were observed as globular protuberances on the surface of metaphase chromosomes. These findings indicate that the chromomere is a fundamental substructure of the higher order architecture of the chromosome. In the centromeric region, there were no globular protuberances, but 20- to 40-nm fibres were folded compactly to form a higher level organization surrounding the chromosomal axia.

Chromatin↗
PubMed1997

Reversible glomerular hypertrophy in adult patients with primary focal segmental glomerulosclerosis.

The present study was performed to assess the pathogenetic role of glomerular hypertrophy in patients with primary focal segmental glomerulosclerosis (FSGS). We studied 14 patients with FSGS by morphometry. In seven patients, minimal change nephrotic syndrome (MCNS) was diagnosed on the first renal biopsy, but FSGS was diagnosed on the second biopsy (MCNS-FSGS group). Seven other patients with FSGS on the first biopsy underwent second biopsies while in remission (FSGS-R group). Biopsy results were compared with biopsies from 10 patients with MCNS and seven control subjects. Nonsclerotic glomeruli were examined. The mean glomerular tuft area, whole glomerular area, and number of mesangial cells were significantly increased in both biopsies from the MCNS-FSGS group and in the first biopsies obtained during the nephrotic stage of the FSGS-R group, compared with control subjects and patients with MCNS. Biopsies from FSGS patients in remission showed that the mean glomerular tuft area and number of mesangial cells were significantly decreased. The fractional extracellular matrix area (extracellular matrix area/glomerular tuft area) and mesangial cell density (mesangial cell number/glomerular tuft area) in FSGS during both nephrotic and remission stages were the same as those in control subjects and patients with MCNS. The present study suggests that glomerular hypertrophy precedes the development of glomerulosclerosis in FSGS and is reversible when patients are in remission. These features support the pathogenetic importance of glomerular hypertrophy in patients with primary FSGS.

Adult↗
PubMed1997

[The influence of anti-interferon-alpha 2a antibodies in initial daily four-week interferon-alpha 2a therapy for chronic hepatitis C].

Thirty-two patients with chronic active hepatitis C were initially treated with 9 million units of interferon (IFN)-alpha 2a daily for 4 weeks and then thrice weekly for 20 weeks. The incidence of development and influence on clinical effectiveness of anti-IFN alpha 2a neutralizing antibodies measured by bioassay were investigated. Thirteen (41%) of the 32 patients developed antibodies, 4 (12.5%) of whom exhibited a high titer of 128 NU or greater. There was a significant difference (p < 0.05) between responders and non-responders in the low viral load group (less than 10(5) copies/50 microliters) in the incidence of antibody development, with antibodies present in 2 of the 9 responders (22%) and 5 of the 7 non-responders (71%). There was also a significant difference between the antibody-negative and antibody-positive patients in circulating HCV-RNA, 2-5AS activity and average ALT levels at the latter half of treatment. In addition, 2-5AS activity was significantly lower (p < 0.05) at completion of treatment in the high antibody titer group (128 NU or greater) than in the low antibody titer group. These results indicate that the development of anti-IFN neutralizing antibodies had a definite influence on the clinical course of IFN treatment for chronic hepatitis C.

Adult↗