Publications by authors named "Masumi Kamiyama"

Antioxidant activities of brewed coffees prepared from six commercial brands ranged from 63.13 ± 1.01 to 96.

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In the intrarenal renin-angiotensin system, angiotensinogen levels are well known to be increased in diabetes, and these enhanced intrarenal angiotensinogen levels may initiate the development and accelerate the progression of diabetic nephropathy. However, the specific localization of the augmented angiotensinogen in proximal tubule segments in diabetes is still unknown. We investigated the detailed localization of angiotensinogen in 3 proximal tubule segments in the diabetic Otsuka Long-Evans Tokushima fatty (OLETF) rats and the control Long-Evans Tokushima Otsuka (LETO) rats.

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Although recent studies have proven that renin-angiotensin system (RAS) blockades retard the progression of diabetic nephropathy, the detailed mechanisms of their reno-protective effects on the development of diabetic nephropathy remain uncertain. In rodent models, it has been reported that reactive oxygen species (ROS) are important for intrarenal angiotensinogen (AGT) augmentation in the progression of diabetic nephropathy. However, no direct evidence is available to demonstrate that AGT expression is enhanced in the kidneys of patients with diabetes.

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Diabetes mellitus is one of the most prevalent diseases and is associated with increased incidence of structural and functional derangements in the kidneys, eventually leading to end-stage renal disease in a significant fraction of afflicted individuals. The renoprotective effects of renin-angiotensin system (RAS) blockade have been established; however, the mechanistic pathways have not been fully elucidated. In this review article, the cardinal role of an activated RAS in the pathogenesis of diabetic nephropathy (DN) is discussed with a focus on 4 themes: (1) introduction to RAS cascade, (2) intrarenal RAS in diabetes, (3) clinical outcomes of RAS blockade in DN, and (4) potential of urinary angiotensinogen as an early biomarker of intrarenal RAS status in DN.

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Objectives: Angiotensinogen in the kidneys is formed primarily in the proximal tubule cells and is secreted into the tubular fluid. Structurally, proximal tubules can be divided into three segments. The first segment, segment 1 (S1) is mainly confined to the pars convoluta, the second segment, segment 2 (S2) comprises the end of pars convoluta, and the third segment, segment 3 (S3) includes the major part of the pars recta.

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Article Synopsis
  • Methanol extract from Syzygium zeylanicum leaves showed strong antioxidant properties.
  • The water extract derived from this methanol extract had the highest antioxidant activity after being processed through various solvents.
  • The active compound, identified as zeylaniin A, is a new macrocyclic ellagitannin with potent antioxidant effects confirmed through several assays.
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Urinary excretion of albumin (UAlb) is used clinically as a marker of diabetic nephropathy (DN). Although DN was thought to be a unidirectional process, recent studies demonstrated that a large proportion of patients diagnosed with DN reverted to normoalbuminuria. Moreover, despite the normoalbuminuria, one-third of them exhibited reduced renal function even during the microalbuminuric stage.

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Saponarin, a flavonoid found in young green barley leaves, possesses potent antioxidant activities, which are determined by its inhibition of malonaldehyde (MA) formation from various lipids oxidized by UV light or Fenton's reagent. Lipids used were squalene, ethyl linoleate, ethyl linolenate, ethyl arachidonate, octadecatetraenoic acid (ODTA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), cod liver oil, lecithin I, lecithin II, and blood plasma. The addition of saponarin inhibited the formation of MA from squalene upon UV irradiation at the level of 2 μmol/mL by almost 100%, whereas BHT inhibited its formation by 75% at the same level.

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The proximal tubule contains the highest expression of angiotensinogen mRNA and protein within the kidney and plays a vital role in the renal renin-angiotensin system. To study the regulation of angiotensinogen expression in the kidney in more detail, the proximal tubule needs to be accurately isolated from the rest of the nephron and separated into its three segments. The purpose of this study was to design a novel protocol using specific markers for the separation of proximal tubule cells into the three proximal tubule segments and to determine angiotensinogen expression in each segment.

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Obesity is a risk factor for type 2 diabetes mellitus (DM) and is associated with chronic kidney disease. Activation of the renin-angiotensin-aldosterone system (RAAS) is common in obesity. The RAAS is an important mediator of hypertension.

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The Nagano Purple grape (Vitis (V.) viniferaxV. labrusca) is a hybrid created by a cross between Kyoho (V.

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Aim: Equol is the main active product of daidzein metabolism, produced via specific microflora in the gut. This study aimed to clarify the effects of equol on oxidized low-density lipoprotein (OX-LDL)-stimulated apoptosis in human umbilical vein endothelial cells (HUVECs).

Methods: HUVECs were cultured in the presence of OX-LDL, and cell apoptosis was monitored by evaluating of DNA fragmentation and the production of cytoplasmic histone-associated DNA fragments.

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Using a large-scale genotyping analysis of gene-based single nucleotide polymorphisms (SNPs) in Japanese type 2 diabetic patients, we have identified a gene encoding neurocalcin delta (NCALD) as a candidate for a susceptibility gene to diabetic nephropathy; the landmark SNP was found in the 3' UTR of NCALD (rs1131863: exon 4 +1340 A vs. G, P = 0.00004, odds ratio = 1.

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To elucidate the functional roles of Wnt5b in adipogenesis, we characterized gene expression profiles in Wnt5b overexpressing 3T3-L1 cells using microarray analysis. Of the approximately 20,000 genes screened, we found that 85 genes were up-regulated and 211 genes were down-regulated in 3T3-L1 cells overexpressing Wnt5b. Among the genes regulated by Wnt5b, the expressions of insulin like growth factor-1 (IGF-1), vascular endothelial growth factor-C (VEGF-C), and WNT1 inducible signaling pathway protein 1 (WISP-1), which were known to be up-regulated by Wnt1/beta-catenin signaling, were decreased in the Wnt5b overexpressing cells.

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In order to identify small G protein (s) which contributes to the proliferation of vascular smooth muscle cells (VSMCs), we examined the effect of an HMG-CoA reductase inhibitor (cerivastatin), a farnesyltransferase inhibitor (FTI-277), a geranyl geranyl transferase inhibitor (GGTI-286) and a Rho kinase inhibitor (Y-27632) on the proliferation of cultured rat VSMCs stimulated with 20ng/ml platelet-derived growth factor (PDGF)-BB. Cerivastatin and GGTI-286, but not FTI-277, suppressed the PDGF-BB-induced activation of extracellular signal related kinase (ERK1/2). The inhibitory effect of cerivastatin on the PDGF-BB-induced activation of ERK1/2 was fully recovered by the addition of geranylgeranyl pyrophosphate (GGPP), but not farnesyl pyrophosphate (FPP).

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