Biomedical subjects

Masayoshi Takeuchi

Publications and source records attributed to Masayoshi Takeuchi.

50 records · Page 3Linked to original sources

PubMed2002

Effect of geranylgeranylaceton on cellular damage induced by proteasome inhibition in cultured spinal neurons.

We investigated the effect of two proteasome inhibitors, lactacystin and epoxomicin, on cultured spinal cord neurons. The incubation of spinal neurons with proteasome inhibitors for 24 hr induced neurotoxicity in a dose-dependent manner. We found motor neurons to be more vulnerable to proteasome-induced neurotoxicity than nonmotor neurons. The staining of cell bodies in treated motor neurons was markedly disrupted and showed characteristic granular patterns. Proteasome-induced neurotoxicity is accompanied by apoptotic nuclear changes, posttranslational modification of the cellular proteins, generation of intracellular free radicals, reduction in the amount of reduced glutathione, and mitochondrial dysfunction. Neurotoxicity was reduced by the administration of low concentrations (1-100 nM) of geranylgeranylacetone (GGA), which is widely used as an antiulcer drug, although higher concentrations of this drug produced neurotoxicity in spinal cord neurons. GGA was found to induce the expression of heat shock protein 70 as well as thioredoxin, which may partly contribute to the protective effect of GGA. These data suggest that the inhibition of proteasome may play a role in the mechanism of neurodegenerative diseases of the spinal cord, such as amyotrophic lateral sclerosis, and that the use of GGA may be effective in the treatment of these conditions.

Acetylcysteine↗

PubMed2002

Advanced glycation end products (AGE) and their receptor (RAGE) in the brain of patients with Creutzfeldt-Jakob disease with prion plaques.

The objective of this study was to assess the pathological role of advanced glycation end products (AGE) and the receptor for AGE (RAGE) in Creutzfeldt-Jakob disease (CJD). We immunohistochemically investigated the occipital lobe of three patients with CJD containing with prion protein (PrP) plaques using anti-AGE and RAGE antibodies. Many PrP-positive plaques were observed in these patients, and the PrP-positive prion plaques also showed immunoreactivity for the anti-AGE antibody. Furthermore, many astrocytes contained-PrP positive granules, and the same astrocytes also contained many AGE- and RAGE-immunopositive granules. The staining pattern of these granules showed good concordance with that of PrP. These findings suggest that there may be a RAGE-mediated PrP degradation pathway in CJD as is the case for beta-amyloid protein in Alzheimer's disease.

Astrocytes↗

PubMed2002

Advanced glycation end product-induced apoptosis and overexpression of vascular endothelial growth factor and monocyte chemoattractant protein-1 in human-cultured mesangial cells.

Advanced glycation end products (AGE) have been implicated in the pathogenesis of glomerulosclerosis in diabetes. However, their involvement in the development of the early phase of diabetic nephropathy has not been fully elucidated. We investigated the effects of AGE on growth and on vascular endothelial growth factor (VEGF) and monocyte chemoattractant protein-1 (MCP-1) expression in human cultured mesangial cells. We prepared three immunochemically distinct AGE by incubating bovine serum albumin (BSA) with glucose, glyceraldehyde, or glycolaldehyde. When human mesangial cells were cultured with various types of AGE-BSA, viable cell numbers as well as DNA syntheses were significantly decreased. All of the AGE-BSA were found to significantly increase p53 and Bax protein accumulations and subsequently induce apoptotic cell death in mesangial cells. An antioxidant, N-acetylcysteine, significantly prevented the AGE-induced apoptotic cell death in mesangial cells. Human mesangial cells stimulated prostacyclin production by co-cultured glomerular endothelial cells. Furthermore, various types of AGE-BSA were found to up-regulate the levels of mRNAs for VEGF and stimulate the secretion of VEGF and MCP-1 proteins in mesangial cells. The results suggest that AGE disturbed glomerular homeostasis by inducing apoptotic cell death in mesangial cells and elicited hyperfiltration and microalbuminuria by stimulating the secretion of VEGF and MCP-1 proteins, thereby being involved in the pathogenesis of the early phase of diabetic nephropathy.

Acetylcysteine↗

PubMed2002

Advanced glycation end products-induced apoptosis and overexpression of vascular endothelial growth factor in bovine retinal pericytes.

The influence of advanced glycation end products (AGEs) on apoptotic cell death and vascular endothelial growth factor (VEGF) gene expression in cultured bovine retinal pericytes was investigated. When pericytes were incubated with three immunochemically distinct AGEs, which were prepared in vitro by incubating bovine serum albumin with glucose, glyceraldehyde, or glycolaldehyde, apoptotic cell death and DNA ladder formation were significantly induced. The cytopathic effects of glyceraldehyde- or glycolaldehyde-derived AGEs were significantly enhanced in AGE receptor-transfected pericytes. Furthermore, all of these AGEs were found to upregulate the secretory forms of VEGF mRNA levels in retinal pericytes. These results suggest that AGEs disturbed retinal microvascular homeostasis by inducing pericyte apoptosis and VEGF overproduction and thus were involved in the pathogenesis of early phase diabetic retinopathy.

Acetaldehyde↗

PubMed2002

Advanced glycation endproduct-induced calcium handling impairment in mouse cardiac myocytes.

Long-standing diabetes causes cardiovascular complications including direct cardiac muscle weakening known as diabetic cardiomyopathy. This is characterized by disturbances in both cardiac contraction and relaxation, which are maintained by calcium homeostasis in cardiac cells. Our recent in vitro and in vivo studies have shown that advanced glycation endproducts (AGE) account for diabetic vasculopathy through their engagement of the receptor for AGE (RAGE). Here we show that AGE and RAGE may directly affect the myocardial Ca(2+) homeostasis. We created transgenic mice that overexpressed human RAGE in the heart and analyzed the Ca(2+) transients in cultivated cardiac myocytes (CM) from the RAGE-transgenic and non-transgenic control fetuses. RAGE overexpression was found to reduce the systolic and diastolic intracellular calcium concentration ([Ca(2+)](i)). Exposure to AGE caused a significant prolongation of the decay time of [Ca(2+)](i) in CM from control mice, and this response was augmented in CM from the RAGE transgenic mice. The results suggest that the AGE and RAGE could play an active role in the development of diabetes-induced cardiac dysfunction.

Animals↗

PubMed2002

Detection of N epsilon-(carboxymethyl)lysine (CML) and non-CML advanced glycation end-products in the anterior horn of amyotrophic lateral sclerosis spinal cord.

INTRODUCTION: The involvement of glycation in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis (ALS) was recently indicated. We previously reported the existence of an Amadori product, 1-hexitol-lysine (1-HL), which is formed in the early glycation reaction, in axonal spheroids of the anterior horn of the ALS spinal cord. OBJECTIVE: The purpose of the present study was to confirm the occurrence of the later-stage glycation reaction that follows the early glycation reaction and leads to the formation of advanced glycation end products (AGEs). METHOD: We examined whether N(epsilon)-(carboxymethyl)lysine (CML) and non-CML AGE are present in ALS spinal cords. RESULTS: Immunohistochemical staining with anti-CML antibody revealed intense positivity in the cell bodies of the remaining atrophic motor neurons and in microglia. Microglia were also positive on staining with anti-non-CML antibody. Axonal spheroids were also positive on anti-non-CML-antibody staining. Vascular endothelial cells were slightly stained by both antibodies. CONCLUSIONS: The presence of non-CML AGE in the anterior horn of the ALS spinal cord indicates that the later stage of the glycation reaction is involved in the pathology of ALS. The presence of CML in the anterior horn was also confirmed, and this may reflect augmented oxidative stress.

Aged↗

PubMed2002

Palmitate-induced apoptosis of microvascular endothelial cells and pericytes.

BACKGROUND: Recent observations in the EURODIAB Complications Study demonstrated that markers of insulin resistance are strong risk factors for retinopathy incidence in patients with diabetes. However, the molecular mechanism underlying this remains to be elucidated. In this study, we investigated the influence of palmitate, a major saturated free fatty acid in plasma, on the apoptotic cell death of cultured microvascular endothelial cells (EC) and retinal pericytes. MATERIALS AND METHODS: The intracellular formation of reactive oxygen species (ROS) was detected using the fluorescent probe CM-H(2)DCFDA. DNA synthesis was determined by measuring [(3) H]-thymidine incorporation into cells. DNA fragmentations of EC were quantitatively analyzed in an enzyme-linked immunosorbent assay, and DNA laddering was evaluated on agarose gel electrophoresis. RESULTS: Palmitate increased ROS generation in microvascular EC. Furthermore, palmitate significantly inhibited DNA synthesis and induced apoptotic cell death in EC, which were completely prevented by an antioxidant, N-acetylcysteine. Palmitate up-regulated pericyte mRNA levels of a receptor for advanced glycation end products (AGE), and thereby potentiated the apoptotic effects of AGE on pericytes. CONCLUSIONS: The results suggest that palmitate could induce apoptotic cell death in microvascular EC and pericytes through the overgeneration of intracellular ROS, and thus be involved in the development of diabetic retinopathy.

Apoptosis↗

PubMed2002

[OPB-9195].

Explore the source record for details and available documents.

Animals↗

PubMed2002

Beraprost sodium, a prostaglandin I2 analogue, protects against advanced gycation end products-induced injury in cultured retinal pericytes.

BACKGROUND: Beraprost sodium, a prostaglandin I2 analogue, has been recently reported to exhibit beneficial effects on atherosclerosis in patients with diabetes. However, effects of beraprost sodium on microvascular injury in diabetes remain to be elucidated. We have previously shown that advanced glycation end products (AGE), senescent macroproteins formed at an accelerated rate in diabetes, caused pericyte apoptosis, thus being involved in the pathogenesis of the early phase of diabetic retinopathy. In this study, we examined whether beraprost sodium can protect against AGE-induced cytotoxicity in cultured retinal pericytes. MATERIALS AND METHODS: Intracellular formation of reactive oxygen species (ROS) was detected using a fluorescent probe. DNA synthesis was determined by measuring [3H]thymidine incorporation into cells. Apoptosis was determined by DNA fragmentations, which were quantitatively measured in an enzyme-linked immunosorbent assay. RESULTS: Beraprost sodium or forskolin, a stimulator of adenylate cyclase, was found to significantly inhibit AGE-induced ROS generation and the subsequent decrease in DNA synthesis in pericytes. Both treatments significantly prevented AGE-induced apoptotic cell death in pericytes. Furthermore, beraprost sodium was found to down-regulate AGE receptor mRNA levels in pericytes. CONCLUSION: The results demonstrated that cyclic AMP-elevating agents such as beraprost sodium and forskolin protected retinal pericytes from AGE-induced cytotoxicity through its anti-oxidative properties. Our present study suggests that beraprost sodium may have therapeutic potentials in treatment of patients with early diabetic retinopathy.

Animals↗

PubMed2002

CS-886, a new angiotensin II type 1 receptor antagonist, ameliorates glomerular anionic site loss and prevents progression of diabetic nephropathy in Otsuka Long-Evans Tokushima fatty rats.

BACKGROUND: Diabetic nephropathy is a leading cause of end-stage renal disease in industrialized countries. Previous studies have documented that angiotensin converting enzyme (ACE) inhibitors consistently reduce albuminuria and retard the progression of diabetic nephropathy. However, the involvement of angiotensin II in diabetic nephropathy is not fully understood. MATERIALS AND METHODS: In this study we compared the effects of CS-866, a new angiotensin II type 1 receptor antagonist, to that of an ACE inhibitor, temocapril hydrochloride, on the development and progression of diabetic nephropathy using Otsuka Long-Evans Tokushima fatty rats, a type II diabetes mellitus model animal. RESULTS: High doses of CS-866 or temocapril treatment were found to significantly improve urinary protein and beta(2)-microglobulin excretions in diabetic rats. In electron microscopic analysis, loss of glomerular anionic sites, one of the causes of glomerular hyperpermeability in diabetic nephropathy, was found to be significantly prevented by CS-866 treatment. Light microscopic examinations revealed that both treatments ameliorated glomerular sclerosis and tubulointerstitial injury in diabetic rats. Furthermore, high doses of CS-866 or temocapril treatment significantly reduced the positive stainings for transforming growth factor-beta (TGF-beta), vascular endothelial growth factor, and type IV collagen in glomeruli of diabetic rats. CONCLUSIONS: These results indicate that intrarenal angiotensin II type 1 receptor activation plays a dominant role in the development and progression of diabetic nephropathy. Our study suggests that CS-866 represents a valuable new drug for the treatment of diabetic patients with nephropathy.

Angiotensin II Type 1 Receptor Blockers↗

PubMedDate not supplied

Serum levels of non-carboxymethyllysine advanced glycation endproducts are correlated to severity of microvascular complications in patients with Type 1 diabetes.

We investigated whether serum levels of N-(carboxymethyl)lysine (CML), non-CML advanced glycation endproducts (AGEs), or pentosidine are associated with severity of diabetic microvascular complications in patients with Type 1 diabetes. Serum levels of CML, non-CML AGE, and pentosidine were measured by an enzyme-linked immunosorbent assay in 38 males and 47 females aged 31+/-8 years (mean+/-S.D.) with Type 1 diabetes for 18.7+/-7.0 years. There was a significant correlation between serum levels of CML or non-CML AGE and current HbA(1c) level (P<.01 and P<.05, respectively). The serum levels of non-CML AGE, but not CML or pentosidine, were significantly increased as normal renal status advanced to microalbuminuria, clinical nephropathy, and hemodialysis (P<.0001) and were positively correlated with urinary albumin excretion (UAE) in patients with Type 1 diabetes (P<.0001). A significant elevation of serum non-CML AGE was found in association with the severity of diabetic retinopathy (P<.0001). We found in the present study that CML levels were also increased in the stage of simple retinopathy, the early stage of clinically evident retinopathy (P<.05). Serum levels of non-CML AGE were significantly associated with the severity of diabetic nephropathy and retinopathy, suggesting a role of non-CML AGE in the progression of microvascular complications in patients with Type 1 diabetes. Since serum levels of CML were significantly increased in patients with simple retinopathy, CML may participate in the initiation of diabetic retinopathy.

Adult↗

PubMedDate not supplied

AGE down-regulation of monocyte RAGE expression and its association with diabetic complications in type 1 diabetes.

Advanced glycation end product (AGE) engagement of a cell surface receptor for AGE (RAGE) has been implicated in the development of diabetic complications. In this study, we determined the RAGE mRNA levels in monocytes from type 1 diabetic patients and analyzed their relationship with diabetic vascular complications. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that the monocyte expression of RAGE mRNA was significantly lower in patients with retinopathy than in those without retinopathy and was also significantly down-regulated in patients with nephropathy in comparison with those without nephropathy. Experiments with monocyte-enriched cultures revealed that RAGE mRNA and protein levels were down-regulated by the exposure to glyceraldehyde-derived AGE-the recently identified high-affinity RAGE ligand. Accordingly, we then assayed for the serum levels of glyceraldehyde-derived AGE as well as those of carboxymethyllysine (CML)-the known RAGE ligand and related them to the monocyte levels of RAGE mRNA. This screen revealed a negative correlation between the two parameters. The results thus suggest that the decrease in monocyte RAGE expression can be at least partly accounted for by the ligand engagement and may be a factor contributing to the development of diabetic vascular complications.

Adolescent↗

PubMedDate not supplied

Toxic advanced glycation end products (TAGE) theory in Alzheimer's disease.

Several epidemiological studies have reported moderately increased risks of Alzheimer's disease (AD) in diabetic patients compared with general population. In diabetes mellitus, the formation and accumulation of advanced glycation end products (AGEs) progress more rapidly. Recent understanding of this process has confirmed that interactions between AGEs and their receptor (RAGE) may play a role in the pathogenesis of diabetic complications and AD. The authors have recently found that glyceraldehyde-derived AGEs (AGE-2), which is predominantly the structure of toxic AGEs (TAGE), show significant toxicity on cortical neuronal cells and that the neurotoxic effect of diabetic serum is completely blocked by neutralizing antibody against the AGE-2 epitope. Moreover, in human AD brains, AGE-2 is distributed in the cytosol of neurons in the hippocampus and parahippocampal gyrus. These results suggest that TAGE is involved in the pathogenesis of AD as well as other age-related diseases. In this review, the authors discuss the molecular mechanisms of AD, especially focusing on TAGE-RAGE system.

Alzheimer Disease↗

PubMedDate not supplied

Oral adsorbent AST-120 decreases serum levels of AGEs in patients with chronic renal failure.

Advanced glycation end products (AGEs) are senescent macroprotein derivatives that are formed at an accelerated rate in patients with chronic renal failure (CRF). AGE formation and accumulation in plasma and vascular tissues contribute to accelerated atherosclerosis in this devastating disorder. AST-120 is an oral adsorbent that attenuates the progression of CRF by removing uremic toxins. Recently, AST-120 has been reported to reduce the progression of atherosclerosis as well. However, whether AST-120 decreases serum levels of AGEs and subsequently exerts atheroprotective properties remains to be elucidated. Ten nondiabetic CRF patients were enrolled in this study. All patients were kept on regular therapeutic diet and medications throughout the study. Serum AGE levels before and after AST-120 treatments were measured using enzyme-linked immunosorbent assay. Effects of patient-derived serum on atherosclerosis-related gene expression in cultured human umbilical vein endothelial cells (HUVECs) were analyzed by semiquantitative RT-PCR. Administration of AST-120 (6 g/day) for 3 months significantly decreased serum levels of AGEs in nondiabetic CRF patients, whereas AGE levels remained unchanged in age- and renal function-matched CRF patients without AST-120 treatment (n = 6). Patient serum after AST-120 treatment significantly reduced mRNA levels of receptor for AGEs, monocyte chemoattractant protein-1, and vascular adhesion molecule-1 in HUVECs compared with serum before treatment. Moreover, in vitro, AST-120 was found to adsorb carboxymethyllysine (CML), one of the well-characterized, digested food-derived AGEs. This study suggests that atheroprotective properties of AST-120 can be ascribed, at least in part, to its AGE-lowering ability via absorption of CML.

Administration, Oral↗