Biomedical subjects

Kaori Yamada

Publications and source records attributed to Kaori Yamada.

7 recordsLinked to original sources

PubMed2007

Effect of pyridoxamine (K-163), an inhibitor of advanced glycation end products, on type 2 diabetic nephropathy in KK-A(y)/Ta mice.

Advanced glycation end products (AGEs) from the Maillard reaction contribute to the pathogenesis of diabetes-associated complications such as diabetic nephropathy. In therapeutic interventions for reducing AGEs, many compounds have been reported as AGE inhibitors. The objective of the present study was to examine the effect of pyridoxamine (K-163), an AGE inhibitor, in type 2 diabetic KK-A(y)/Ta mice. KK-A(y)/Ta mice were given pyridoxamine (200 or 400 mg/kg per day) starting at 8 weeks of age for 12 weeks. They were divided into 3 groups as follows: pyridoxamine 200 mg/kg per day treatment group (n = 10), pyridoxamine 400 mg/kg per day treatment group (n = 10), and a tap water group as the control group (n = 20). The urinary albumin/creatinine ratio (ACR), body weight (BW), levels of fasting and casual blood glucose, blood glycated hemoglobin (HbA(1c)), fasting serum insulin, triglyceride (TG), total cholesterol (T-Cho), and 3-deoxyglucosone (3DG), and systemic blood pressure were measured as biochemical parameters. N(epsilon)-(Carboxymethyl)lysine (CML) and nitrotyrosine accumulations in glomeruli were evaluated by immunohistochemical analyses. Transforming growth factor beta1 (TGF-beta1) and laminin-beta1 messenger RNA expressions in the kidneys were evaluated by real-time polymerase chain reaction. Pyridoxamine, especially at 400 mg/kg per day, improved the levels of urinary ACR, fasting serum TG, and 3DG. CML and nitrotyrosine accumulations in glomeruli were decreased. Furthermore, large doses of pyridoxamine prevented not only urinary ACR but also increases of BW, casual blood glucose, and HbA(1c). TGF-beta1 and laminin-beta1 messenger RNA expressions in kidneys were significantly lower than those in the controls. There were no significant changes in the levels of fasting blood glucose, serum T-Cho, and systemic blood pressure among all groups. It appears that pyridoxamine improved urinary ACR by its anti-AGE and anti-oxidant effects in the kidneys of KK-A(y)/Ta mice.

Animals↗

PubMed2006

Antioxidant and prooxidant activities of B group vitamins in lipid peroxidation.

The antioxidant and prooxidant activities of six B group vitamins against hydroperoxide generation in linoleic acid peroxidation were analyzed by the aluminum chrolide method. The B group vitamins were divided into three types by their antioxidant and prooxidant properties. The first type, including B1, B2 vitamin, nicotinic acid and folic acid, showed prooxidant activities in the early phase (1 week) of the linoleic acid peroxidation at concentrations of 2.5 microM-2.5 mM, but caused relatively strong antioxidant activities in the later phase reaction (3 weeks) at the same concentrations. The second type, such as B12 vitamin, did not cause significant effects in the early phases (1-2 weeks) of linoleic acid peroxidation, but exhibited significant antioxidant activities in the later phase reactions (3 weeks). The third type, such as B6 vitamin, exhibited significant antioxidant activity in the early phase reaction and caused strong antioxidant effects in the later phase reaction (3 weeks). Generally, the antioxidant activities of B group vitamins in the later phases of lipid peroxidation was much stronger than those in the earlier phases. These experimental results suggest a possibility that B group vitamins have both antioxidant and prooxidant effects on lipid peroxidation under different experimental conditions.

Antioxidants↗

PubMed2006

Paddlewheel dirhodium complexes bridged by para-substituted benzoates.

The dirhodium complex bis(benzonitrile)tetrakis[mu-4-(diethylamino)benzoato-kappa2O:O']dirhodium(II)(Rh-Rh) benzonitrile disolvate, [Rh2(C11H14NO2)4(C7H5N)2].2C7H5N, lies about an inversion centre. The dirhodium complex (methanol)tetrakis(mu-4-nitrobenzoato-kappa2O:O')(pyridine)dirhodium(II)(Rh-Rh) dichloromethane solvate, [Rh2(C7H4NO4)4(C5H5N)(CH4O)].CH2Cl2, lies in a general position in the unit cell, but the complexes dimerize around an inversion centre via O-H...O hydrogen bonding of the axial MeOH to a carboxylate O atom. In the latter crystal structure, pi-pi stacking interactions between the bridging 4-nitrobenzoate ligands and the axial pyridine ligand are observed between adjacent molecules.

Journal Article↗

PubMed2006

Glomerular changes in the KK-Ay/Ta mouse: a possible model for human type 2 diabetic nephropathy.

BACKGROUND: In type 2 diabetic nephropathy, there is no animal model which has been completely matched with humans. Advanced glycation end products (AGE) and transforming growth factor-beta (TGF-beta) are closely related to hyperglycaemia and their pathobiochemistry could explain diabetic nephropathy. The objective of the present study was to evaluate the KK-A(y)/Ta mouse as a suitable model for type 2 diabetic nephropathy including pathological changes and immunohistochemical analyses of AGE and TGF-beta, compared with the non-diabetic BALB/cA mouse. METHODS: The urinary albumin/creatinine ratio (ACR), body weight (BW), fasting and casual blood glucose, blood haemoglobin A(1c) (HbA(1c)), creatinine clearance (Ccr) and blood pressure were measured for phenotypic characterisation. The pathological changes of glomeruli were evaluated by light microscopy, immunofluorescence and electron microscopy. AGE and TGF-beta accumulation were evaluated by immunoperoxidase staining. RESULTS: The mean levels of ACR, casual blood glucose, blood HbA(1c) and Ccr in KK-A(y)/Ta mice were higher than those in age-matched non-diabetic BALB/cA mice after 12 weeks of age. There were no significant changes in the levels of systemic blood pressure among all groups. The pathological changes of glomeruli in KK-A(y)/Ta mice were consistent with those in the early stage of human diabetic nephropathy. AGE and TGF-beta protein appeared to be localised in the glomerular mesangial matrices. CONCLUSION: It appears that KK-A(y)/Ta mice, especially in terms of histopathological findings, are a suitable animal model for the early stage of type 2 diabetic nephropathy.

Animals↗

PubMed2006

Sex differences in the basolateral amygdala: the extracellular levels of serotonin and dopamine, and their responses to restraint stress in rats.

The sex difference in the emotional response to stress suggests a sex-specific stress response in the amygdala. To examine the sex difference in extracellular levels of serotonin (5HT) and dopamine (DA) in the basolateral amygdala (BLA) and their responses to restraint stress, in vivo microdialysis studies were performed in male and female rats. In experiment I, dialysates were collected from the BLA at 15-min intervals under the freely moving condition. Mean extracellular levels of 5HT or DA in the BLA were higher in male rats than in female rats. In experiment II, rats were subjected to restraint stress for 60 min to examine the stress response of 5HT or DA levels. Although restraint stress significantly increased extracellular 5HT levels in both sexes of rats, female rats showed a greater response than male rats. Moreover, restraint stress significantly increased extracellular DA levels in female rats, but not in male rats. In experiment III, rats were subjected to restraint stress for 30 min to examine behavioral responses to restraint stress. Although no sex difference was observed in the number of audible vocalizations, male rats defecated a larger number of fecal pellets than female rats. In experiment IV, rats were tested for freezing behavior to examine contextual fear responses. Conditioned male rats showed a longer freezing time than conditioned female rats. We found sex differences in the extracellular levels of 5HT and DA in the BLA and their responses to restraint stress, which may be involved in the sex-specific emotional response to stress in rats.

Aggression↗

PubMed2005

Testing various herbs for antithrombotic effect.

OBJECTIVE: Prevention of arterial thrombotic diseases has high priority in developed countries. Because people who eat inappropriate food are prone to thrombotic events, regular intake of an antithrombotic diet may offer a convenient and effective way of prevention. The aim of the present study was to find herbs that have antithrombotic effects. METHODS: Herbs were crushed and centrifuged and the juice obtained was filtered. The effect of filtrate on platelet-rich thrombus formation was assessed by a shear-induced in vitro platelet function test (hemostatometry). Filtrates showing significant antithrombotic activity were further assessed by using a laser-induced in vivo thrombosis test in mice. The effect of orally administered herb filtrates on flow-mediated vasodilation was also measured. RESULTS: Common thyme and rosemary showed significant antithrombotic activity in vitro and in vivo. Neither herb affected flow-mediated vasodilation. CONCLUSION: Some herbs possess antithrombotic effects in experimental models of thrombosis. The mechanism of the antithrombotic effect of common thyme and rosemary may involve a direct inhibitory effect on platelets.

Animals↗

PubMed2004

An onion variety has natural antithrombotic effect as assessed by thrombosis/thrombolysis models in rodents.

INTRODUCTION: Prevention of arterial thrombotic diseases has a high priority in developed countries. As inappropriate diet has been shown to be an important risk factor for thrombotic events, regular antithrombotic diet may offer a convenient and effective way of prevention. The aim of the present study was to test onion extracts for antithrombotic effect and to identify the effective varieties in Allium cepa. MATERIALS AND METHODS: A shear-induced platelet function test (haemostatometry) was used to screen for antithrombotic potential. Onion extracts showing significant antithrombotic activity in vitro were further assessed in vivo by using a laser-induced thrombosis test in mice. RESULTS AND CONCLUSIONS: An onion variety, Toyohira, showed significant antithrombotic activity both in vitro and in vivo. Toyohira showed thrombolytic activity in addition to the antiplatelet effect. Superkitamomiji, 2935A, and K83211 showed only thrombolytic activity. Quercetin, the richest flavonoid in onion, was measured, but no correlation was found between quercetin content and antithrombotic activity. It is concluded that onion A. cepa can be classified into varieties with or without antithrombotic and thrombolytic effects. This should be taken into account in future population studies on the antithrombotic effects of vegetables.

Animals↗