CiteULike: jyuh's Shibata

Tractable Cre-lox system for stochastic alteration of genes in mice

Ashleigh Miller — 2008-02-29T01:36:32-00:00

Nature Methods, Vol. 5, No. 3. (10 February 2008), pp. 227-229.

Genetically distinct and clinically relevant classification of hepatocellular carcinoma: putative therapeutic targets.

H Katoh — 2008-01-25T02:03:17-00:00

Gastroenterology, Vol. 133, No. 5. (November 2007), pp. 1475-1486.

BACKGROUND & AIMS: The biological aggressiveness of hepatocellular carcinoma (HCC) and the lack of optimal therapeutic strategies have rendered the disease a major challenge. Highly heterogeneous genetic alteration profiles of HCC have made it difficult to identify effective tailor-made molecular therapeutic targets. Therefore, classification of HCC into genetically homogeneous subclasses would be of great worth to develop novel therapeutic strategies. METHODS: We clarified genome-scale chromosomal copy number alteration profiles and mutational statuses of p53 and beta-catenin in 87 HCC tumors. We investigated the possibility that HCC might be classifiable into a number of homogeneous subclasses based solely on their genetic alteration profiles. We also explored putative molecular therapeutic targets specific for each HCC subgroup. RESULTS: Unsupervised hierarchical cluster analysis based on chromosomal alteration profiles suggested that HCCs with heterogeneous genetic backgrounds are divisible into homogeneous subclasses that are highly associated with a range of clinicopathologic features of the tumors and moreover with clinical outcomes of the patients (P < .05). These genetically homogeneous subclasses could be characterized distinctively by pathognomonic chromosomal amplifications (eg, c-Myc-induced HCC, 6p/1q-amplified HCC, and 17q-amplified HCC). An in vitro experiment raised a possibility that Rapamycin would significantly inhibit the proliferative activities of HCCs with 17q amplification. CONCLUSIONS: HCC is composed of several genetically homogeneous subclasses, each of which harbors characteristic genetic alterations that can be putative tailor-made molecular therapeutic targets for HCCs with specific genetic backgrounds. Our results offer an opportunity for developing novel individualized therapeutic modalities for distinctive genome types of HCC.

Podocyte as the target for aldosterone: roles of oxidative stress and Sgk1.

S Shibata — 2008-01-21T01:49:06-00:00

Hypertension, Vol. 49, No. 2. (February 2007), pp. 355-364.

Accumulating evidence suggests that mineralocorticoid receptor blockade effectively reduces proteinuria in hypertensive patients. However, the mechanism of the antiproteinuric effect remains elusive. In this study, we investigated the effects of aldosterone on podocyte, a key player of the glomerular filtration barrier. Uninephrectomized rats were continuously infused with aldosterone and fed a high-salt diet. Aldosterone induced proteinuria progressively, associated with blood pressure elevation. Notably, gene expressions of podocyte-associated molecules nephrin and podocin were markedly decreased in aldosterone-infused rats at 2 weeks, with a gradual decrease thereafter. Immunohistochemical studies and electron microscopy confirmed the podocyte damage. Podocyte injury was accompanied by renal reduced nicotinamide-adenine dinucleotide phosphate oxidase activation, increased oxidative stress, and enhanced expression of aldosterone effector kinase Sgk1. Treatment with eplerenone, a selective aldosterone receptor blocker, almost completely prevented podocyte damage and proteinuria, with normalization of elevated reduced nicotinamide-adenine dinucleotide phosphate oxidase activity. In addition, proteinuria, podocyte damage, and Sgk1 upregulation were significantly alleviated by tempol, a membrane-permeable superoxide dismutase, suggesting the pathogenic role of oxidative stress. Although hydralazine treatment almost normalized blood pressure, it failed to improve proteinuria and podocyte damage. In cultured podocytes with consistent expression of mineralocorticoid receptor, aldosterone stimulated membrane translocation of reduced nicotinamide-adenine dinucleotide phosphate oxidase cytosolic components and oxidative stress generation in podocytes. Furthermore, aldosterone enhanced the expression of Sgk1, which was inhibited by mineralocorticoid receptor antagonist and tempol. In conclusion, podocytes are injured at the early stage in aldosterone-infused rats, resulting in the occurrence of proteinuria. Aldosterone can directly modulate podocyte function, possibly through the induction of oxidative stress and Sgk1.

Sensitivity and specificity of published strategies using urinary creatinine to identify incomplete 24-h urine collection.

K Murakami — 2008-01-20T04:23:22-00:00

Nutrition, Vol. 24, No. 1. (January 2008), pp. 16-22.

OBJECTIVE: Although urinary creatinine has been used to identify incomplete 24-h urine in numerous epidemiologic studies, information on its utility is limited. We examined the sensitivity and specificity of several strategies that use creatinine to identify incomplete urine using the p-aminobenzoic acid (PABA) check method as reference. METHODS: Subjects were 654 female Japanese dietetic students 18-22 y of age. A single 24-h urine sample was collected, with recording of the time of the start and end of the collection period and missing urine volume. Simultaneous administration of PABA was done to assess completeness. The sensitivity and specificity of five strategies derived from the literature that used creatinine to identify incomplete urine were calculated as the proportion of incomplete and complete urine correctly identified, respectively. RESULTS: A total of 7.6% of subjects was identified as having incomplete urine by PABA (PABA recovery <85%). This proportion significantly (P < 0.0001) decreased (to 5.5%) after considering self-reported collection time and missing urine volume in the calculation of total urine volume. The sensitivity and specificity of the strategy of Knuimann et al. (incomplete urine = <0.7 of [mmol urinary creatinine x 113]/[21 x kilograms of body weight]) were 0.47 and 0.99, respectively. The corresponding values of other strategies were 0.11-0.22 and 0.57-1.00, respectively. CONCLUSION: At least in well-motivated populations in which the proportion of incomplete urine is presumed to be small, the strategy of Knuimann et al. and consideration of the self-reported collection time and missing urine volume in the estimation of total volume may be useful.

In a type 2 diabetic nephropathy rat model, the improvement of obesity by a low calorie diet reduces oxidative/carbonyl stress and prevents diabetic nephropathy.

M Nangaku — 2007-10-23T09:11:32-00:00

Nephrol Dial Transplant, Vol. 20, No. 12. (December 2005), pp. 2661-2669.

BACKGROUND: The present study has been undertaken to unravel the critical factors involved in the progression of diabetic nephropathy (DN). METHODS: A unique type 2 diabetic rat model with a wide range of metabolic derangements and hypertension has been utilized, the spontaneously hypertensive/NIH-corpulent rat SHR/NDmcr-cp(cp/cp). It develops histologically evident glomerular injury and tubulointerstitial damage, including mesangial activation, podocyte injury, and inflammatory cell infiltration in the tubulointerstitium. RESULTS: A low calorie diet for 22 weeks significantly improves obesity, proteinuria and renal morphological alterations. The correction of renal injury is independent of blood pressure control. Obesity correction, although partial, normalizes the renal content of pentosidine taken as a marker of oxidative stress and advanced glycation end products (AGEs). This occurs despite the fact that, in this model, improvement of glucose control and hyperlipidaemia is limited. Proteinuria and body weight are highly correlated with renal pentosidine content, while proteinuria and body weight are also correlated with each other. Diabetic renal injury is thus inhibited by a low calorie diet with an attendant reduction of oxidative stress and AGE formation, despite sustained hypertension. CONCLUSION: The present findings suggest a direct role of obesity in the generation of a localized oxidative stress and AGE formation, directly responsible for DN.

Enhanced aldosterone signaling in the early nephropathy of rats with metabolic syndrome: possible contribution of fat-derived factors.

M Nagase — 2007-07-12T14:18:08-00:00

J Am Soc Nephrol, Vol. 17, No. 12. (December 2006), pp. 3438-3446.

Metabolic syndrome is an important risk factor for proteinuria and chronic kidney disease independent of diabetes and hypertension; however, the underlying mechanisms have not been elucidated. Aldosterone is implicated in target organ injury of obesity-related disorders. This study investigated the role of aldosterone in the early nephropathy of 17-wk-old SHR/NDmcr-cp, a rat model of metabolic syndrome. Proteinuria was prominent in SHR/NDmcr-cp compared with nonobese SHR, which was accompanied by podocyte injury as evidenced by foot process effacement, induction of desmin and attenuation of nephrin. Serum aldosterone level, renal and glomerular expressions of aldosterone effector kinase Sgk1, and oxidative stress markers all were elevated in SHR/NDmcr-cp. Mineralocorticoid receptors were expressed in glomerular podocytes. Eplerenone, a selective aldosterone blocker, effectively improved podocyte damage, proteinuria, Sgk1, and oxidant stress. An antioxidant tempol also alleviated podocyte impairment and proteinuria, along with inhibition of Sgk1. As for the mechanisms of aldosterone excess, visceral adipocytes that were isolated from SHR/NDmcr-cp secreted substances that stimulate aldosterone production in adrenocortical cells. The aldosterone-releasing activity of adipocytes was not inhibited by candesartan. Adipocytes from nonobese SHR did not show such activity. In conclusion, SHR/NDmcr-cp exhibit enhanced aldosterone signaling, podocyte injury, and proteinuria, which are ameliorated by eplerenone or tempol. The data also suggest that adipocyte-derived factors other than angiotensin II might contribute to the aldosterone excess of this model.

Rapid SNP diagnostics using asymmetric isothermal amplification and a new mismatch-suppression technology

Yasumasa Mitani — 2007-02-28T17:20:15-00:00

Nature Methods, Vol. 4, No. 3. (18 February 2007), pp. 257-262.

CYP2A6 gene deletion reduces oral cancer risk in betel quid chewers in Sri Lanka.

Z Topcu — 2007-07-10T04:28:22-00:00

Carcinogenesis, Vol. 23, No. 4. (April 2002), pp. 595-598.

We investigated the relationship between inter-individual difference in CYP2A6 genotype and susceptibility to oral cancer among habitual betel quid chewers in a Sri Lanka population. A total of 286 subjects showing oral malignant or premalignant lesions and 135 control subjects with no lesions were analyzed. The frequency of homozygotes for CYP2A6*4C mutation, a gene deletion type of polymorphism, was significantly lower in the case subjects than the controls. The odds ratio (OR) of the group homozygous for the deletion was significantly lower and calculated to be 0.14 (95% CI; 0.03-0.72). In the allelic base analysis, there was also a significant decrease in the OR of the deletion allele. Our data suggest that deficient CYP2A6 activity due to genetic polymorphism reduces oral cancer risk in betel quid chewers.