Yoshihiro Hayashi

Vinculin: Its Possible Use as a Marker of Normal Collecting Ducts and Renal Neoplasms with Collecting Duct System Phenotype

Vinculin is a cytoskeletal protein associated with membrane actin-filament-attachment sites of cell-cell and cell-matrix adherens-type junctions. In this article, we examine the expression of vinculin to elucidate its role in human renal neoplasms. We reviewed surgically resected specimens and selected available tissue from 79 renal tumors in 78 patients. There were 55 men and 23 women. Their mean age was 61 years and the mean size of the renal tumors was 6.1 cm. All renal tumors were examined by immunohistochemistry using a monoclonal antibody against vinculin. Overall, 17 (21.5%) renal tumor samples reacted with vinculin. The positive ratio in various types of renal tumors was as follows: conventional-type (clear cell), 0/54; papillary-type, 5/12; chromophobe-type, 5/5; sarcomatoid-type, 3/4; collecting duct carcinoma, 3/3; and oncocytoma, 1/1. The positive rate of conventional-type renal cell carcinomas (RCCs) is significantly different from that of other renal tumors (P < .01). Normal kidney, conventional, and papillary-type RCCs exhibited positive signals in Western blot analysis. These results suggest that vinculin may serve as a useful marker of renal neoplasms with collecting duct system phenotype such as chromophobe-type RCC.

Appearance of denuded hepatic stellate cells and their subsequent myofibroblast-like transformation during the early stage of biliary fibrosis in the rat

To investigate the early in vivo response of hepatic stellate cells in biliary fibrosis, we examined rat livers during the first 7 days after bile duct ligation using light microscopy, immunohistochemistry, electron microscopy, and immunoelectron microscopy. At day 1 after bile duct ligation, α-smooth muscle actin-positive fibroblasts appeared and then increased in number around the proliferating bile ductules. With time, the destruction of the external limiting plate became accentuated because of the invasion of the proliferating bile ductules and periductural fibrosis. At day 7, stromal cells containing fat droplets appeared in the fibrous tissue adjacent to the periportal parenchyma; these are termed denuded hepatic stellate cells. In the fibrous tissue disconnected from the liver parenchyma, the denuded hepatic stellate cells were replaced by myofibroblast-like cells. Meanwhile, the expression of transforming growth factor-β1 on biliary epithelial cells increased. These results indicate the dual origin of myofibroblasts in experimental biliary fibrosis, the periductural and periductal fibroblasts in the initial stage, and the denuded hepatic stellate cells in the subsequent stage. These two types of stromal cells may undergo myofibroblastic transformation by the transforming growth factor-β1 secreted by the proliferating biliary epithelial cells.

Invasive micropapillary carcinoma of the colon: an immunohistochemical study

Invasive micropapillary carcinoma has recently been reported in various anatomic sites. In this article, we report a case of micropapillary carcinoma of the sigmoid colon. A 70-year-old Japanese woman presented with bloody stool for 2 months. Detailed examination disclosed ulcerative and localized tumor in the sigmoid colon. Histological examination of the colon tumor showed a combination of conventional adenocarcinoma (60%) and micropapillary carcinoma (40%). Immunohistochemically, micropapillary carcinoma cells were positive for cytokeratin (CK) 20, carcinoembryonic antigen, and CA125, but negative for CK7, thyroid transcription factor-1, surfactant apoprotein A, estrogen receptor, and progesterone receptor. Additionally, the immunohistochemistry of epithelial membrane antigen revealed reverse polarity of neoplastic cells. Results of conventional adenocarcinoma were basically identical to those of micropapillary carcinoma. In the stroma of both conventional adenocarcinoma and micropapillary carcinoma, many myofibroblasts were present and CD34-positive stromal cells were absent. Finally, we report the fourth case of micropapillary carcinoma arising in the colon. Immunohistochemical results of CK7(−)/CK20(+) strongly suggest the colon as a primary site of micropapillary carcinoma. Additionally, micropapillary carcinoma of the colon may cause a similar stromal reaction to conventional adenocarcinoma of the colon.

Pitavastatin ameliorates severe hepatic steatosis in aromatase-deficient (Ar-/-) mice

Tamoxifen is a potent antagonist of estrogen, and hepatic steatosis is a frequent complication in adjuvant tamoxifen for breast cancer. Impaired hepatic FA β-oxidation in peroxisomes, microsomes, and mitochondria results in progression of massive hepatic steatosis in estrogen deficiency. This impairment, although latent, is potentially serious: About 3% of the general population in the United States is now suffering from nonalcoholic steatohepatitis associated with obesity and hyperlipidemia. Therefore, in the present study we tried to restore impaired hepatic FA β-oxidation by administering a novel statin, pitavastatin, to aromatase-deficient (Ar−/−) mice defective in intrinsic estrogen synthesis. Northern blot analysis of Ar−/− mice liver revealed a significant restoration of mRNA expression of essential enzymes involved in FA β-oxidation such as very long fatty acyl-CoA synthetase in peroxisome, peroxisomal fatty acyl-CoA oxidase, and medium-chain acyl-CoA dehydrogenase. Severe hepatic steatosis observed in Ar−/− mice substantially regressed. Consistent findings were obtained in the in vitro assays of FA β-oxidation activity. These findings demonstrate that pitavastatin is capable of restoring impaired FA β-oxidation in vivo via the peroxisome proliferator-activated receptor-α-mediated signaling pathway and is potent enough to ameliorate severe hepatic steatosis in mice deficient in intrinsic estrogen.

Low-grade tubular-mucinous renal neoplasm with neuroendocrine differentiation: a histological, immunohistochemical and ultrastructural study.

Low‐grade tubular‐mucinous renal neoplasm (LGTMRN) was recently established as a distinct carcinoma classification. A 70‐year‐old, female traffic accident victim underwent a detailed examination that disclosed a huge mass in the lower pole of the left kidney. The patient underwent a nephrectomy based on a diagnosis of renal tumor. Macroscopically, the tumor was well demarcated and a whitish color with focal hemorrhage. Histological examination showed that tumor cells proliferated through tubular, trabecular, and solid growth patterns in the mucinous background. Focally, foci of clear cells or the proliferation of spindle cells was also observed. Nuclei were generally round and uniform in size. No abnormal mitotic figures were identified. Immunohistochemically, tumor cells were diffusely positive for AE1/AE3, vimentin and chromogranin A, and focally positive for cytokeratin (CK) 18, CK19, Ulex europaeus agglutinin‐1, epithelial membrane antigen, neuron‐specific enolase (NSE), CD9 and CD57. Ultrastructurally, tumor cells contained a moderate number of mitochondria, rough endoplasmic reticulum and dense‐core granules. No renin granules or glycogen were observed. Microvilli were focally seen. Our results render further evidence that LGTMRN is a distinct entity from the hitherto established renal neoplasms. Foci of clear cells and neuroendocrine differentiation should be added to the histological spectrum of LGTMRN.

Mesangial cell activation in the collagenofibrotic glomerulonephropathy

Abstract Collagenofibrotic glomerulonephropathy is a new disease entity of unknown pathogenesis, which is characterized by the deposition of type III collagen within the mesangial matrix. We have investigated a case in which many mesangial cells in the type III collagen-deposited glomeruli were α-smooth muscle actin (ASMA) positive and showed an increase of subplasmalemmal filaments, indicating the activation and myofibroblastic transformation. It is suggested that the activated mesangial cells may synthesize the type III collagen deposited in the subendothelial space and mesangial matrix.

Estrogen deficiency results in enhanced expression of Smoothened of the Hedgehog signaling in the thymus and affects thymocyte development

Aromatase is an essential enzyme for estrogen synthesis. We investigated the role of estrogen in thymocyte development using aromatase-deficient (ArKO) mice. Like its role as a regulator of bone metabolism through regulating osteoprotegerin (OPG) production, estrogen is involved in the processes of thymocyte development although aromatase mRNA was not detectable in the thymus. Thymic regression and reduced cellularity were evident in ArKO mice. The major difficulties in thymocyte development of ArKO mice were observed during the CD44+ CD25- stage at the cortico-medullary junction and during the CD44- CD25- stage at the subcapsular region where the estrogen receptor was expressed in the stromal cells. The proportion of thymocytes during the CD44+ CD25- stage was reduced. The progression of CD44- CD25+ cells to the CD44- CD25- stage was accelerated in ArKO mice possibly due to insufficient osteoprotegerin production in estrogen-deficiency. However, the expression of Smoothened of the Hedgehog signaling was enhanced in CD4- CD8- double negative cells. This enhancement may result in impaired progression of CD44- CD25- cells to the CD4+ CD8+ double positive stage and impaired proliferation of CD4+ CD8+ double positive cells since Smoothened (Smo) is known to arrest cells as non-proliferating cells. This could be the reason why the proportion of CD3+ TCRbeta(high) cells during the late phase of thymocyte maturation was reduced in ArKO mice. From these observations, we propose that estrogen supports thymocyte development and maturation at many stages through many regulatory pathways including the sonic hedgehog- and the osteoprotegerin ligand (OPGL)-mediated signaling.

Vinculin: a novel marker for quiescent and activated hepatic stellate cells in human and rat livers

In liver injuries, the quiescent hepatic stellate cells (HSCs) promptly change to activated HSCs, which are easily identified by the intense immunoreactivity for α-smooth muscle actin. However, reproducible markers for quiescent HSCs in formalin-fixed, paraffin-embedded liver tissue sections have not yet been reported. We immunohistochemically examined the expression of vinculin, one major protein of dense plaques, on cultured LI90 cells and on HSCs in normal and diseased human and rat livers. In cultured LI90 cells, vinculin appeared as small linear patches. Although vinculin was consistently negative in the routine liver tissue sections, an antigen retrieval technique using microwave oven heating yielded excellent effects. Using this technique, the formalin-fixed, paraffin-embedded human and rat normal liver tissue sections showed the vinculin immunoreactivity along the sinusoidal wall. Immunoelectron microscopic observation of hepatic parenchyma demonstrated that the vinculin was exclusively expressed in quiescent HSCs. In fetal rat livers, vinculin-positive quiescent HSCs gradually increased in number with gestation. In diseased livers the activated HSCs showed more intense immunoreaction for vinculin. These results indicate that, using microwave pretreatment, vinculin is expressed in quiescent and activated HSCs in routinely processed liver tissue sections. It could allow us to evaluate the development and distribution of quiescent HSCs and to examine the relationship between quiescent and activated HSCs.

Anaplastic carcinoma of the pancreas with rhabdoid features

The malignant rhabdoid tumor (MRT) is histologically characterized by the invasive proliferation of polygonal to ovoid cells with abundant eosinophilic cytoplasm and eccentric vesicular nuclei with a prominent nucleolus. MRT frequently occurs in the kidney, but may also arise in other organs. However, MRT should be strictly distinguished from carcinomas with rhabdoid features. A post‐mortem examination of a 68‐year‐old woman found an anaplastic carcinoma of the pancreas with rhabdoid features displaying extensive invasion into the neighboring tissues. To the best of our knowledge, this is the first case of a pancreatic tumor with rhabdoid features. Pathologists should consider that carcinomas showing rhabdoid features may also appear in the pancreas. As pancreatic tumors with rhabdoid features have characteristic histopathological features and poor prognosis compared to other pancreatic tumors, careful histopathological differential diagnosis is important.

CD34 expression as a novel marker of transformed mesangial cells in biopsied glomerular diseases.

CD34 is a marker of haematopoietic progenitor cells, stromal precursors, vascular endothelial cells, and a variety of stromal tumour cells. This immunohistochemical study examined the CD34 expression of glomerular mesangial cells in normal and diseased glomeruli and compared it with the staining patterns of α‐smooth muscle actin (ASMA), as a transformed mesangial cell marker, and CD31, as an endothelial cell marker. In addition, the CD34 and ASMA expression of mesangial cells in various glomerulonephritis and the relationship of the immunostaining intensity to the severity of IgA nephropathy were semiquantitatively evaluated. In normal glomeruli, all cell types were negative for CD34, but in glomeruli in mesangial proliferative glomerulonephritis, CD34 was expressed exclusively in mesangial cells, corresponding to ASMA expression. The dendritic and scattered staining pattern, the mesangial location of positive signals, and the enhanced expression were clearly different from CD31 expression in diseased glomeruli. In comparison with normal controls, the grade of immunostaining for CD34 (CD34 INDEX) in mesangial proliferative glomerular diseases was higher than that of ASMA (ASMA INDEX). With the severity of glomerulonephritis, the CD34 INDEX gradually increased. These studies indicate that CD34 is a useful marker of mesangial transformation and that immunohistochemical examination with the anti‐CD34 antibody is useful for the diagnosis and stage determination of glomerular diseases. Copyright