Bafilomycin A1, a specific inhibitor of V-type H+-ATPases,inhibits the acidification of endocytic structures and inhibits horseradish peroxidase uptake in isolated rat sinusoidal endothelial cells

Abstract: The role of vacuolar type H+-ATPases (v-ATPases) and pH gradient between the endocytic compartments and cytoplasm in the endocytosis of horseradish peroxidase, a mannose-terminated glycoprotein, was investigated morphologically in isolated rat sinusoidal endothelial cells. Toward this purpose, a specific inhibitor of v-ATPases, bafilomycin A1, was used to inhibit v-ATPases in the vacuolar system. Uptake of horseradish peroxidase was examined by electron microscopy. Fluorescent staining by acridine orange showed that bafilomycin A1 inhibited the acidification of the endocytic compartments. Horseradish peroxidase was taken up via mannose receptors and was distributed in the endocytic structures in the isolated sinusoidal endothelial cells. Uptake of horseradish peroxidase was significantly inhibited by bafilomycin A1, and this finding was confirmed by morphometrical analysis. These results suggest that: a) v-ATPases are necessary for acidification of the endocytic compartments in the sinusoidal endothelial cells and b) the pH gradient between the endocytic compartments and the cytoplasm that is generated by v-ATPases is necessary for the receptor-mediated endocytosis of a mannose-terminated glycoprotein, horseradish peroxidase.     

Two cases of disseminated Trichosporon beigelii infection treated with combination antifungal therapy

Two patients with acute leukemia in whom disseminated Trichosporon beigelii infection developed are reported. The T. beigelii infection developed in the first patient while he was receiving 5-fluorocytosine. He was treated with amphotericin B in addition to 5-fluorocytosine. Despite the continued antifungal therapy, multiple organs were invaded by the organisms at autopsy. The second patient was treated with miconazole and norfloxacin. Although this combination antifungal therapy seemed to be effective, this patient required splenectomy for cure of the infection.     

Potent inhibition by star fruit of human cytochrome P450 3A (CYP3A) activity.

There has been very limited information on the capacities of tropical fruits to inhibit human cytochrome P450 3A (CYP3A) activity. Thus, the inhibitory effects of tropical fruits on midazolam 1'-hydroxylase activity of CYP3A in human liver microsomes were evaluated. Eight tropical fruits such as common papaw, dragon fruit, kiwi fruit, mango, passion fruit, pomegranate, rambutan, and star fruit were tested. We also examined the inhibition of CYP3A activity by grapefruit (white) and Valencia orange as controls. The juice of star fruit showed the most potent inhibition of CYP3A. The addition of a star fruit juice (5.0%, v/v) resulted in the almost complete inhibition of midazolam 1'-hydroxylase activity (residual activity of 0.1%). In the case of grape-fruit, the residual activity was 14.7%. The inhibition depended on the amount of fruit juice added to the incubation mixture (0.2-6.0%, v/v). The elongation of the preincubation period of a juice from star fruit (1.25 or 2.5%, v/v) with the microsomal fraction did not alter the CYP3A inhibition, suggesting that the star fruit did not contain a mechanism-based inhibitor. Thus, we discovered filtered extracts of star fruit juice to be inhibitors of human CYP3A activity in vitro.     

Basic FGF and Ki-67 proteins useful for immunohistological diagnostic evaluations in malignant solitary fibrous tumor

Solitary fibrous tumor (SFT) is an uncommon soft tissue tumor initially reported in the pleura but recently described in other sites in the body. Morphological distinction between benign and malignant SFT is often difficult. An immunohistochemical study was performed in pleural and extrapleural sites. The aim of this study was to determine if an immunohistochemical method is helpful in distinguishing benign SFT from malignant SFT, and providing valid information to predict the prognosis associated with malignant SFT. Twenty-four cases of benign (14 patients) and malignant (10 patients) SFT in the pleura, pelvic space, prostate and other sites of soft tissue were analyzed. Tumors from 10 patients were diagnosed as malignant on the basis of markedly increased cellularity, mitotic activity (>4/10 high-power fields), nuclear pleomorphism and areas of necrosis. Immunohistochemically, we found a mean basic fibroblast growth factor (bFGF) labeling index of 48.67% (48.67 +/- 8.52%) for benign SFT and 74.5% (74.5 +/- 6.92%) for malignant SFT (P < 0.05). We also found a mean Ki-67 labeling index of 1.9% (1.9 +/- 0.43%) for benign SFT and 6.11% (6.11 +/- 1.05%) for malignant SFT (P < 0.05). Our results suggest that bFGF and Ki-67 are diagnostically relevant to the evaluation of malignant SFT and these proteins are thought to be potentially useful markers for prognosis of SFT.     

Prepro-thyrotropin releasing hormone 178-199 immunoreactivity is altered in the hypothalamus of the Wistar–Kyoto strain of rat

The rat prepro-thyrotropin releasing hormone (TRH) 178-199 is derived from prepro-TRH by the actions of the endopeptidases, prohormone convertase 1 (PC1) and PC2. PPTRH 178-199 attenuates the synthesis and secretion of adrenocorticotropic hormone (ACTH) from the anterior pituitary both in vitro and in vivo, suggesting an inhibitory action on hypothalamic–pituitary–adrenal (HPA) axis function. This peptide also acts centrally to increase activity and decrease anxiety related behaviors. To elucidate the involvement of this peptide in these functions, we have compared the expression of PPTRH 178-199, PPTRH mRNA, and PC1 and PC2 mRNAs in the Wistar–Kyoto (WKY) and Wistar strains of rat. WKY rats have been shown to possess neuroendocrine abnormalities (HPA hyper-activity) and hyper-emotional behavioral characteristics. Immunohistochemical analysis of PPTRH 178-199 demonstrated significant strain differences in the paraventricular nucleus (PVN) of the hypothalamus and the parastrial nucleus (PSN). WKY rats had significantly greater numbers of immunoreactive (IR) cell body profiles (P<0.0005) than Wistar rats in the PVN and a significantly lower fiber density (P<0.002) in the PSN. Levels of PPTRH, PC1, and PC2 mRNA were not different between strains in any brain region examined. These data suggest that altered levels of PPTRH 178-199 in WKY rats could cause, at least in part, the hyper-activity of the HPA axis and the hyper-emotional behavioral characteristics seen in this rat strain. Such data fit with the hypothesis that PPTRH 178-199 is involved in the regulation of the HPA axis and behavior.     

A case of an epithelial cyst arising in the intrapancreatic accessory spleen]

A 59-year old woman was admitted to our hospital for further examination of a cystic lesion detected in the tail of the pancreas. Imaging studies showed a 35-mm-diameter cystic lesion with septa and mural nodule at the same site. The mural nodule of the cyst was thick and was enhanced. Partial resection of the tail pancreas was performed with a preoperative diagnosis of pancreatic cystic tumor. The resected specimen showed mulitlobular cyst. Histologically, the internal surface of the cyst was covered with stratified squamous cells and the mural nodule of the cyst was spleen tissue. The final diagnosis was an epithelial cyst derived from an accessory spleen in the pancreas.     

SQUAMOUS DYSPLASIA AND CARCINOMA IN SITU OF THE ESOPHAGUS IN JAPAN

In this paper, the authors review recent topics of interest in relation to squamous dysplasia and squamous cell carcinoma in situ in Japan, and also the differences in diagnostic criteria for squamous cell carcinoma in situ between Japanese and Western pathologists. Photomicrographs of high‐grade squamous dysplasia in Western textbooks of surgical pathology are judged in Japan to be squamous cell carcinoma in situ. Squamous cell carcinoma in situ can be histologically subdivided by the appearance of the basement membrane into the simple replacement type, showing a linear pattern, and the bulky outgrowth type, showing a wavy pattern. Squamous cell carcinoma in situ may also be classified into a total layer type, in which the entire epithelium is replaced by tumor cells, and a basal layer type in which the basal half is replaced by tumor cells. It is frequently observed that minute squamous cell carcinomas of the basal layer type, but not the total layer type, show signs of early stromal invasion into the lamina propria mucosae. These histologic findings strongly indicate that the basal layer type is not low‐grade dysplasia but squamous cell carcinoma in situ.     

Functional immaturity of cord blood monocytes as detected by impaired response to hepatocyte growth factor

BACKGROUND: Monocytes as antigen-presenting cells play an important role in host defense and transplantation. However, there are little reports on cord blood monocytes, and the role of monocytes in cord blood transplantation is largely unknown. METHODS AND RESULTS: There are several cytokines affecting monocyte function. These include interferon-gamma, interleukin-4, interleukin-10, granulocyte macrophage-colony stimulating factor and hepatocyte growth factor (HGF). We investigated the effect of these cytokines on antigen-presenting capacity (APC) of cord and adult blood monocytes. Using either mononuclear cells or purified CD4+ T cells as responder cells, HGF enhanced APC of adult monocytes most effectively among these cytokines. In contrast, cord blood monocytes failed to respond to HGF. As HLA, costimulatory and adhesion molecules may affect APC function, we examined these antigens of monocytes following HGF stimulation. The HGF upregulated integrin alpha5 subunit (CD49e) and intercellular adhesion molecule-1 (CD54) was expressed in adult blood monocytes, but not in cord blood. In kinetic studies, HGF downregulated c-met protein/HGF receptor expression of adult monocytes in lower concentrations and at shorter incubation time as compared with that of cord blood. CONCLUSIONS: The results suggest that impaired response of cord blood monocytes to HGF may be responsible, in large part, for their functional immaturity.     

Solid and papillary tumor of the pancreas complicating agenesis of the dorsal pancreas

We report the first documented case of a solid and papillary tumor of the pancreas (SPT) complicating agenesis of the dorsal pancreas. A 28‐year‐old female patient was referred to our hospital for a pancreatic tumor detected at a local hospital. The laboratory findings were all within normal limits. Diagnostic images revealed absence of the dorsal pancreas and the presence of a tumor located in the head of the pancreas. The tumor was solid, well demarcated, noncalcified, and hypovascular. Fine‐needle aspiration cytology revealed that larger cell clumps often had a branching papillary appearance, with multiple layers of tumor cells surrounding central vascular stalks; a preoperative diagnosis of SPT was made. At surgery, on February 10, 1999, the tumor was found to have clear margins, and it showed no signs of direct invasion of adjacent structures. No metastases were found in the liver or the local lymph nodes. Accordingly, partial resection of the pancreas, including the entire tumor, was performed, and, thus, almost the entire head of the pancreas could be saved. Microscopic examination of the resected specimen yielded findings compatible with SPT. No recurrences, and no impairment of pancreatic endocrine or exocrine function have been noted since the operation.