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We report a case of rupture of a synchronous metastatic liver tumor secondary to a thymoma. A 56-year-old woman was referred to our hospital with acute abdomen. Computed tomography (CT) revealed a 10 cm diameter tumor in the left lateral segment of the liver, together with ascites, which was suggestive of intra-abdominal bleeding. She was in stable condition and hemostasis was confirmed by angiography. CT also revealed a mass in the anterior mediastinum. Elective laparoscopic left lateral segmentectomy was performed to make a pathological diagnosis and for radical resection. No peritoneal dissemination was observed and the liver tumor was curatively resected. The patient subsequently underwent thymectomy. The pathological diagnoses were thymoma with the liver metastasis. Currently, at 30 months post-treatment, she has had no tumor recurrence. Rupture of a metastatic liver tumor secondary to a thymoma is a rare condition; careful preoperative management and aggressive treatment might improve the patient's prognosis. [ABSTRACT FROM AUTHOR]

Proinsulinoma is a subtype of insulinoma that is surgically curable, but localization can be difficult as these tumors are typically too small to be visualized by imaging. We report the case of a 53-year-old woman referred to our hospital with dizziness and headache. Her blood glucose level was 46 mg/dl and Whipple's triad was present. Although her immunoreactive insulin level during hypoglycemia was in the normal range (5.0 μU/ml), the proinsulin level was elevated (408 pmol/l). Imaging examinations showed no evidence of pancreatic tumor. A preoperative selective arterial calcium injection (SACI) test showed excessive insulin secretion in the splenic artery region, which localized the proinsulinoma to the body or tail of the pancreas, and laparoscopic spleen-preserving distal pancreatectomy was performed. Intraoperative SACI test performed after tumor removal did not show excessive insulin secretion. The intraoperative SACI test appears to be useful for localization and for confirming complete resection of proinsulinoma. [ABSTRACT FROM AUTHOR]

This work demonstrated that the targeting of a polytopic membrane protein to the inner envelope membrane of chloroplasts in vivo involves multiple transmembrane segments including the indispensable transmembrane segment.The inner envelope membrane (IEM) of the chloroplast plays crucial roles in forming an osmotic barrier and controlling metabolite exchange between the organelle and the cytosol. The IEM therefore harbours a number of membrane proteins and requires the import and integration of these nuclear-encoded proteins for its biogenesis. Recent studies have demonstrated that the transmembrane segment of single-spanning IEM proteins plays key roles in determining their IEM localization. However, few studies have focused on the molecular mechanisms by which polytopic membrane proteins are targeted to the IEM. In this study, we investigated the targeting mechanism of polytopic IEM proteins using the protein Cor413im1 as a model substrate. Cor413im1 does not utilize a soluble intermediate for its targeting to the IEM. Furthermore, we show that the putative fifth transmembrane segment of Cor413im1 is necessary for its targeting to the IEM. The C-terminal portion containing this transmembrane segment is also able to deliver Cor413im1 protein to the IEM. However, the fifth transmembrane segment of Cor413im1 itself is insufficient to target a fusion protein to the IEM. These data suggest that the targeting of polytopic membrane proteins to the chloroplast IEM in vivo involves multiple transmembrane segments and that chloroplasts have evolved a unique mechanism for the integration of polytopic proteins to the IEM. [ABSTRACT FROM PUBLISHER]

The article presents an in vitro fluorescent analysis on the lipoprotein import of chloroplasts. It states that a green fluorescent protein (GFP)-fused precursor and a fluorescent dye-labeled one were used to observe protein localization in living cells. It further claims that while GFP and other fluorescent proteins are valuable probes, the application of fluorescent proteins to the in vitro protein transport system does not take any benefits of their fluorescence.

The translocons at the outer envelope membrane of chloroplasts (TOCs) initiate the import of thousands of nucleus-encoded proteins into the organelle. The identification of structurally and functionally distinct TOC complexes has led to the hypothesis that the translocons constitute different import pathways that are required to coordinate the import of sets of proteins whose expression varies in response to organelle biogenesis and physiological adaptation. To test this hypothesis, we examined the molecular basis for distinct TOC pathways by analyzing the functional diversification among the Toc159 family of TOC receptors. We demonstrate that the N-terminal A-domains of the Toc159 receptors regulate their selectivity for preprotein binding. Furthermore, the in vivo function of the two major Toc159 family members (atToc159 and atToc132) can be largely switched by swapping their A-domains in transgenic Arabidopsis thaliana. On the basis of these results, we propose that the A-domains of the Toc159 receptors are major determinants of distinct pathways for protein import into chloroplasts. [ABSTRACT FROM AUTHOR]

The article reports on the alternative processing of Arabidopsis HSp70 precursors during protein import into chloroplasts. An in vitro protein import assay was employed to determine the localization of three Arabidopsis homolog of Hsp70-IAP. The author notes that organelle-free processing assays revealed that the larger processes forms of both AtHsp70-6 and AtHsp70-7 were cleaved by stromal processing peptidase.

Background. Renal cell carcinoma (RCC) frequently occurs in patients with long-term dialysis. Long-term dialysis causes distinctive pathological changes in the kidney, which is known as acquired cystic disease of the kidney (ACDK). It is of great interest to know whether RCCs occurring in the dialytic kidneys harbour the same or similar mutations of the von Hippel–Lindau (VHL) gene as conventional dialysis-unrelated clear cell RCCs so often do. [ABSTRACT FROM PUBLISHER]

Background: Dexamethasone, a synthetic glucocorticoid, has clinical benefit in patients with hormone-refractory prostate cancer (HRPC), but the mechanisms responsible for its effects are unknown. The nuclear factor-kappaB (NF-kappaB)-dependent cytokine interleukin (IL) 6 (IL-6) is thought to stimulate growth of HRPC. Because dexamethasone interferes with NF-kappaB activation, we determined whether dexamethasone inhibits prostate cancer growth by working through the glucocorticoid receptor (GR) to interfere with NF-kappaB-IL-6 pathway.Methods: Three human prostate cancer cell lines (DU145, PC-3, and LNCaP) were assessed for GR expression and responsiveness to dexamethasone. Levels of GR, NF-kappaB, and the cytoplasmic NF-kappB inhibitor IkappaBalpha were determined by western blotting and of IL-6 by enzyme immunoassay. The subcellular localization of NF-kappaB was analyzed by immunofluorescence. The effects of dexamethasone (thrice weekly injections of 1 microg/mouse) on DU145 xenografts in nude and severe combined immunodeficient (SCID) mice were evaluated. GR expression in human prostate cancers was assessed by immunohistochemistry. All statistical tests were two-sided.Results: Dexamethasone dose dependently decreased GR levels and inhibited the growth of DU145 and PC-3 but not LNCaP cells (DU145 cells, P< .001; PC-3 cells, P = .009). Dexamethasone increased IkappaBalpha protein levels and the cytosolic accumulation of NF-kappaB in DU145 cells and decreased secreted IL-6 levels to 37 pg/mL (95% confidence interval [CI] = 33 pg/mL to 41 pg/mL), compared with 164 pg/mL (95% CI = 162 pg/mL to 166 pg/mL) secreted by ethanol-treated control cells. Dexamethasone inhibited the growth of DU145 xenografts in nude (P = .006) and SCID (P = .026) mice without affecting GR levels. Eight of 16 human prostate cancers expressed GR at high levels (>or=30% GR-positive cells).Conclusion: Dexamethasone inhibited the growth of GR-positive cancers, possibly through the disruption of the NF-kappaB-IL-6 pathway. [ABSTRACT FROM AUTHOR]