High linear-energy-transfer radiation can overcome radioresistance of glioma stem-like cells to low linear-energy-transfer radiation

Ionizing radiation is applied as the standard treatment for glioblastoma multiforme (GBM). However, radiotherapy remains merely palliative, not curative, because of the existence of glioma stem cells (GSCs), which are regarded as highly radioresistant to low linear-energy-transfer (LET) photons. Here we analyzed whether or not high-LET particles can overcome the radioresistance of GSCs. Glioma stem-like cells (GSLCs) were induced from the GBM cell line A172 in stem cell culture medium. The phenotypes of GSLCs and wild-type cells were confirmed using stem cell markers. These cells were irradiated with ⁶⁰Co gamma rays or reactor neutron beams. Under neutron-beam irradiation, high-LET proton particles can be produced through elastic scattering or nitrogen capture reaction. Radiosensitivity was assessed by a colony-forming assay, and the DNA double-strand breaks (DSBs) were assessed by a histone gamma-H2AX focus detection assay. In stem cell culture medium, GSLCs could form neurosphere-like cells and express neural stem cell markers (Sox2 and Musashi) abundantly in comparison with their parental cells. GSLCs were significantly more radioresistant to gamma rays than their parental cells, but neutron beams overcame this resistance. There were significantly fewer gamma-H2AX foci in the A172 GSLCs 24 h after irradiation with gamma rays than in their parental cultured cells, while there was no apparent difference following neutron-beam irradiation. High-LET radiation can overcome the radioresistance of GSLCs by producing unrepairable DNA DSBs. High-LET radiation therapy might have the potential to overcome GBM''s resistance to X-rays in a clinical setting.     

Nardilysin prevents amyloid plaque formation by enhancing α-secretase activity in an Alzheimer's disease mouse model

Amyloid beta (Aβ) peptide, the main component of senile plaques in patients with Alzheimer's disease (AD), is derived from proteolytic cleavage of amyloid precursor protein (APP) by β- and γ-secretases. Alpha-cleavage of APP by α-secretase has a potential to preclude the generation of Aβ because it occurs within the Aβ domain. We previously reported that a metalloendopeptidase, nardilysin (N-arginine dibasic convertase; NRDc) enhances α-cleavage of APP, which results in the decreased generation of Aβ in vitro. To clarify the in vivo role of NRDc in AD, we intercrossed transgenic mice expressing NRDc in the forebrain with an AD mouse model. Here we demonstrate that the neuron-specific overexpression of NRDc prevents Aβ deposition in the AD mouse model. The activity of α-secretase in the mouse brain was enhanced by the overexpression of NRDc, and was reduced by the deletion of NRDc. However, reactive gliosis adjacent to the Aβ plaques, one of the pathological features of AD, was not affected by the overexpression of NRDc. Taken together, our results indicate that NRDc controls Aβ formation through the regulation of α-secretase.     

Vesicular nucleotide transporter-immunoreactive type I cells associated with P2X3-immunoreactive nerve endings in the rat carotid body

ATP is the major excitatory transmitter from chemoreceptor type I cells to sensory nerve endings in the carotid body, and has been suggested to be released by exocytosis from these cells. We investigated the mRNA expression and immunohistochemical localization of vesicular nucleotide transporter (VNUT) in the rat carotid body. RT-PCR detected mRNA expression of VNUT in extracts of the tissue. Immunoreactivity for VNUT was localized in a part of type I cells immunoreactive for synaptophysin (SYN), but not in glial-like type II cells immunoreactive for S100 and S100B. Among SYN-immunoreactive type I cells, VNUT immunoreactivity was selectively localized in the sub-population of tyrosine hydroxylase (TH)-immunorective type I cells associated with nerve endings immunoreactive for the P2X3 purinoceptor; however, it was not detected in the sub-population of type I cells immunoreactive for dopamine beta-hydroxylase. Multi-immunolabeling for VNUT, P2X3, and Bassoon revealed that Bassoon-immunoreactive products were localized in type I cells with VNUT immunoreactivity, and accumulated on the contact side of P2X3-immunoreactive nerve endings. These results revealed the selective localization of VNUT in the subpopulation of TH-immunoreactive type I cells attached to sensory nerve endings and suggested that these cells release ATP by exocytosis for chemosensory transmission in the carotid body.     

Sevoflurane anaesthesia causes a transient decrease in aquaporin-2 and impairment of urine concentration

Sevoflurane anaesthesia is occasionally associated with polyuria, but the exact mechanism of this phenomenon has not been clarified. Aquaporin-2 (AQP2) is an arginine vasopressin (AVP)-regulated water channel protein localized to the apical region of renal collecting duct cells and is involved in the regulation of water permeability. To elucidate the effect of sevoflurane anaesthesia on urine concentration and AQP2, we have compared serum and urinary concentrations of AVP, AQP2 and osmolar changes during sevoflurane and propofol anaesthesia. General anaesthesia was induced with sevoflurane or propofol in 30 patients for a variety of major surgical procedures. Blood and urine samples were obtained from patients at baseline, and 90 and 180 min after induction of anaesthesia. AVP and AQP2 concentrations were measured by radioimmunoassay. In both groups, plasma and urinary concentrations of AVP increased similarly during anaesthesia although plasma osmolality remained unchanged. Although urinary AQP2 excretion in the propofol group increased together with changes in plasma and urinary AVP, urinary AQP2 was significantly lower at 90 min in the sevoflurane group. Urine osmolality in the sevoflurane group also showed a transient but significant decrease in parallel with suppression of AQP2. Our data suggest that sevoflurane anaesthesia transiently produced an impaired AQP2 response to an increase in intrinsic AVP.      

Correlation Between Vascular Endothelial Growth Factor C Expression and Lymph Node Metastasis in T1 Carcinoma of the Colon and Rectum

Purpose. Vascular endothelial growth factor C (VEGF-C) is known to be associated with the development of the lymphatic vessel system. Recently, VEGF-C is thought to be correlated with lymph node metastasis in some malignant tumors. In this study, we investigated the correlation between VEGF-C expression and lymph node metastasis in early carcinoma of the colon and rectum. Methods. Two hundred and twenty-one endoscopically biopsied specimens from patients with T1 colorectal carcinoma prior to operation were investigated by an immunohistochemical study. Results. VEGF-C expression was more frequently observed in the tumors with nodal metastasis than in those without metastasis. Moreover, a multivariate analysis indicated that VEGF-C expression is an independent predictor of lymph node metastasis. Conclusion. VEGF-C staining using endoscopically biopsied specimens prior to operation could be of use in the prediction of lymph node metastasis and in preoperative selection of treatment in patients with T1 colorectal carcinoma.     

Laparoscopic resection of ileal lipoma diagnosed by multidetector-row computed tomography

Intussusception is rare in adults and it is difficult to diagnose on admission. We present the case of a 43-year-old woman with the chief complaint of nausea and upper abdominal pain. Abdominal multidetector-row computed tomography showed ileo-ileal small bowel intussusception with an intraluminal soft tissue mass with attenuation numbers suggestive of a lipoma. The patient was treated with a laparoscopic-assisted extracorporeal partial resection of the small bowel including ileal lipoma, followed by a functional end-to-end anastomosis. Histologic diagnosis of the resected tumor, 2.4×2.0×2.0 cm, was an intestinal lipoma. This case serves as the basis of a review of small bowel intussusception in adults secondary to lipomas. It focuses on the utility of multidetector-row computed tomography and the cosmetic, physical, and economic benefits of laparoscopic surgery as well as the rarity of the disease.     

Recombinant cell-detecting RaDR-GFP in mice reveals an association between genomic instability and radiation-induced-thymic lymphoma

In this study, we aimed to investigate how homologous recombinant (HR)-related genomic instability is involved in ionizing radiation (IR)-induced thymic lymphoma in mice. We divided five-week-old Rosa26 Direct Repeat-GFP (RaDR-GFP) transgenic mice into non-IR control and IR groups and exposed the mice in the IR group to a 7.2 Gy dose of γ-rays, delivered in 1.8 Gy fractions, once a week for four weeks. We then estimated mouse survival and recorded their body, thymus, and spleen weights. The frequency of HR events in the chromosomes of the thymus, bone marrow, and spleen cells and the phenotype of thymic lymphoma cells were analyzed using fluorescence-activated cell sorting (FACS). We found that most mice in the IR group developed thymic lymphoma, their survival rate decreasing to 20% after 180 days of IR exposure, whereas no mice died in the non-IR control group until day 400. The thymus and spleen weighed significantly more in the IR-4-month group than that in the non-IR group; however, we observed no significant differences between the body weights of the control and IR mice. FACS analysis indicated that the frequency of HR events significantly increased at two and four months after the last IR dose in the bone marrow and thymus cells, but not in the spleen cells of RaDR-GFP transgenic mice, suggesting that recombinant cells accumulated in the thymus upon IR exposure. This suggests that IR induces genome instability, revealed as increased HR, that drives the development of thymic lymphoma. Additionally, phenotypic analysis of lymphoma cells showed an increase in the CD4^-/CD8⁺ (CD8SP) cell population and a decrease in the CD4⁺/CD8^- (CD4SP) cell population in the IR-4-month group compared to that in the non-IR group, indicating that IR induces an aberrant cell phenotype characteristic of lymphoma. In conclusion, we observed a significant increase in HR events and abnormal phenotype in thymic lymphoma cells at two and four months after IR exposure in both the thymus and bone marrow tissues, suggesting that genomic instability is involved in the early stages of thymic lymphomagenesis. Our study indicates that HR-visualizing RaDR-GFP transgenic mice can help explore the links between the molecular mechanisms of genome instability and IR-induced tumorigenesis.     

Cytological features of carcinoma of the collecting ducts of Bellini in voided urine cytology

Carcinoma of the collecting ducts of Bellini (CCDB) is a rare histological type of renal cell carcinoma. This article describes the cytological features of CCDB in voided urine, confirmed on the basis of the histopathology and immunohistochemistry. The CCDB cells occurred singly in loose aggregates and in small clusters, occasionally in a rosette‐like structure. There were various types of cancer cells, including round to oval, spindle, and tadpole‐like cells. The nuclei usually showed coarse chromatin, inconspicuous nucleoli, and lacy to vacuolated cytoplasm. CCDB of the kidney is a rare cytodiagnostic challenge in voided urine cytology alone. When the cytological diagnosis is considered, it is necessary to perform immunocytochemistry and correlate the clinical history and imaging studies. Diagn. Cytopathol. 2009. © 2009 Wiley‐Liss, Inc.