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Medical Sciences50%

Selected Abstracts

Summer changes in cyanobacterial bloom composition and microcystin concentration in eutrophic Czech reservoirs

ENVIRONMENTAL TOXICOLOGY, Issue 3 2006
Petr Znachor
Abstract In mid-July and August 2003 and 2004, 18 reservoirs in the Czech Republic were sampled for phytoplankton species composition and concentration of intracellular microcystins (MCs). As a consequence of high nutrient loading, most of the reservoirs experienced cyanobacterial blooms of various intensities, with the prevalence of cyanobacteria increasing markedly in August, along with a conspicuous shift in species composition toward dominance of Microcystis spp. Microcystins were detected in 90% of the samples, and their amount also increased considerably in August, reflecting the cyanobacterial biomass. In Microcystis -dominated samples, a significantly higher amount of MCs (p < 0.001) occurred than in samples in which other taxa prevailed. Microcystins were positively correlated with chlorophyll a and cyanobacterial biovolume (p < 0.05, R2 = 0.61 and 0.66, respectively), with the strongest correlation found for Microcystis spp. biovolume (p < 0.001, R2 = 0.87). This taxon was the most important producer of MCs in Czech reservoirs. The main structural variants of MCs were MC-LR, MC-RR, and MC-YR. This study's data also indicate that the relative share of MC variants (MC-LR and MC-RR) varies considerably with time, most likely as a consequence of different species and strain compositions during the summer. This study clearly demonstrates a high prevalence of MC-producing cyanobacteria in Czech reservoirs. Therefore, regular monitoring of these reservoirs is highly desirable in an effort to minimize potential health risks to the human population. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 236,243, 2006. [source]

Osteopontin expression correlates with prognostic variables and survival in clear cell renal cell carcinoma

JOURNAL OF SURGICAL ONCOLOGY, Issue 4 2006
Koviljka Matusan MD
Abstract Background and Objectives Osteopontin (OPN) is a phosphorylated glycoprotein with diverse functions including tumorigenesis and tumor cell metastasis. Recently, it has been detected in a growing number of human tumors, and assessed as a potential prognostic marker. The aim of this study was to analyze the expression of OPN in normal renal tissue and clear cell renal cell carcinomas (CRCCs), and to assess its prognostic significance. Methods The expression of OPN protein was immunohistochemically analyzed in 171 CRCCs and compared to usual clinicopathological parameters such as tumor size, nuclear grade, pathological stage, Ki-67 proliferation index, and cancer-specific survival. Results In normal renal parenchyma, the expression of OPN was seen in distal tubular epithelial cells, calcifications, and some stromal cells. The upregulation of OPN was observed in 61 CRCCs (35.7%) in the form of cytoplasmic granular staining of various intensities. Statistical analysis showed correlation of the OPN expression with tumor size (P,<,0.001), Fuhrman nuclear grade (P,<,0.001), pathological stage (P,=,0.011), and Ki-67 proliferation index (P,<,0.001). Moreover, patients with OPN-positive tumors had significantly worse prognosis in comparison to patients with tumors lacking OPN protein (P,=,0.004). Conclusion Our results suggest that overexpression of OPN is involved in the progression of CRCC. J. Surg. Oncol. 2006;94:325,331. © 2006 Wiley-Liss, Inc. [source]

Increased expression of cyclooxygenase-2 in human salivary gland tumors

PATHOLOGY INTERNATIONAL, Issue 10 2001
Kazunari Sakurai
We examined the immunohistochemical localization of cyclooxygenase (COX)-2 in human salivary gland tumors. Thirty salivary gland adenomas (SGA), 40 salivary gland carcinomas (SGC) and 15 normal salivary glands (NSG) were studied. NSG showed restricted COX-2 staining only in the epithelial cells of salivary ducts. In contrast, COX-2 protein was detected in 27 cases of SGA (90%), except for three myoepitheliomas, and in all cases of SGC (100%) at various intensities and in various fashions. Thirteen SGA (43%) and 36 SGC (90%) cases showed strong COX-2 staining predominantly in tumor cells containing ductal components, as did serous and mucous acinic components of acinic cell carcinomas, mucoepidermoid carcinomas and mucinous carcinomas. These findings may suggest that COX-2 in salivary gland tumors is expressed in tumor cells derived from pluripotential ductal epithelium that can histologically develop into either serous or mucinous acinar cells. [source]

Light propagation in a coupled waveguide-triple quantum well structure

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2008
M. Yamaguchi
Abstract The light propagation in a waveguide which was weakly coupled to a quantum well (QW) structure was studied to demonstrate the detectability of the electronic states in the small area of QW. The small area of QW was made with a GaAs/AlGaAs asymmetric triple QW. Since the electronic states in the triple QW were easily controlled by an electric field which was induced by an optical injection, we observed the optical spectra obtained from the waveguide under the various intensities of optical injection. The spectral change was observed around the characteristic wavelengths of the QW. In order to verify the observed spectral change, we measured the optical spectra of the traveling wave in a sample whose QW surface has been etched off. By comparing the results, we interpreted that the spectral change is due to the reconstruction of the electronic states in the small area of QW due to the optically excited carriers. This proves the detection of small electronic state changes in the small area of QW with the traveling light in the waveguide. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]