Temporal variabilities of the concentrations of intra- and extracellular microcystin and toxic Microcystis species in a hypertrophic lake,Lake Suwa,Japan (1991–1994)

Temporal variability in the concentration of toxic heptapeptide microcystin was studied during the warm season of four years (1991–1994) in a hypertrophic lake (Lake Suwa) in central Honshu, Japan. Lake water samples (ca. 5 L) were filtered to separate intracellular microcystin (cell fraction) from extracellular microcystin (filtered lake water fraction). These fractions were analyzed to measure the total quantity of microcystin in lake water. Total amounts of extra- and intracellular microcystin were measured with high performance liquid chromatography. Concentrations of intracellular microcystin usually exceeded concentrations of extracellular microcystin (24 out of 26 times). High concentrations of intracellular microcystin were found during the exponential growth phase of the blooms, whereas concentrations of extracellular microcystin were highest at the end of the blooms. However, concentrations of extracellular microcystin remained very small (<4μg/L) compared to the levels of intracellular microcystin. The relatively higher percentages of microcystin in filtered lake water ( > 20%) at the end of blooms suggests that release of microcystin from cells occurs during senescence and the decomposition period of Microcystis cells. © 1998 John Wiley & Sons, Inc. Environ Toxicol Water Qual 13 : 61–72, 1998     

Cleavage of hepatocyte growth factor activator inhibitor-1 by membrane-type MMP-1 activates matriptase

Co-expression of membrane-type 1 (MT1)-MMP with hepatocyte growth factor activator inhibitor-1 (HAI-1) in HEK293T cells resulted in cleavage of HAI-1 to produce three fragments. Recombinant MT1-MMP was shown to cleave HAI-1 protein in vitro. Hepatocyte growth factor activator inhibitor-1 was initially identified as the cognate inhibitor of matriptase, a transmembrane serine protease that processes urokinase-type plasminogen activator (uPA). Co-expression of HAI-1 with matriptase suppressed matriptase protease activity, and co-expression of MT1-MMP with them resulted in recovery of matriptase activity by stimulating shedding of HAI-1 fragments. Matriptase protein was detected in squamous carcinoma-derived HSC-4 cells, however, matriptase protease activity was undetectable. Transfection of siRNA for HAI-1 enhanced serine protease activity, which was suppressed by cotransfection of matriptase siRNA. Collagen-gel culture or treatment with concanavalin A (ConA) of HSC-4 cells enhanced MT1-MMP activity, which induced shedding of HAI-1 fragments and conversely stimulated uPA activation by these cells. Serine protease activity, including uPA activation of cells treated with ConA, was abrogated by downregulation of either matriptase or MT1-MMP through the transfection of each siRNA. These results suggest that MT1-MMP induced by collagen-gel culture or ConA treatment causes cleavage and shedding of HAI-1 protein, which allows activation of matriptase in HSC-4 cells. HSC-4 cells showed a characteristic invasive growth by forming vacuole-like structures in collagen gel, which was suppressed by transfection of siRNA for either MT1-MMP or matriptase, suggesting that activation of matriptase through the cleavage of HAI-1 is one of the MT1-MMP multifunctions essential for invasive growth of HSC-4 cells.     

Hepatotoxic microcystins and neurotoxic anatoxin-a in cyanobacterial blooms from Korean lakes

Cyanobacterial bloom samples were collected in the warm season during 1992–1995 from the 12 lakes in Korea. Six species each of Microcystis and Anabaena, and two of Oscillatoria were identified in these lakes. The cyanotoxins of 47 samples collected from the lakes were identified as microcystins-RR, -YR, -LR; desmethyl-7-microcystin-LR (7-DMLR), plus anatoxin-a. Microcystins were the main components of these cyanotoxins, while anatoxin-a was detected in samples from a few lakes. Thirty-four of the 47 samples, included microcystins and the total amounts of microcystin ranged between 20–1500 μg/g freeze-dried bloom material. In four of the 26 samples, the samples contained anatoxin-a, though the amounts varied. The total microcystin concentration in 30 samples from the lakes was equal to the cellular microcystin in these lakes because no extracellular microcystin was detected. All the lakes except for Lakes Younglang and Mijae are a source of drinking water, so the presence of cyanotoxin can be a potential threat and requires more attention to water treatment. © 1998 John Wiley & Sons, Inc. Environ Toxicol Water Qual 13: 225–234, 1998     

Histometric analysis of the distal pancreas in pancreatic head cancer

To clarify the histological status of the pancreas tail after pancreatoduodenectomy (PD), fibrosis, islets of Langerhans, and A, B, and D cells were examined histometrically in surgical cases of pancreatic cancer. The same investigations were also performed during an autopsy examination of the pancreas tail of survivors of surgery who had received either PD or total pancreatectomy with segmental autotransplantation (SAT). In the surgical cases, fibrosis and the islet percentage compared with nonpancreatic cancer cases were significantly higher while the B cell ratio was significantly lower. In addition, in pancreatic cancer patients, the fibrosis and islet ratio in the group with a blocked pancreatic duct were higher while the B cell ratio was lower than in the group with an open pancreatic duct. A direct relationship between the islet ratio and the degree of fibrosis, and an inverse relationship between the B cell ratio and the degree of fibrosis, were thus found. From the autopsy cases, the fibrosis progressed and the islet ratio increased following PD, but after SAT only the islet ratio increased compared to the time of surgery. The progression of fibrosis after PD thus suggests the presence of some problems in both the surgical method and postoperative management.     

Diagnostic value of integrin alpha3, beta4, and beta5 gene expression levels for the clinical outcome of tongue squamous cell carcinoma

BACKGROUND: The objective of the current study was to identify biomarkers that reflect the clinical course of squamous cell carcinoma of the tongue (TSCC). METHODS: TSCC tissue samples from 66 patients were subjected to gene expression analysis by real-time polymerase chain reaction. Eleven integrin family genes and 14 genes used for normalization, including housekeeping genes and genes that encode desmosomal, cytoskeletal, and extracellular matrix molecules, were considered. Multivariate statistical analysis was performed on 154 expression ratios of integrin genes with clinical parameters. RESULTS: In principal-component analysis, the first principal component was related to the outcome of death, and the second principal component mainly reflected the tendency for cervical lymph node (LN) metastasis. The former axis consisted of the variance of the integrin beta4 gene (ITGB4) and ITGB5 expression levels, and the latter axis agreed with the expression level of the integrin alpha3 gene (ITGA3). Multivariate logistic regression analysis with cervical LN metastasis as the response variable concordantly identified ITGA3/junction plakoglobin gene (JUP) expression (P=.02) and ITGB5/paxillin gene (PXN) expression (P=.04) as significant factors. Only ITGB4/JUP expression was identified as a significant factor in terms of the outcome of death (P<.00049) by a Cox proportional hazards model. The group with high ITGB4/JUP levels exhibited a significantly high death rate on a Kaplan-Meier curve (P<.0001; Wilcoxon and log-rank tests). CONCLUSIONS: The expression levels of ITGA3, ITGB4, and ITGB5 with functional normalization by desmosomal or cytoskeletal molecule genes were selected as candidate biomarkers for cervical LN metastasis or for the outcome of death in TSCC.     

EGD1 (β-NAC) mRNA is localized in a novel cytoplasmic structure in Saccharomyces cerevisiae

RNA localization is a common mechanism for recruiting proteins to specific regions of a cell, which causes cell polarization and sometimes asymmetric division. We found that EGD1 mRNA accumulates dose-dependently as a cytoplasmic granule in Saccharomyces cerevisiae. EGD1 encodes a β-subunit of the nascent polypeptide-associated complex (NAC). NAC is a heterodimer consisting of α- and β-subunits, associated with ribosomes and thought to be involved in the folding of nascent polypeptide chains. Analysis of deletion constructs showed that the localization of EGD1 mRNA requires both an upstream region and an ORF of EGD1, suggesting that the translation of Egd1p is important for localization. We also showed that Egd1p and P-body components are co-localized with EGD1 mRNA. This granule, named the EGD1 granule, has features similar to cellular inclusions containing aggregated proteins. Disruption of microtubules by treatment with a drug, benomyl, resulted in loss of the EGD1 granule. When the expression level of EGD2 encoding the αNAC increased, the percentage of cells showing the EGD1 granule decreased, suggesting that the granular distribution of EGD1 depends on the quantitative balance between α- and β-subunits of NAC. Taken together, we propose a novel microtubule-dependent mechanism for controlling NAC through RNA localization.     

Case report of transarterial chemoembolization to lymph node metastasis of hepatocellular carcinoma

We performed transarterial chemoembolization (TACE) on the 67-year-old man who had hepatectomy for hepatocellular carcinoma with hepatitis C, recurrence in the liver and lymph nodes.The metastasis in lymph node did not show a clear increase until dying, and TACE showed the possibility of one treatment method to the metastasis in lymph node of the hepatocellular carcinoma.     

Component-dependent urine responses in the rat accessory olfactory bulb

To investigate how pheromonal information is processed in the rat accessory olfactory bulb, we optically imaged intrinsic signals to obtain high-resolution maps of activation induced by urinary stimulation. Application of volatile components in male urine mainly induced activation in the anterior accessory olfactory bulb, irrespective of the sex, whereas volatile female urine elicited activation not only in the anterior but also to some extent in the caudal part of the posterior accessory olfactory bulb of male, but not female, rats. Nonvolatile components of both male and female urine induced activation mainly in the rostral part of the posterior and to a lesser extent in the anterior accessory olfactory bulb, irrespective of the sex. These results indicate that volatile and nonvolatile urinary components activate the anterior and posterior subdivisions of the accessory olfactory bulb, respectively.