bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental Conditions of Percid Waters in Central Europe
Authors: Entz B.
Published: April 2011

A brief review of the limnology of central European waters indicated that, except for calcium in the bottom sediments, mesotrophic lakes were intermediate in nutrient concentrations between oligotrophic and eutrophic waters. Other biotic characteristics also attained maxima in mesotrophic lakes. For example, the existence of distinctive phytoplankton, invertebrate, and fish communities, implied certain qualitative properties of mesotrophic waters rather than only quantitative intermediacy on the oligotrophic–eutrophic cline. These properties, in part, represent some aspects of percid habitat that differ from those of other fish communities. Key words: Percidae, algae, bottom sediments, cultural effects, eutrophication, limnology, mesotrophy, trophic levels, primary production
Factors in the Declining Contributions of Walleye (Stizostedion vitreum vitreum) to the Fishery of Lake Nipissing, Ontario, 1960–76
Authors: Anthony D. D. , Jorgensen C. R.
Published: April 2011

Analysis of the 1960–76 creel survey data for Lake Nipissing and relevant data collected by the Lake Nipissing Fisheries Assessment Unit from 1969 to 1976 showed a generally declining walleye (Stizostedion vitreum vitreum) contribution to the Lake Nipissing fishery. Variable year-class strengths alone did not adequately account for the changes. Overexploitation of the resource was strongly suggested by decreased catches per unit of effort, recruitment of younger walleye (many of which probably never spawned) into the fishery at least after 1968, and increased growth rate. The population is probably affected as well by climatic factors, interactions with white suckers (Catostomus commersoni), northern pike (Esox lucius), and yellow perch (Perca flavescens), and by technology and watershed influences. Key words: walleye, Lake Nipissing Ontario, Lake Nipissing fishery, Percidae, Stizostedion
Population Dynamics of Walleye (Stizostedion vitreum vitreum) and Yellow Perch (Perca flavescens) in Lake St. Clair, Especially During 1970–76
Authors: Johnston D. A.
Published: April 2011

The fish community in Lake St. Clair has remained fairly stable over the past century despite extensive shoreline modifications, a tenfold increase in population in the drainage area, and exploitation from commercial and recreational fisheries. The lake is productive because of its shallowness and fertile drainage basin. The flushing action of clean water from Lake Huron has restrained deterioration of habitat from euthrophication in most areas.Annual commercial fishery landings of walleye (Stizostedion vitreum vitreum) in the 1960s were five times greater than in the previous 50 yr. The larger catches were due, in part, to increased effort, but also reflect a real increase in the walleye population. In contrast, the sauger (S. canadense) declined in abundance through the 1950s and disappeared from commercial landings in the early 1960s. As commercial fishing in Ontario waters of Lake St. Clair was banned in 1970 due to the discovery of high concentrations of mercury in fishes, information on the percid populations was restricted to that obtained from index fishing. Between 1970 and 1976, in association with weak year-classes, the mean age of walleye increased from 2.9 to 5.8 yr. Direct correlations between year-class strength and environmental factors were not evident from the available data. Fishing pressure was reduced considerably after 1970 and is not considered to be an important factor in the low recruitment. The yellow perch (Perca flavescens) population showed no evidence of a change in age distribution during the 1970–76 period. The reasons for the reduction in walleye recruitment after 1970 are not clear, but it is possible that the succession of strong year-classes in the 1960s was exceptional and that the recruitment in the 1970s is closer to the normal condition for walleyes in Lake St. Clair. Key words: Percidae, Lake St. Clair percids, Stizostedion, Perca, population dynamics, exploitation, community ecology
Factors Influencing Year-Class Strength of Percids: A Summary and a Model of Temperature Effects
Authors: Koonce J. F. , Bagenal T. B. , Carline R. F. , Hokanson K. E. F. , Nagięć M.
Published: April 2011

Factors regulating year-class strength in the percid genera Stizostedion and Perca are summarized. Some index of water temperature regime correlates significantly with year-class strength of percids in many water bodies. Moderate synchrony of year-class strength is noted for walleye (Stizostedion vitreum vitreum) in several lakes in North America. A probablistic model is proposed to explain the basis of temperature dependence of year-class strength in percids, but tests of the model using Lake Erie data indicated that observed correlations between temperature and year-class strength of yellow perch (Perca flavescens) and walleye may not be the result of direct effects of the temperature regime on survivorship of early life-history phases. Key words: Percidae, year-class strength, temperature, probalistic model, early life history
Blood Chemistry, Biochemical Composition, and the Annual Reproductive Cycle in the Giant Scallop, Placopecten magellanicus, from Southeast Newfoundland
Authors: Thompson R. J.
Published: April 2011

Gametogenesis in the giant scallop, Placopecten magellanicus (Gmelin), occurs in early summer and spawning takes place during August and September. The gonad differentiates between March and May, when the water temperature is low (0 to −1 °C) and food supply high. Gonad growth also begins at this time. Energy reserves from the previous year do not seem to play a significant part in subsequent growth and maturation of the gonad. There is no accumulation of metabolic reserves in the scallop gonad after spawning; in winter, the gonad is very small and inactive. Levels of lipid (mostly phospholipids and free sterols), protein, low molecular weight carbohydrate, and glycogen increase in the plasma during the period of gonad growth and maturation. The amount of glycogen in the circulating hemocytes is greater in summer than in winter. Key words: Placopecten magellanicus, bivalve, scallop, reproductive cycle, blood, hemolymph, hemocyte, blood chemistry, glycogen, phospholipid, sterol
Some Aspects of Benthic Production in a Salmonid Rearing Channel
Authors: Williams D. Dudley , Mundie J. H. , Mounce D. E.
Published: April 2011

Experiments on optimizing the use of benthos in a salmonid rearing channel are described. The cropping potential of invertebrates for use as fish food was measured by substrate recolonization which showed that 80,000 animals, weighing approximately 0.62 g (dry weight), could be liberated from 1 m2 of clean gravel substrate to a depth of 15 cm every 15 days. Recolonization curves expressed in terms of number of taxa, total numbers, and biomass gave the following patterns: asymptotic regression curve, logistic growth curve, and a straight line, respectively. Individual curves of the major taxa showed a variety of patterns. Small accumulations of fish production wastes (up to 9 ℓ/m2 of food pellets and up to 4.5 ℓ/m2 offish feces) increased benthic standing crop by as much as 3 times, but larger accumulations resulted in a decline together with a decrease in benthos diversity. We suggest that invertebrates ameliorate these potential pollutants through their feeding and living habits. Key words: benthic production, salmon rearing, benthos recolonization, fish wastes
Influence of Ice Cover and Man on the Odd-Chain Hydrocarbons and Fatty Acids in the Waters of Jeddore Harbour, Nova Scotia
Authors: Paradis M. , Ackman R. G.
Published: April 2011

Water samples from Jeddore Harbour, Nova Scotia, that passed through a 400-μm screen were examined at monthly intervals between November 1970 and December 1971. They were found to contain 16–390 μg extractable lipid/ℓ water. The fatty acid content of the lipids was characterized by low levels of unsaturation and a predominance of components of moderate chain length (C14–C18). The content of n-alkanes recovered from the water samples varied normally from 1 to 10 μg/ℓ water and could not be given a specific origin, although certain details pointed to local pollution as the primary origin. In particular, pristane and phytane virtually disappeared during the period of winter ice-cover when local boat operations ceased. Neither hydrocarbon nor fatty acid details could be conclusively related to unusually high levels of odd-chain fatty acids found in Jeddore Harbour rainbow smelt, Osmerus mordax. The impact of hurricane Beth was unexpectedly low, implying that the unusual freshwater runoff did not mix with the normal salt water or disturb the basically marine character of Jeddore Harbour. Key words: Jeddore Harbour, odd-chain hydrocarbons, odd-chain fatty acids, dissolved hydrocarbons, pristane, phytane, ice cover, hurricane runoff
Avoidance of Low pH in Selection of Spawning Sites by Brook Trout (Salvelinus fontinalis)
Authors: Johnson David W. , Webster Dwight A.
Published: April 2011

Brook trout (Salvelinus fontinalis) show a strong preference for upwelling water in selection of precise spawning sites. Advantage was taken of this behavior in observing discrimination of pH by 48 breeding females. When artificial aquifers delivered ambient (6.7), alkaline (8.0), and acid water (varied at pH 4.0, 4.5 and 5.0 in three trials), females clearly avoided upwellings of pH 4.0 and 4.5 in preference to alkaline and ambient upwelling. Discrimination was not evident at pH 5.0. As natural springs in the Adirondack area are likely to be alkaline, the strong preferences of brook trout for alkaline upwelling water for breeding sites assures a satisfactory environment through egg and larval stages for at least this environmental condition. Key Words: behavior, acidity, brook trout, spawning
Vertical and Seasonal Distribution of Chlorophyll a in Lake Michigan
Authors: Brooks Arthur S. , Torke Byron G.
Published: April 2011

Vertical and seasonal distribution of chlorophyll a was observed for 2 yr at an offshore station in Lake Michigan. Chlorophyll a concentrations increased uniformly at all depths during spring reaching 3–4 mg/m3 by late May. Thermal stratification was followed by development of a subthermocline chlorophyll peak between 10 and 30 m that reached 8.5 mg/m3 by late July. The major subthermocline peak collapsed in mid-August but was followed by two lesser peaks at depths of 10 and 30 m. Autumn mixing dispersed these peaks in the mixed layer, increasing the chlorophyll content of the epilimnion at a time when integral chlorophyll levels were declining. At fall overturn chlorophyll concentrations were uniformly distributed at approximately 1 mg/m3, where they remained throughout the winter. The presence of a deep chlorophyll maximum in Lake Michigan adds a new dimension to limnological studies of the Great Lakes. The influence of this peak must be considered in future investigations of food chain dynamics and eutrophication processes in the Great Lakes system. Key words: Laurentian Great Lakes, limnology, chlorophyll a, spatial distribution, phytoplankton dynamics
Temperature and Water Velocity Effects on the Swimming Performances of Young-of-the-Year Striped Mullet (Mugil cephalus), Spot (Leiostomus xanthurus), and Pinfish (Lagodon rhomboides)
Authors: Rulifson Roger A.
Published: April 2011

Swimming performances of young-of-the-year striped mullet (Mugil cephalus), spot (Leiostomus xanthurus), and pinfish (Lagodon rhomboides) were tested by examining the combination of physical endurance and swimming behavior to provide information on potential fish entrainment and impingement problems at industrial intakes. Tests were conducted at three temperatures (15–25 °C) and six water velocities (12–48 cm/s). Fish lengths ranged from 1.4 to 7.0 cm TL. Fish tested at higher temperatures exhibited increased time for steady swimming and for impingement avoidance. Temperature was also positively correlated with maximum swimming speeds and with the number of bursts performed during drift–burst activity (drifting with the current and returning upstream with a burst of swimming). Increased water velocities resulted in decreased times of steady swimming and impingement avoidance, and reduced drift–burst activity. Larger fish avoided impingement longer and had faster maximum swimming speeds; however, smaller fish showed stronger rheotaxis and swam steadily for longer periods at equal water velocities. Abnormally heavy mullet and spot had reduced capabilities for position maintenance (steady swimming) which may decrease their ability to avoid impingement. Key words: swimming speeds, temperature, water current, impingement, behavior, mullet, spot, pinfish
Healing of Wounds and Location of Tags in Atlantic Herring (Clupea harengus harengus) Released with Abdominally Inserted Magnetic Tags
Authors: Winters G. H.
Published: April 2011

Information derived from Atlantic herring (Clupea harengus harengus) released with abdominally inserted magnetic tags and recovered by an electronic tag-detection system indicated that sustained mortality due to internal damage caused by the tag or the incision wound was probably minimal. In addition, tags that have not become attached to the body wall and internal organs prior to spawning will to a large degree be extruded with the gonadal products during spawning. Key words: tagging, wounding, mortality
Clinal Variation in Scale Characters of Atlantic Salmon (Salmo salar) Based on Discriminant Function Analysis
Authors: Lear W. H. , Misra R. K.
Published: April 2011

Scales of adult Atlantic salmon (Salmo salar) were collected from 18 river systems in eastern North America from 55°33′N in Labrador to 44°33′N in Maine and to 44°23′N in Nova Scotia during 1968, 1973–75. Analysis of four scale characters, namely circuli in first annual river zone, circuli in second annual river zone, smolt age, and circuli in first annual marine zone, demonstrated that significant differences occurred in each of these characters between river systems and latitude. The numbers of circuli in each of the three growth zones increased from north to south, while the smolt ages decreased from north to south. A discriminant function applied to these four characters employing latitude as a "dummy" variable indicated that the discriminant function contributed significantly to the clinal trend and 73.7% of the total variation was explained by this discriminant function. Key words: adult Atlantic salmon; scale characters; salmon; latitudinal cline, scale characters; clinal discriminant function
Reproductive Isolation Between Pumpkinseed (Lepomis gibbosus) and Longear Sunfish (L. megalotis) (Centrarchidae) in the Thames River, Southwestern Ontario
Authors: Keenleyside Miles H. A.
Published: April 2011

In the middle branch of the Thames River, southwestern Ontario, nest construction and occupation by male pumpkinseeds (Lepomis gibbosus) began earlier and reached a peak earlier in the season than nesting by male longear sunfish (L. megalotis). Nevertheless the two species' breeding seasons broadly overlapped. All pumpkinseed nests occurred in backwater areas, where water flow is minimal, the substrate is a deep layer of detritus and mud, and aquatic plant growth is heavy. Some longear nests were in the backwaters, but most were in the main river, where water flow is variable, the substrate mainly sand and gravel, and vegetation sparse. Females of both species are nonterritorial and were found throughout the study area. Hybrid sunfish are present in the area and opportunities for interspecific breeding would seem to be greatest in backwaters, where males of both species may occupy nests close to each other. However, the only observed interbreeding was between female pumpkinseeds and male longears in the main river. Behavioral barriers to interbreeding occasionally break down under the turbulent social conditions associated with breeding in large longear colonies. Key words: sunfish, reproductive isolation, longear, pumpkinseed, habitat, season, behavior
No Safe Place.
Authors: Hamilton A. L.
Published: April 2011

not available
Comparative Recoveries of Planted Yearling and Fall-Fingerling Brook Trout (Salvelinus fontinalis) from Ontario Lakes
Authors: Fraser J. M.
Published: April 2011

Yearling and fall-fingerling brook trout (Salvelinus fontinalis) were planted in two lakes with few or no resident fish species and in three lakes with resident populations. The comparative recoveries of the two size-groups of trout planted were assessed by creel census and/or intensive gillnetting. Recoveries of planted yearling brook trout were greater from lakes supporting few or no resident fish species (15.9–35.9%) and less in lakes supporting suckers, minnows, and sticklebacks (5.9–14.8%). Experience was similar with fall fingerlings planted in the same set of lakes though comparative recoveries were less. Lakes with few fish competitors yielded 3.5–4.8 kg of trout for each kilogram of fall fingerlings planted compared with 2.9–3.0 kg for each kilogram of yearlings planted. The returns of trout from lakes also supporting resident species were only 0.3–0.8 kg for each kilogram of yearlings or fall fingerlings planted. Key words: Salvelinus fontinalis, planting, survival, growth, yield
A Simple Model For Cross-Shelf Mixing on the Scotian Shelf
Authors: Houghton Robert W. , Smith Peter C. , Fournier Robert O.
Published: April 2011

The longshore gradients of temperature, salinity, and nitrate concentration along the Scotian Shelf, and their fluxes at a fixed mooring south of Halifax, have been measured separately. Water-mass analysis indicates that the water at the eastern end of the shelf is diluted with slope water by 40% at Halifax as a result of cross-shelf mixing. Recent estimates of the annual mean transport along the shelf are used to infer the longshore gradients supported by the shelf-break fluxes in the context of a simple box model. The observed longshore gradients of temperature, salinity, and nitrate concentration are consistent with productivity requirements and measured low-frequency eddy fluxes at the edge of the Scotian Shelf. Key words: low-frequency eddy fluxes, nutrient enrichment, longshore gradients, cross-shelf mixing, Scotian Shelf
Comparison of Oiled and Unoiled Intertidal Communities in Chedabucto Bay, Nova Scotia
Authors: Thomas Martin L. H.
Published: April 2011

During 1976, detailed surveys of four oiled and four unoiled control stations, each subdivided into seven standardized intertidal levels, were carried out in Chedabucto Bay. Seventy-one species were found, 14 unique to control and 9 to oiled locations. Species diversity was uniformly higher at control than oiled stations. No differences in horizontal zonation of major species were apparent. Analysis of abundance and biomass data for the eight stations and seven tidal levels showed a significant overall difference between oiled and control situations. However, no particular station or tidal level was significantly different from any other. Ten species accounted for most of the variance between oiled and control stations. Six of these were more important at controls and four more important at oiled stations. The flora were particularly affected at oiled stations and species dominant on both sedimentary and rocky shores at all but the lowest tidal levels have been reduced. Length and weight data for the clam Mya arenaria showed significantly lower values at oiled stations, but that for the periwinkle Littorina littorea showed the opposite. The length–weight relationship for both of these species showed a significantly lower increase in weight per unit of length at oiled than at control stations. Oiled stations showed significantly greater concentrations of oil in biota and sediments than unoiled, where concentrations were essentially at background levels. Key words: hydrocarbon, intertidal community, petroleum, pollution, sediment
Recovery of Benthic Macrofauna from Chronic Pollution in the Sea Area off a Refinery Plant, Southwest Finland
Authors: Leppäkoski E. J. , Lindström L. S.
Published: April 2011

Quantitative field studies (density, wet weight biomass, Shannon diversity, species richness, evenness of distribution) on benthic sublittoral macrofauna were made in the vicinity of an oil refinery in southwest Finland before and after the installation of a new wastewater treatment plant that reduced the amount of oil and liquid effluents by ca. 90–95%. The number of species and species diversity increased during the 1st and 2nd yr after pollution abatement at the stations close to the former outflows. The amphipods Pontoporeia affinis, Corophium volutator, and C. lacustre, midge larvae of the Chironomus plumosus-group, the oligochaete Tubifex costatus, the polychaetes Harmothoe sarsi and Polydora redeki, and the bivalve Cardium sp. were the most successful recolonizers of the 23 taxa sampled. The strong lethal effect of oil-contaminated sediments upon Chironomus plumosus larvae decreased markedly in laboratory experiments (LT50 was estimated at 7 d in 1973 and at 28 d in 1974; in 1975, 80–90% of the larvae survived for 28 d). Details of postabatement succession are discussed. The results demonstrate not only the recovery from chronic oil pollution but also the degree of ecological damage caused by previous continuous discharge of oil. Key words: Baltic Sea, Chironomus plumosus, macrobenthos, oil pollution, pollution abatement, recolonization, sediment biotests
Estimation of Functional Responses of Predators on Juvenile Salmon
Authors: Peterman Randall M. , Gatto Marino
Published: April 2011

Several studies have shown that predators can eat large portions (up to 85%) of emerging salmon (Oncorhynchus spp.) fry populations. To understand salmon population dynamics and the effect of salmon enhancement projects, it is necessary to determine how present predation mortality varies with prey density. To predict the shape of this relation outside the range of past observations, we must examine the basic components of the predation process, the functional and numerical responses. A review of past, sparse data on the functional response component shows that predators of salmon fry and smolts were mostly not being saturated (i.e. maximum attack rates were not being achieved) at high prey densities. A method to estimate functional responses from certain types of existing field data is derived and applied to Hooknose Creek pink salmon (O. gorbuscha) and chum salmon (O. keta) information. Results from 7 out of 9 yr corroborate earlier observations that predators are normally operating on the low end of their functional response curves and are therefore capable of causing high mortality on larger prey populations. Also, competition among predators is demonstrated to be significant, resulting in changes in slopes of functional responses. More experimental studies of functional responses are needed, and such research should be carried out in conjunction with perturbations in salmon fry abundance which will result from enhancement projects. Key words: salmon fry, predation, freshwater survival, enhancement, functional response, predator competition
Scanning and Transmission Electron Microscopic Observations of Rainbow Trout (Salmo gairdneri) Gill
Authors: Kendall Michael W. , Dale James E.
Published: April 2011

The rainbow trout (Salmo gairdneri) gill was examined with scanning (SEM) and transmission (TEM) electron microscopic techniques as well as an improved glycol methacrylate embedding procedure for light microscopy. The gill epithelium on primary and secondary lamellae contained distinctive surface features consisting of whorled patterns of ridges (microfolds) with intervening grooves, measurements of which were correlated with measurements obtained from TEM tissue sections. The SEM and TEM data complimented each other concerning physical measurements and presence of lamellar ridges and grooves. The microfolds consisted of cellular membrane evaginations with furrows (grooves) between adjacent microfolds. The ridges and grooves on the primary lamellar surface were quite regular in their architecture whereas the ridges of secondary lamellae were farther apart and discontinuous. The gill raker surface also contained low ridges in a whorled pattern with wide intervening grooves. Small pores of variable diameter were observed on the secondary lamellar surface and much larger pores occurred on the primary lamellar and gill raker surface. TEM sections revealed the presence of chloride, pillar I and II, and epithelial cells and the fine structure of their relationship to the capillary bed. These observations were discussed with reference to their possible adaptive value to the trout. Key words: rainbow trout, branchial epithelium, primary lamella, secondary lamella, pillar cell, scanning electron microscopy, transmission electron microscopy
Molting, Movement, and Dispersion in the Freshwater Prawn Macrobrachium rosenbergii
Authors: Peebles John B.
Published: April 2011

Movement and dispersion patterns of the giant freshwater prawn Macrobrachium rosenbergii were assessed through sonic tagging and a novel quadrate sampling technique. Females moved greater distances at night than males, and females exhibited a weaker tendency than males to return to a home site. Reproductive condition and proximity to ecdysis were related to the distance females moved at night. Environmental heterogeneity, productivity, and habitat utilization differed between two ponds. In the more heterogeneous environment, late premolt and early postmolt prawns were apparently avoiding hard intermolt and early premolt prawns by occupying a less preferred habitat of deep, soft mud. Key words: Dispersion, habitat utilization, home range, Macrobrachium rosenbergii
Metals in the Molluscan Kidney: A Comparison of Two Closely Related Bivalve Species (Argopecten), Using X-Ray Microanalysis and Atomic Absorption Spectroscopy
Authors: Carmichael N. G. , Squibb K. S. , Fowler B. A.
Published: April 2011

The kidney epithelial cells of Argopecten irradians contain concretions that occur within an apical vacuole in these cells and that have been analyzed in situ by energy dispersive X-ray microanalysis. Pellets of these concretions prepared from A. irradians and A. gibbus were compared by X-ray microanalysis and atomic absorption spectrophotometry; calcium and phosphorus were the major elements present in both species, but A. irradians contained higher amounts of magnesium and lower amounts of manganese and zinc than A. gibbus when expressed relative to calcium content. However, A. gibbus contained a smaller proportion of calcium by weight than A. irradians, and A. gibbus contained much higher levels of Cd, Cu, and Cr than A. irradians. The trace metal content of scallop kidney concretions may be a sensitive monitor of marine metal contamination provided that sufficient base line data are collected and individual, species, seasonal, and geographical variability are taken into account. Key words: bivalvia, kidney, metals, analysis, calcification, morphology
ELECTRONIC STRUCTURE OF GRAPHENE NANORIBBONS SUBJECTED TO TWIST AND NONUNIFORM STRAIN
Authors: DOBRINSKY A. , SADRZADEH A. , YAKOBSON B. I. , XU J.
Published: April 2011

Graphene nanoribbons exhibit band gap modulation when subjected to strain. While band gap creation has been theoretically investigated for uniaxial strains, other deformations such as nanoribbon twist have not been considered. Our main objective in this paper is to explore band gap opening in twisted graphene nanoribbons that have metallic properties under tight-binding approximation. While simple considerations based on the Hückel model allow to conclude that zigzag graphene nanoribbons exhibit no band gap when subjected to twist, the Hückel model overall may be inaccurate for band gap prediction in metallic nanoribbons. We utilize Density Functional Theory Tight-Binding Approximation together with a requirement that energy of twisted nanoribbons is minimized to evaluate band gap of metalic armchair nanoribbons. Besides considering twisting deformations, we also explore the possibility of creating band gap when graphene nanoribbons are subject to inhomogeneous deformation such as sinusoidal deformations.
Unchanged OCV Requires Concepts Considering Electrode Degradation Using Sm-Doped Ceria Electrolytes in SOFCs
Authors: Miyashita T.
Published: April 2011

Numerous efforts have been made to solve the basic transport equation that describes a solid-oxide fuel cell (SOFC) with mixed ionic and electronic conductors (MIECs). The open circuit voltage (OCV) is calculated by Wagner’s equation. A current (I) – voltage (V) relationship accounting for electrode polarization voltage losses was developed. However, every electrode degrades with time. Thus, I-V calculations considering electrode degradation using Sm-doped ceria (SDC) electrolytes is described. This method is successful in treating electrode degradation with time. However, the unchanged OCV requires new concepts in the evaluation of electrode degradation. Furthermore, new concepts will be necessary to improve the model of Riess.
The “cryptic” mechanism of action of glucagon-like peptide-2
Authors: Rowland Katherine J. , Brubaker Patricia L.
Published: April 2011

Glucagon-like peptide-2 (GLP-2) is a peptide hormone with multiple beneficial effects on the intestine, including expansion of the mucosal surface area through stimulation of crypt cell proliferation, as well as enhancement of nutrient digestion and absorption. Recent advances in clinical trials involving GLP-2 necessitate elucidation of the exact signaling pathways by which GLP-2 acts. In particular, the GLP-2 receptor has been localized to several intestinal cell types that do not include the proliferating crypt cells, and the actions of GLP-2 have thus been linked to a complex network of indirect mediators that induce diverse signaling pathways. The intestinotropic actions of GLP-2 on the colon have been shown to be mediated through the actions of keratinocyte growth factor and insulin-like growth factor (IGF)-2, whereas small intestinal growth has been linked to IGF-1, IGF-2, and ErbB ligands, as well as the IGF-1 receptor and ErbB. The cellular source of these mediators remains unclear, but it likely includes the intestinal subepithelial myofibroblasts. Conversely, the anti-inflammatory and blood flow effects of GLP-2 are dependent on vasoactive intestinal polypeptide released from submucosal enteric neurons and nitric oxide, respectively. Finally, recent studies have suggested that GLP-2 not only modulates intestinal stem cell behavior but may also promote carcinogenesis in models of sporadic colon cancer. Further consideration of the molecular cross-talk and downstream signaling pathways mediating the intestinotropic effects of GLP-2 is clearly warranted.
High-Throughput RNAi Screening Reveals Novel Regulators of Telomerase
Authors: Cerone Maria Antonietta , Burgess Darren J , Naceur-Lombardelli Cristina , Lord Christopher J. , Ashworth Alan
Published: April 2011

Telomerase is considered an attractive anticancer target on the basis of its common and specific activation in most human cancers. While direct telomerase inhibition is being explored as a therapeutic strategy, alternative strategies to target regulators of telomerase that could disrupt telomere maintenance and cancer cell proliferation are not yet available. Here, we report the findings of a high-throughput functional RNA interference screen to globally profile the contribution of kinases to telomerase activity (TA). This analysis identified a number of novel telomerase modulators, including ERK8 kinase, whose inhibition reduces TA and elicited characteristics of telomere dysfunction. Given that kinases represent attractive drug targets, we addressed the therapeutic implications of our findings, such as demonstrating how limiting TA via kinase blockade could sensitize cells to inhibition of the telomere-associated protein tankyrase. Taken together, our findings suggest novel combinatorial approaches to targeting telomere maintenance as a strategy for cancer therapy. Cancer Res; 71(9); 3328–40. ©2011 AACR.
Association of Specific Genotypes in Metastatic Suppressor HTPAP with Tumor Metastasis and Clinical Prognosis in Hepatocellular Carcinoma
Authors: Ren Ning , Wu Jin-Cai , Dong Qiong-Zhu , Sun Hai-Jing , Jia Hu-Liang , Li Guo-Cai , Sun Bing-Sheng , Dai Chun , Shi Jiong , Wei Jin-Wang , Sheng Yuan-Yuan , Zhou Hai-Jun , Ye Qing-Hai , Qin Lun-Xiu
Published: April 2011

The phosphatidic acid phosphatase HTPAP has been defined as a metastatic suppressor of hepatocellular carcinoma (HCC), but little is known about its function or potential applications as a prognostic marker. In this study, we analyzed patterns of HTPAP genetic variation and gene expression in 864 patients who underwent HCC resection, assessing these patterns for correlations to tumor metastasis potential. Focusing on two tagSNPs that were selected (+357G/C and +1838A/G), we found that only the +357G/C genotype was significantly associated with HTPAP mRNA and protein expression levels and the probability of metastasis. In an independent cohort of 665 HCC patients, we determined that the +357G/C genotype was associated with shorter time to recurrence and overall survival. Together, these results indicated that the HTPAP tagSNP +357 GG+GC genotypes may influence HCC metastatic potential and clinical prognosis by down-regulating HTPAP expression. Extending these results, a global expression profiling analysis identified 41 genes including the pro-inflammatory genes IL-8 and TLR2 that were significantly overexpressed in the +357 GG+GC group, as possible coregulated markers with HTPAP. Together, our findings identify an HTPAP genotype and associated gene expression pattern that favors metastasis progression and that could be used to predict tumor metastasis and prognosis in HCC patients. Cancer Res; 71(9); 3278–86. ©2011 AACR.
Protein Kinase D3 Sensitizes RAF Inhibitor RAF265 in Melanoma Cells by Preventing Reactivation of MAPK Signaling
Authors: Chen Jian , Shen Qiong , Labow Mark , Gaither L. Alex
Published: April 2011

RAS mutations occur in more than 30% of all human cancers but efforts to directly target mutant RAS signaling as a cancer therapy have yet to succeed. As alternative strategies, RAF and MEK inhibitors have been developed to block oncogenic signaling downstream of RAS. As might be expected, studies of these inhibitors have indicated that tumors with RAS or BRAF mutations display resistance RAF or MEK inhibitors. In order to better understand the mechanistic basis for this resistance, we conducted a RNAi-based screen to identify genes that mediated chemoresistance to the RAF kinase inhibitor RAF265 in a BRAF (V600E) mutant melanoma cell line that is resistant to this drug. In this way, we found that knockdown of protein kinase D3 (PRKD3) could enhance cell killing of RAF and MEK inhibitors across multiple melanoma cell lines of various genotypes and sensitivities to RAF265. PRKD3 blockade cooperated with RAF265 to prevent reactivation of the MAPK signaling pathway, interrupt cell cycle progression, trigger apoptosis, and inhibit colony formation growth. Our findings offer initial proof-of-concept that PRKD3 is a valid target to overcome drug resistance being encountered widely in the clinic with RAF or MEK inhibitors. Cancer Res; 71(12); 4280–91. ©2011 AACR.
Sirtuin 1 Is Upregulated in a Subset of Hepatocellular Carcinomas where It Is Essential for Telomere Maintenance and Tumor Cell Growth
Authors: Chen Juan , Zhang Bin , Wong Nathalie , Lo Anthony W.I. , To Ka-Fai , Chan Anthony W.H. , Ng Margaret H.L. , Ho Cecilia Y.S. , Cheng Suk-Hang , Lai Paul B.S. , Yu Jun , Ng Ho-Keung , Ling Ming-Tat , Huang Ai-Long , Cai Xue-Fei , Ko Ben C.B.
Published: April 2011

Hepatocellular carcinoma (HCC) is a highly malignant tumor with a poor prognosis. Treatment of HCC is complicated by the fact that the disease is often diagnosed at an advanced stage when it is no longer amenable to curative surgery, and current systemic chemotherapeutics are mostly inefficacious. Sirtuin 1 (SIRT1) is a class III histone deacetylase that is implicated in gene regulations and stress resistance. In this study, we found that SIRT1 is essential for the tumorigenesis of HCC. We showed that although SIRT1 was expressed at very low levels in normal livers, it was overexpressed in HCC cell lines and in a subset of HCC. Tissue microarray analysis of HCC and adjacent nontumoral liver tissues revealed a positive correlation between the expression levels of SIRT1 and advancement in tumor grades. Downregulation of SIRT1 consistently suppressed the proliferation of HCC cells via the induction of cellular senescence or apoptosis. SIRT1 silencing also caused telomere dysfunction–induced foci and nuclear abnormality that were clearly associated with reduced expressions of telomerase reverse transcriptase (TERT), and PTOP, which is a member of the shelterin complex. Ectopic expression of either TERT or PTOP in SIRT1-depleted cells significantly restored cell proliferation. There was also a positive correlation between the level of induction of SIRT1 and PTOP in human HCC. Finally, SIRT1-silencing sensitized HCC cells to doxorubicin treatment. Together, our findings reveal a novel function for SIRT1 in telomere maintenance of HCC, and they rationalize the clinical exploration of SIRT1 inhibitors for HCC therapy. Cancer Res; 71(12); 4138–49. ©2011 AACR.
Prospective Analysis of Parametric Response Map–Derived MRI Biomarkers: Identification of Early and Distinct Glioma Response Patterns Not Predicted by Standard Radiographic Assessment
Authors: Galbán Craig J. , Chenevert Thomas L. , Meyer Charles R. , Tsien Christina , Lawrence Theodore S. , Hamstra Daniel A. , Junck Larry , Sundgren Pia C. , Johnson Timothy D. , Galbán Stefanie , Sebolt-Leopold Judith S. , Rehemtulla Alnawaz , Ross Brian D.
Published: April 2011

Purpose: Currently, radiologic response of brain tumors is assessed according to the Macdonald criteria 10 weeks from the start of therapy. There exists a critical need to identify nonresponding patients early in the course of their therapy for consideration of alternative treatment strategies. Our study assessed the effectiveness of the parametric response map (PRM) imaging biomarker to provide for an earlier measure of patient survival prediction.

Experimental Design: Forty-five high-grade glioma patients received concurrent chemoradiation. Quantitative MRI including apparent diffusion coefficient (ADC) and relative cerebral blood volume (rCBV) maps were acquired pretreatment and 3 weeks midtreatment on a prospective institutional-approved study. PRM, a voxel-by-voxel image analysis method, was evaluated as an early prognostic biomarker of overall survival. Clinical and conventional MR parameters were also evaluated.

Results: Multivariate analysis showed that PRMADC+ in combination with PRMrCBV− obtained at week 3 had a stronger correlation to 1-year and overall survival rates than any baseline clinical or treatment response imaging metric. The composite biomarker identified three distinct patient groups, nonresponders [median survival (MS) of 5.5 months, 95% CI: 4.4–6.6 months], partial responders (MS of 16 months, 95% CI: 8.6–23.4 months), and responders (MS has not yet been reached).

Conclusions: Inclusion of PRMADC+ and PRMrCBV− into a single imaging biomarker metric provided early identification of patients resistant to standard chemoradiation. In comparison to the current standard of assessment of response at 10 weeks (Macdonald criteria), the composite PRM biomarker potentially provides a useful opportunity for clinicians to identify patients who may benefit from alternative treatment strategies. Clin Cancer Res; 17(14); 4751–60. ©2011 AACR.
Inclusion of Patients with Brain Metastases in Phase I Trials: An Unmet Need
Authors: Gounder Mrinal M. , Spriggs David R.
Published: April 2011

Patients with brain metastases are increasing in number; however, these patients are often excluded in phase I/II trials due to perceived poor prognosis, risk of hemorrhage, inefficient drug delivery, and confounding toxicities. Tsimberidou and colleagues demonstrate that selected patients can be appropriately enrolled in phase I trials and have outcomes representative of the general cancer population. Clin Cancer Res; 17(12); 3855–7. ©2011 AACR.
Hypothermic ante situm Resection in Tumors of the Hepatocaval Confluence
Authors: Mehrabi Ari , Fonouni Hamid , Golriz Mohammad , Hofer Stefan , Hafezi Mohammad , Rahbari Nuh N. , Weitz Jürgen , Büchler Markus W. , Schmidt Jan
Published: April 2011

Primary liver malignancies together with metastatic liver tumors are among the most common tumors in human. The best available treatment option for these diseases is surgical resection. One major parameter which had been considered as contraindication for liver resection owing to technical difficulties in achieving tumor-free margins was the involvement of the hepatocaval confluence. To overcome this problem, several techniques including hypothermic in situ, ante situm and ex situ liver resection have been introduced. The common basis for these liver resections is the total vascular exclusion of the liver, and perfusion of the organ by preservation solution under hypothermic conditions. The major indications for the ante situm liver resection are tumors in the liver that are either unresectable or inadequately resectable by conventional surgery because they involve the venous confluence and/or the retrohepatic vena cava, or are in close proximity to them. This technique is a realistic option to achieve surgical cure or substantial gain of life time with quality of life in otherwise unresectable tumors of the liver. Due to fewer anastomoses, the ante situm approach is easier and safer than the ex situ approach, with an acceptable morbidity and mortality rate. Patient selection is of utmost importance to achieve a good outcome. To minimize the postoperative morbidities and mortality, this procedure requires a multidisciplinary approach and should be performed in experienced centers with a high case volume of hepatobiliary surgeries.
Laparoscopic Liver Resection for Hepatocellular Carcinoma in Cirrhosis: Long-Term Outcomes
Authors: Belli Giulio , Fantini Corrado , Belli Andrea , Limongelli Paolo
Published: April 2011

Background:Few data regarding survival or pattern of recurrence after laparoscopic liver resection (LLR) for hepatocellular carcinoma (HCC) on cirrhosis have been reported so far. Methods: A retrospective analysis of a prospectively maintained database of 109 laparoscopic interventional procedures performed for HCC in cirrhotic liver between 2000 and 2008 was conducted. Results: Sixty-five patients underwent an LLR. Morbidity rates were 20% (13/65), whereas there was only 1 death (1.5%). Reoperation was required in 2 patients. The overall mean postoperative hospital stay was 8.2 (2.6; 3–15) days. The actuarial overall 1-, 3-, and 5-year survival rates were 95, 70, and 55%, respectively, with a median overall survival of 75 months. Excluding the one hospital death, the actuarial 1-, 3-, and 5-year disease-free survival rates were 81, 62, and 32%, respectively, with a median overall disease-free survival of 42 months (95% confidence interval, CI: 18–65). On multivariate analysis, tumor grade (OR: 3.5, 95% CI: 1.1–10.7, p = 0.026) and microvascular invasion (OR: 4.9, 95% CI: 1.2–18.8, p = 0.020) resulted as independent predictors of overall survival. On multivariate analysis, gender (OR: 3.4, 95% CI: 1.1–10.2, p = 0.023), satellite tumor (OR: 4.3, 95% CI: 1.5–12.3, p = 0.006), microvascular invasion (OR: 3.3, 95% CI: 1.0–10.1, p = 0.036) and surgical margin (OR: 3.7, 95% CI: 1.0–10.1, p = 0.036) were identified as independent prognostic predictors of better disease-free survival. After a median follow-up of 29 (range 3–81) months, 31 (48%) out of 64 patients had recurrence. The cumulative recurrence rates at 1, 3, and 5 years were 19, 39, and 68%, respectively. Conclusion: This prospective observational study has confirmed the feasibility and safety of LLR in selected patients with HCC in cirrhotic liver, and proved that it can warrant long-term outcome similar to those reported with the traditional open approach.
Ocular Vestibular Evoked Myogenic Potentials: Frequency Tuning to Air-Conducted Acoustic Stimuli in Healthy Subjects and Ménière’s Disease
Authors: Winters Stephanie M. , Berg Ingvar T.B. , Grolman Wilko , Klis Sjaak F.L.
Published: April 2011

Ocular vestibular evoked myogenic potentials (oVEMP) in response to 250-, 500- and 1000-Hz air-conducted short tone bursts were studied in 22 healthy subjects and 37 Ménière’s disease patients. The goal of this study was to investigate normal tuning characteristics of the oVEMP and the possible oVEMP changes with respect to frequency dependence in Ménière’s disease. In unilateral Ménière’s disease patients, a distinction was made between affected ears and unaffected ears. It was found that in normal subjects, the oVEMP tunes to a stimulus frequency of 500 Hz, with the highest amplitude and lowest threshold at this particular frequency. Generally, Ménière’s disease patients showed lower amplitudes and higher thresholds than normal subjects at all 3 stimulus frequencies in both the affected and the unaffected ear. Additionally, for ears affected by Ménière’s disease, the best stimulus frequency was 1000 Hz. With the use of this altered tuning for these ears, we tried to find a criterion for distinguishing normal from Ménière’s disease ears.
Amyloid β Enhances Migration of Endothelial Progenitor Cells by Upregulating CX3CR1 in Response to Fractalkine, Which May Be Associated With Development of Choroidal Neovascularization
Authors: Wang Jiying , Ohno-Matsui Kyoko , Nakahama Ken-ichi , Okamoto Aikou , Yoshida Takeshi , Shimada Noriaki , Mochizuki Manabu , Morita Ikuo
Published: April 2011

Objective—

Deposits that accumulate beneath retinal pigment epithelium, called drusen, are early signs of age-related macular degeneration (AMD). We have shown that amyloid β (Aβ) is present in drusen, and Aβ may be involved in AMD development. We have also shown that endothelial progenitor cells (EPCs) may contribute to the development of choroidal neovascularization (CNV). Thus, the purpose of this study was to investigate the role played by CX3CR1, a chemokine receptor, in EPC migration and CNV formation.

Methods and Results—

EPCs collected from human umbilical cords were found to express higher levels of CX3CR1 than human umbilical vein endothelial cells, and exposure of EPCs to Aβ caused further upregulation of CX3CR1. This upregulation was decreased by blocking fractalkine, a ligand of CX3CR1. Exposure of EPCs to fractalkine increased their migration, but pretreatment with Aβ enhanced the migration. The fractalkine-induced EPC migration was more inhibited by EPCs derived from CX3CR1
−/−
mice than wild-type mice. The area of laser-induced CNV was significantly smaller in wild-type mice that received bone marrow transplantation from CX3CR1
−/−
mice than in those that received transplantation from wild-type mice.

Conclusion—

These data suggest that Aβ enhances EPC migration through the upregulation of CX3CR1. This upregulation might play a role in development of CNV.