bluuebunny/crossref_metadata_2025 huggingface dataset:
Building Our Future: A Plea for Leadership
Authors: Souba Wiley W.
Published: April 2004

In recent years the spastic nature of the health care marketplace has continued to increase, which has greatly escalated the demands of leadership in academic medical centers. The expectations of leaders, including surgery chairs, have increased considerably, whereas their capacity for independent action has undeniably diminished. In such a predicament, it is useful to revisit fundamentals, using them as a guide to build a sound future. Five leadership principles are critical to building a better future: (1) recognizing that the work of leadership involves an inward journey of self‐discovery and self‐development; (2) establishing clarity around a set of core values that guide the organization as it pursues its goals; (3) communicating a clear sense of purpose and vision that inspires widespread commitment to a shared sense of destiny; (4) building a culture of excellence and accountability throughout the entire organization; and (5) creating a culture that emphasizes the development of leaders and leadership as an organizational capacity. Leadership and learning are inextricably linked. We must change the perception that learning in academic surgery is about correcting a deficit rather than a natural part of human growth and development. Our ability to learn, grow, and contribute to an organization is what provides each of us with meaning and identity. This feeling of being part of something special that is larger than ourselves is a powerful force and an important dividend of great leadership.
Molecular and functional analysis of Caenorhabditis elegans CHIP, a homologue of Mammalian CHIP
Authors: Khan Liakot A , Nukina Nobuyuki
Published: April 2004

A recently identified molecule C‐terminus of Hsc70 interacting protein (CHIP) has been reported to be an E3 ubiquitin ligase collaborating with molecular chaperones for the degradation of misfolded or unfolded proteins. The physiological roles of CHIP in animal and plant development remain largely unknown. Here, we show that the knockdown of CeCHIP by RNAi and knockout by a deletion mutation arrests the development of the animal at the larval stage. CeCHIP expresses ubiquitously in all tissues but there are tissue specific variations of expression level. CeCHIP produces dose dependent phenotypes in vivo. Over expression of CHIP causes embryonic lethality, while a comparatively lower level of over expression causes locomotion and egg laying defects, and the CHIP over expressed animals form dauers at a higher temperature.
Identification of a novel protein 3a from severe acute respiratory syndrome coronavirus
Authors: Yu Chia-Jung , Chen Yee-Chun , Hsiao Cheng-Hsiang , Kuo Tse-Chun , Chang Shin C. , Lu Chun-Yi , Wei Wen-Chin , Lee Chia-Huei , Huang Li-Min , Chang Ming-Fu , Ho Hong-Nerng , Lee Fang-Jen S.
Published: April 2004

The open reading frame 3 of the severe acute respiratory syndrome coronavirus (SARS‐CoV) genome encodes a predicted protein 3a, consisting of 274 amino acids, that lacks any significant similarities to any known protein. We generated specific antibodies against SARS protein 3a by using a synthetic peptide (P2) corresponding to amino acids 261–274 of the putative protein. Anti‐P2 antibodies and the sera from SARS patients could specifically detect the recombinant SARS protein 3a expressed in Escherichia coli and in Vero E6 cells. Expression of SARS protein 3a was detected at 8–12 h after infection and reached a higher level after ∼24 h in SARS‐CoV‐infected Vero E6 cells. Protein 3a was also detected in the alveolar lining pneumocytes and some intra‐alveolar cells of a SARS‐CoV‐infected patient's lung specimen. Recombinant protein 3a expressed in Vero E6 cells and protein 3a in the SARS‐CoV‐infected cells was distributed over the cytoplasm in a fine punctate pattern with partly concentrated staining in the Golgi apparatus. Our study demonstrates that SARS‐CoV indeed expresses a novel protein 3a, which is present only in SARS‐CoV and not in other known CoVs.
Ion channel‐like activity of the antimicrobial peptide tritrpticin in planar lipid bilayers
Authors: Salay Luiz C. , Procopio Joaquim , Oliveira Eliandre , Nakaie Clovis R. , Schreier Shirley
Published: April 2004

The cationic peptide tritrpticin (VRRFPWWWPFLRR, Trp3) has a broad action spectrum, acting against Gram‐positive and Gram‐negative bacteria, as well as some fungi, while also displaying hemolytic activity. We have studied the behavior of Trp3 in planar lipid bilayers (or black lipid membrane – BLM) and were able to demonstrate its ion channel‐like activity. Channel‐like activity was observed in negatively charged azolectin BLM as a sudden appearance of discrete current fluctuations upon application of a constant voltage across the membrane. Trp3 formed large conductance channels (500–2000 pS) both at positive and negative potentials. In azolectin bilayers, the predominant ion‐channel activity was characterized by very regular and discrete current steps (corresponding to openings) of uniform amplitude, which exhibited relatively long residence times (of the order of seconds). Occasionally, multiple conductance steps were observed, indicating the simultaneous presence of more than one open pore. In bilayers of zwitterionic diphytanoylphosphatidyl choline (DPhPC) Trp3 also showed ion‐channel activity, but in a much less frequent and less prominent way. Studies of ion selectivity indicated that Trp3 forms a cation‐selective channel. These results should contribute to the understanding of the molecular interactions and mechanism of action of Trp3 in lipid bilayers and biological membranes.
Analysis of the S. pombe signalling scaffold protein Cdc11p reveals an essential role for the N‐terminal domain in SIN signalling
Authors: Krapp Andrea , Cano Elena , Simanis Viesturs
Published: April 2004

The initiation of cytokinesis in the fission yeast Schizosaccharomyces pombe is signalled by the septation initiation network (SIN). Signalling originates from the spindle pole body (SPB), where SIN proteins are anchored by a scaffold composed of cdc11p and sid4p. Cdc11p links the other SIN proteins to sid4p and the SPB. Homologues of cdc11p have been identified in Saccharomyes cerevisiae (Nud1p) and human cells (Centriolin). We have defined functional domains of cdc11p by analysis of deletion mutants. We demonstrate that the C‐terminal end of cdc11p is necessary for SPB localisation. We also show that the N‐terminal domain is necessary and sufficient for signal transduction, since tethering of this domain to the SPB will substitute for cdc11p in SIN function.
Zonal and topographical differences in articular cartilage gene expression
Authors: Darling Eric M. , Hu Jerry C. Y. , Athanasiou Kyriacos A.
Published: April 2004

Articular cartilage is composed of phenotypically different zones. In young articular cartilage, there are only two distinct zones: superficial and growth. The zones have different mechanical properties and play specific roles within functional cartilage tissue. In small animal models, it is difficult to separate the zones quickly and efficiently using only a dissecting microscope. Surface abrasion is a method that has been developed to harvest cells from articular cartilage to produce highly purified samples in a simple, reproducible process. Using this harvesting technique, the superficial zone has been separated from the underlying growth zone. Superficial cells comprised approximately 4% of the total cells obtained. Superficial and growth zone chondrocytes from articular cartilage were analyzed using real‐time RT‐PCR. Expressed superficial zone protein was 3‐fold greater in the superficial zone population than in the growth zone population (p < 0.01). This, along with histological evidence, indicates that surface abrasion is successful as a zonal separation technique. Additionally, type II collagen was expressed 8‐fold more abundantly in the growth zone than in the superficial zone (p < 0.005). There was no difference in aggrecan expression between the two zones. Regional variations among the femoral groove and medial and lateral condyles were also examined. No significant variations in SZP, type II collagen, or aggrecan were found, which makes the pooling of zonal cells from different regions an acceptable option for tissue engineering studies. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Geometry and state of stress of the Wadati‐Benioff zone in the Gulf of Tehuantepec, Mexico
Authors: Bravo Hugo , Rebollar Cecilio J. , Uribe Antonio , Jimenez Oscar
Published: April 2004

Data recorded in the Gulf of Tehuantepec and published moment tensor solutions were used to infer the geometry of the Wadati‐Benioff zone (W‐B zone) and the stress distribution of the subducted Cocos Plate. From northwest to southeast the subducted slab gently increases its dip, bends up at depths of the order of 100 km and about 240 km inland from the trench, then unbends and increases its dip toward the southeast below Chiapas. Contour lines of equal depth at 50 and 100 km show a significant contortion of the W‐B zone west of the Isthmus of Tehuantepec and coincide with significant changes in the topographic features of the crust. We calculated aVp/Vsratio of 1.75 for the whole area and a Moho depth in the Gulf of Tehuantepec of 28.5 ± 3.5 km. Near the trench, along the coupling zone,Taxes of interplate and intraplate earthquakes are oblique to the interface and parallel to the dip direction of the subducted plate, respectively. At depths greater than 50 km theTaxes are roughly horizontal. Best fit stresses using theGephart and Forsyth[1984]code resulted in the following variation of the minimum stresses (Taxes) from northwest to southeast as (plunge, azimuth) σ3(40°, 37°) to σ3(28°, 72°), then to σ3(11°, 54°) and finally to σ3(27°, 35°). We also analyzed recordings from the 30 September 1999, Oaxaca earthquakeMw= 7.5 and its aftershocks. We inferred an approximate fault area of 80 by 30 km inside the subducted Cocos Plate.
Array Decomposition‐Fast Multipole Method for finite array analysis
Authors: Kindt Rick W. , Volakis John L.
Published: April 2004

An innovative approach is presented for analyzing finite arrays of regularly spaced elements. We review the recently proposed Array Decomposition Method, which exploits the block‐Toeplitz property of regularly spaced arrays for significant storage reduction. To further reduce storage, in this paper we incorporate a multipole expansion to treat distant element interactions. The suggested approach overcomes the matrix storage bottleneck associated with integral equation methods, resulting in fixed and minimal matrix storage for any sized array (on the same order as the storage of a single array element). Hence, fast and rigorous analysis of very large finite arrays can be accomplished with limited resources.
Geologic context of geodetic data across a Basin and Range normal fault, Crescent Valley, Nevada
Authors: Friedrich A. M. , Lee J. , Wernicke B. P. , Sieh K.
Published: April 2004

Geodetic strain and late Quaternary faulting in the Basin and Range province is distributed over a region much wider than historic seismicity, which is localized near the margins of the province. In the relatively aseismic interior, both the magnitude and direction of geodetic strain may be inconsistent with the Holocene faulting record. We document the best example of such a disagreement across the NE striking, ∼55° NW dipping Crescent normal fault, where a NW oriented, 70 km geodetic baseline records contemporary shortening of ∼2 mm/yr orthogonal to the fault trace. In contrast, our geomorphic, paleoseismic, and geochronologic analyses of the Crescent fault suggest that a large extensional rupture occurred during the late Holocene epoch. An excavation across the fault at Fourmile Canyon reveals that the most recent event occurred at 2.8 ± 0.1 ka, with net vertical tectonic displacement of 4.6 ± 0.4 m at this location, corresponding to the release of ∼3 m of accumulated NW‐SE extension. Measured alluvial scarp profiles suggest a minimum rupture length of 30 km along the range front for the event, implying a moment magnitudeMwof at least 6.6. No prior event occurred between ∼2.8 ka and ∼6.4 ± 0.1 ka, the14C calender age of strata near the base of the exposed section. Assuming typical slip rates for Basin and Range faults (∼0.3 mm/yr), these results imply that up to one third, or ∼1 m, of the extensional strain released in the previous earthquake could have reaccumulated across the fault since ∼2.8 ka. However, the contemporary shortening implies that the fault is unloading due to a transient process, whose duration is limited to between 6 years (geodetic recording time) and 2.8 ka (the age of the most recent event). These results emphasize the importance of providing accurate geologic data on the timescale of the earthquake cycle in order to evaluate geodetic measurements.
Nontidal ocean mass loading detected by GPS observations in the tropical Pacific region
Authors: Munekane H. , Matsuzaka S.
Published: April 2004

The effect of nontidal ocean mass loading is investigated as a possible cause for the seasonal variability observed in the vertical components of the GPS‐derived site coordinates of tropical Pacific islands. The nontidal ocean mass origin sea level changes (MOSLCs) are estimated by subtracting the steric height changes observed at buoys from the net sea level changes measured by satellite altimetry. Assuming a linear relationship between the MOSLCs at the closest buoys and the GPS vertical movements, the coherences and the admittances are estimated. We found evidence that the vertical movements are caused by the loading effect at three out of four sites. The occasional deviations between the vertical movements and predicted loading deformations are presumably due to the invalidity of the assumption of a linear relationship between the MOSLCs and the loading deformation and/or of the mean temperature‐salinity relationship used in estimating steric heights in the corresponding periods.
Innate versus adaptive immunity in Candida albicans infection
Authors: Ashman Robert B , Farah Camile S , Wanasaengsakul Siripen , Hu Yan , Pang Gerald , Clancy Robert L
Published: April 2004

Candida albicans is a common opportunistic pathogen, causing both superficial and systemic infection. Clinical observations indicate that mucocutaneous infections are commonly associated with defective cell‐mediated immune responses, whereas systemic infection is more frequently seen in patients with deficiencies in neutrophil number or function. Analysis of mechanisms of host resistance against gastrointestinal and oral infection in mouse models has demonstrated an absolute dependence on CD4+ T cells, although clearance also involves phagocytic cells. Both IL‐12 and TNF‐α appear to be important mediators, but mouse strain‐dependent variations in susceptibility to infection may be related to T‐cell enhancement of production of phagocytic cells by the bone marrow. In murine systemic infection, the role of innate and adaptive responses is less well defined. Studies in immunodeficient and T‐cell‐depleted mice suggest that clearance of the yeast may be predominantly a function of the innate response, whereas the adaptive response may either limit tissue damage or have the potential to cause immunopathology, depending on the host genetic context in which the infection takes place.
Evidence that a mechanism for efficient flavivirus budding upregulates MHC class I
Authors: Lobigs Mario , Müllbacher Arno , Lee Eva
Published: April 2004

An appealing hypothesis for the biological role of flavivirus‐induced, interferon‐independent, upregulation of MHC class I on the surface of infected cells is that of viral immune evasion from NK cell recognition. Here we show that a mechanism for efficient flavivirus morphogenesis interferes with the MHC class I pathway, using a flavivirus budding mutant and recombinant expression of wild‐type and mutant forms of the flavivirus structural proteins. We propose that the phenomenon of flavivirus‐mediated MHC class I upregulation is a by‐product of a unique assembly strategy evolved by flaviviruses and therefore did not evolve primarily as an immune escape mechanism for virus growth in the vertebrate host.
Ovine atadenovirus: a review of its biology, biosafety profile and application as a gene delivery vector
Authors: Both Gerald W
Published: April 2004

The ovine adenovirus isolate OAdV287 is the prototype of the newly recognized genus of atadenoviruses. Although not as well studied as human mastadenoviruses, a substantial amount of work has now been carried out with this virus and an understanding of its interesting and unique properties is beginning to emerge. In this article the biology and biosafety profile of the virus is reviewed. This knowledge underpins the exploitation of the virus as a gene delivery vector. Its potential as a vaccine vector and its application to the treatment of prostate cancer is summarized and discussed.
Genesis of the strand‐biased signature in somatic hypermutation of rearranged immunoglobulin variable genes
Authors: Steele Edward J , Franklin Andrew , Blanden Robert V
Published: April 2004

The history and current development of the reverse transcriptase model of somatic hypermutation (RT‐model) is reviewed with particular reference to the genesis of strand‐biased mutation signatures in rearranged immunoglobulin variable genes (V(D)J). The recent disagreement in the field as to whether strand bias really exists or not has been critically analysed and the confusion traced to the putative presence, in some mutated V(D)J sequence collections, of polymerase chain reaction (PCR)‐recombinant artefacts. Recent analysis of somatic hypermutation in xeroderma pigmentosum variant patients, by the group of PJ Gearhart and others, has established that the Y‐family translesion DNA repair enzyme, DNA polymerase η (eta), is responsible for the striking A‐T targeted strand‐bias mutation signature seen in all mouse and human collections of somatically mutated V(D)J sequences. This evidence, together with our own recent demonstration that human DNA polymerase η is a reverse transcriptase, leads to the conclusion that the strand‐biased A‐T mutation signature is caused either by: (i) error‐prone DNA‐dependent DNA repair synthesis by pol‐η of single‐strand nicks preferentially in the non‐transcribed strand; and/or (ii) by error‐prone cDNA synthesis of the transcribed strand by pol‐η using the pre‐mRNA as the copying template, primed by the nicked transcribed DNA strand, followed by replacement of the original transcribed strand by cDNA. Analysis of the total mutation pattern also suggests that the major transitions observed in SHM (A→G, C→T and G→A) can be explained by known RNA editing mechanisms active on pre‐mRNA which are then written into cDNA during synthesis of the transcribed strand by error‐prone cellular reverse transcriptases such as pol‐η.
Granzymes in cytolytic lymphocytes − to kill a killer?
Authors: Regner Matthias , Müllbacher Arno
Published: April 2004

Granzymes (gzm) are major components of the granules of cytolytic lymphocytes, natural killer and cytotoxic T cells. Their generally accepted mode of action consists of their directed secretion towards a virus‐infected or neoplastic target cell and perforin‐dependent delivery to the target cell cytosol, where they engage in various actions resulting in target cell apoptosis. Here, based on observations of infection of gzmAxB−/− mice with ectromelia virus, mousepox, we propose an additional − and distinct − function for gzmA and B. In this model, gzm constitute one of the first lines of defence of immune cells against virus infection of immune cells themselves. Accordingly, endogenous gzm interfere with viral replication in cytolytic lymphocytes either directly, as a result of their proteolytic activity, leading to destruction of viral proteins, or indirectly, via: (i) processes akin to the caspase cascade when acting as effector molecules in the induction of target cell apoptosis; or (ii) their capacity to induce early inflammatory mediators. We discuss the predictions of the model in the light of available data.
Exocytosis and Fas mediated cytolytic mechanisms exert protection from West Nile virus induced encephalitis in mice
Authors: Wang Yang , Lobigs Mario , Lee Eva , Müllbacher Arno
Published: April 2004

Infection of mice with the flaviviruses West Nile virus (WNV) and Murray Valley encephalitis (MVE) induces cytolytic T‐cell responses which are highly cross‐reactive on target cells infected with heterologous flaviviruses. Of C57BL/6 mice infected with low doses (102−106 PFU) of either virus, 30−40% develop encephalitis and die within 10−12 days1, 2. Mice with defects in the Fas or granule exocytosis (perforin and granzymes A and B) pathway of cellular cytotoxicity display reduced mortality and increased survival time when infected with MVE and are protected from encephalitis when deficient in both pathways. This contrasts with infection with WNV where defects in these cytolytic mechanisms increase the percentage of mice that succumb to encephalitis. Thus, no generalizations as to protective or detrimental effects of cytolytic effector functions in recovery from closely related flavivirus infections can be made. Virus−host immune interactions have to be assessed individually and cannot be generalized.
Type I IFN‐β gene therapy suppresses cardiac CD8+ T‐cell infiltration during autoimmune myocarditis
Authors: Bartlett Emmalene J , Lenzo Jason C , Sivamoorthy Soruba , Mansfield Josephine P , Cull Vanessa S , James Cassandra M
Published: April 2004

Gene therapy using DNA encoding type I IFN subtypes IFNA6, IFNA9 and IFNB suppresses murine cytomegalovirus (MCMV)‐myocarditis, a predominantly cell‐mediated disease in BALB/c mice. CD8+ T cells are the principal cell type within the inflamed myocardium. As such, we investigated the effects of IFN subtype treatment on this T‐cell subset and other cell types in the cardiac infiltrate. In the acute phase of disease, IFNA6 and IFNA9 treatments significantly reduced the number of CD8+ T cells within the foci of cellular infiltration in the heart. During the chronic phase, which is primarily autoimmune in nature, IFNB treatment significantly reduced CD8+ T cells. B‐cell and neutrophil numbers in the cardiac infiltrate were also reduced following IFNB immunotherapy. Although early inflammatory responses are important for resolution of virus infection, high numbers of lymphocytes persisting in the myocardium may lead to exacerbation of disease. Our data suggests that type I IFN DNA therapy regulates cardiac cellular infiltration. Thus, treatment with IFN‐β administered prophylactically to high‐risk patients in acquiring CMV infection may reduce the development of chronic autoimmune myocarditis.
Estimating photosynthetic light-use efficiency using the photochemical reflectance index: variations among species
Authors: Guo Jianmin , Trotter Craig M.
Published: April 2004

Recent studies have shown that the photochemical reflectance index (PRI), derived from narrow waveband reflectance at 531 and 570 nm, can be used as a remote measure of photosynthetic light-use efficiency (LUE). However, uncertainty remains as to the consistency of the relationship between PRI and LUE across species. In this study we examined the relationship between the PRI and various photosynthetic parameters for a group of species with varying photosynthetic capacity. At constant irradiance, for the species group as a whole, the PRI was well correlated with LUE (r2=0.58) and with several other photosynthetic parameters, but best correlated with the ratio of carotenoids to chlorophylls contents (Caro / Chl). Despite the interspecific trends observed, determination of light response functions for the PRI in relation to photosynthetic parameters revealed that species-specific relationships were clearly stronger. For example, r2>0.90 for species-level PRI / LUE relationships. Also, the species-specific light-response data show that the magnitude of the PRI can be related to the magnitude of the saturated irradiance and the rate of CO2 uptake. As demonstrated here, a light response function provides a simple yet precise approach for characterising the relationship between the PRI and photosynthetic parameters, which should assist with improved evaluation of the usefulness of the PRI as a generalised measure of LUE.
A simple new equation for the reversible temperature dependence of photosynthetic electron transport: a study on soybean leaf
Authors: June Tania , Evans John R. , Farquhar Graham D.
Published: April 2004

The temperature response of Jmax, the irradiance-saturated potential rate of photosynthetic electron transport in the absence of Rubisco limitation, has usually been modelled by a complicated, modified Arrhenius type of equation. Light saturation can be difficult to achieve and reduces the precision of fluorescence measurements. Consequently, we calculated the rate of electron transport at 1200 μmol photosynthetically active radiation (PAR) quanta m–2 s–1 from chlorophyll fluorescence measurements on intact soybean leaves [Glycine max (L.) Merr] as temperature increased from 15 to 43°C with 1250 μmol mol–1 ambient [CO2]. Electron transport rate was maximal around 37°C and the decline in rate following further increases in leaf temperature to 43°C was found to be completely reversible immediately upon return to lower temperatures. We report a convenient, new equation for the temperature dependence of the rate of electron transport under high irradiance:...
Effects of sheep grazing episodes on sediment and nutrient loss in overland flow
Authors: Elliott A. H. , Carlson W. T.
Published: April 2004

The effect of sheep grazing on the loss of sediment and nutrients in overland flow was investigated on a hill-country farm in the Waikato, New Zealand. The losses were measured in runoff produced artificially with small (0.5 m2) and large (1050 m2) rainfall simulators. Immediately after intensive winter grazing, rainfall applied at high intensity increased concentrations by a factor of 13–16 for sediment and particulate nutrients, 33–76 for dissolved reactive phosphorus and ammonium-nitrogen, and 5–7 for dissolved organic nitrogen and phosphorus. During summer, when there was less removal of vegetative cover, there was a smaller effect of grazing. The concentrations of sediment and particulate nutrients in overland flow were strongly correlated with the percentage of bare ground. The concentrations returned to background levels within 6 weeks after grazing, and the infiltration rate and ground cover also recovered from grazing in this time. The small rainfall simulator experiments showed that the infiltration rate decreases with grazing, which results in greater runoff after grazing. The greater runoff combines with the increased concentrations to give higher loads after grazing. In late winter, the infiltration rates were approximately half the summer values and the soil erodibility was approximately double, so the risk of high sediment and nutrient loads is greatest in winter, especially considering the higher rainfall and lower grass growth. The management implications are that exposure of bare ground associated with intensive grazing should be avoided, especially in winter.
Water-stable aggregates of flooded Inceptisols from south-eastern Nigeria in relation to mineralogy and chemical properties
Authors: Igwe Charles A. , Stahr Karl
Published: April 2004

Information on the influence of chemical and mineralogical properties on soil aggregate stability of field soils subjected to waterlogging at some time of the year is essential for better management of these soils. We studied water-stable aggregates (WSA) of various sizes for clay flocculation index, soil organic carbon, total elements, and mineralogy of the soil, and related these properties to aggregate stability. Five soil profiles sited on the floodplain of the River Niger were studied. The topsoils were dominated in all profiles except near the river by WSA�>�2.00�mm. Also the mean-weight diameter (MWD) of the topsoil followed the trend in WSA > 2.00 mm. Thixotropic age hardening appeared to be responsible for the rather high values of WSA > 2.00 and MWD in the topsoil. Soil organic carbon content associated significantly better with macroaggregates than microaggregates. The aggregating effects of the polyvalent cations manifested more on the microaggregates. The stabilising role of various forms of Fe, Al, and Mn oxides is believed to be as result of their large surface area, abundance, and the favourable environment for their formation. These polyvalent metals may have formed bridges between clay and organic matter in the formation of aggregates.
A survey of the cation content of piggery effluents and some consequences of their use to irrigate soils
Authors: Smiles D. E. , Smith C. J.
Published: April 2004

Piggery effluent contains high concentrations of potassium, and its repeated irrigation raises soil exchangeable potassium to levels, relative to divalent cations, that may degrade soil structure. We surveyed 6 big piggeries extending from south-eastern Queensland on a self-mulching Vertosol, to an Arenic Rudosol in south-eastern South Australia. We sampled effluent used for irrigation and also soil profiles to permit 'fenceline' comparisons between soils that had and had not been irrigated. The major water-soluble cations sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) were measured in the effluent and the soil saturation extracts, and also their exchangeable forms on air-dried soil samples. Ammonium-nitrogen (NH4+-N) was also assayed. The effluents were similar, with pH values between 7.5 and 8 together with very high water-soluble NH4-N, lower values for K+ and Na+, and quite low concentrations of Ca2+ and Mg2+. Cation concentrations varied across effluents; sodium and potassium adsorption ratios (SAR and KAR) were relatively constant but smaller than an ammonium adsorption ratio (Am-AR), which we conceive to estimate the influence of NH4+-N relative to the divalent cations in the effluent. Exchangeable K+ ratios in all profiles that had been irrigated were greater than their non-irrigated partners, as were the KAR values in their saturation extracts. Despite high concentrations of NH4+-N and high values of Am-AR in the effluents, there was no evidence of exchangeable NH4+ in the soils when sampled, which, we presume, is rapidly taken up by plants or oxidised. We present data that support a useful relationship between total cation content and effluent and the soil saturation extract electrical conductivity (EC), We also observed a modest increase in the EC of the saturation extract of irrigated soils. Farm records were insufficient to permit material balance calculations.
Dry season suspended sediment concentration and sedimentation in the Richmond River estuary, northern NSW, Australia
Authors: Hossain Shahadat , Eyre Bradley D. , McConchie David
Published: April 2004

Dry season suspended sediment concentration and sedimentation in the Richmond River catchment were investigated during 2 hydrological years (1994–96). Longitudinal suspended sediment transects during low flow months showed that the Richmond River estuary remained well mixed and maintained <30 mg/L suspended sediment concentration without any visible turbidity maximum zone all along the estuary. During the entire dry season, there is very little exchange of suspended sediment between the upper and lower estuaries because of very small input from the upper catchment. The estuary receives net sediment input from the continental shelf during the dry months under normal tidal circulation, and marker horizon core samples confirmed that most of these imported sediments were deposited in the lower estuary; during the 2 dry seasons, lower estuary sedimentation rate varied about 0.84 ± 0.31 cm to 0.48 ± 0.3 cm. Flushing times of the Richmond River estuary show that all point and non-point source inputs of sediments and pollutants into the estuary can be flushed out during one dry season.
Fate and behaviour of pesticides in the agroecosystem—a review with a New Zealand perspective
Authors: Sarmah Ajit K , Müller Karin , Ahmad Riaz
Published: April 2004

Pesticides are indispensable in modern agricultural production; however, their off-site migration and detrimental effects on surface water and groundwater quality cause concern. Current pesticide usage and trend data show pesticide use is widespread in New Zealand. According to national surveys, concentrations of most pesticides in groundwater are usually low, and their occurrence has been attributed to non-point sources of contamination. Although it is well established that the environmental fate of pesticides is governed by complex interactions of many processes such as sorption, degradation, and transport, our understanding of these basic mechanisms in the vadoze zone is too far from complete to predict quantitatively the fate of trace residues of pesticides in various soil types within one geographical location. This is mainly due to the vexing issue of the complex nature of soil and its lateral heterogeneity, such as spatial and temporal variability in field-scale. The use of simulation models to predict the environmental fate of pesticides using laboratory- and field-derived parameters is discussed. The objective of this overview is to present past and recent environmental fate work on pesticides carried out under New Zealand conditions, to provide a wider perspective on the subject matter, and to give some recommendations for future research directions.
Genome-wide RNA interference screen identifies previously undescribed regulators of polyglutamine aggregation
Authors: Nollen Ellen A. A. , Garcia Susana M. , van Haaften Gijs , Kim Soojin , Chavez Alejandro , Morimoto Richard I. , Plasterk Ronald H. A.
Published: April 2004

Protein misfolding and the formation of aggregates are increasingly recognized components of the pathology of human genetic disease and hallmarks of many neurodegenerative disorders. As exemplified by polyglutamine diseases, the propensity for protein misfolding is associated with the length of polyglutamine expansions and age-dependent changes in protein-folding homeostasis, suggesting a critical role for a protein homeostatic buffer. To identify the complement of protein factors that protects cells against the formation of protein aggregates, we tested transgenic
Caenorhabditis elegans
strains expressing polyglutamine expansion yellow fluorescent protein fusion proteins at the threshold length associated with the age-dependent appearance of protein aggregation. We used genome-wide RNA interference to identify genes that, when suppressed, resulted in the premature appearance of protein aggregates. Our screen identified 186 genes corresponding to five principal classes of polyglutamine regulators: genes involved in RNA metabolism, protein synthesis, protein folding, and protein degradation; and those involved in protein trafficking. We propose that each of these classes represents a molecular machine collectively comprising the protein homeostatic buffer that responds to the expression of damaged proteins to prevent their misfolding and aggregation.
The
Arabidopsis
repressor of light signaling, COP1, is regulated by nuclear exclusion: Mutational analysis by bioluminescence resonance energy transfer
Authors: Subramanian Chitra , Kim Byung-Hoon , Lyssenko Nicholas N. , Xu Xiaodong , Johnson Carl Hirschie , von Arnim Albrecht G.
Published: April 2004

Bioluminescence resonance energy transfer (BRET) between
Renilla
luciferase and yellow fluorescent protein has been adapted to serve as a real-time reporter on protein-protein interactions in live plant cells by using the
Arabidopsis
Constitutive photomorphogenesis 1 (COP1) protein as a model system. COP1 is a repressor of light signal transduction that functions as part of a nuclear E3 ubiquitin ligase. COP1 possesses a leucine-rich nuclear-exclusion signal that resides in a domain implicated in COP1 dimerization. BRET was applied in conjunction with site-directed mutagenesis to explore the respective contributions of the nuclear-exclusion and dimerization motifs to the regulation of COP1 activity
in vivo
. One specific mutant protein, COP1
L105A
, showed increased nuclear accumulation but retained the ability to dimerize, as monitored by BRET, whereas other mutations inhibited both nuclear exclusion and COP1 dimerization. Mutant rescue and overexpression experiments indicated that nuclear exclusion of COP1 protein is a rate-limiting step in light signal transduction.
Lactosylceramide recruits PKCα/ε and phospholipase A2to stimulate PECAM-1 expression in human monocytes and adhesion to endothelial cells
Authors: Gong NanLing , Wei Heming , Chowdhury Sanaul Haq , Chatterjee Subroto
Published: April 2004

Despite the importance of platelet/endothelial cell adhesion molecule-1 (PECAM-1, CD31) in the adhesion and diapedesis of monocytes/lymphocytes, little is known about the mechanisms by which it is regulated. We explored the role of a glycosphingolipid, lactosylceramide (LacCer), in modulating PECAM-1 expression and cell adhesion in human monocytes. We observed that LacCer specifically exerted a time-dependent increase in PECAM-1 expression in U-937 cells. Maximal increase in PECAM-1 protein occurred after incubation with LacCer for 60 min. LacCer activated PKCα and -ε by translocating them from cytosol to membrane. This was accompanied by the activation of phospholipase A2(PLA2) and the increase of cell adhesion, which were abrogated by chelerythrine chloride, 2-[1-(3-dimethylaminopropyl)-1H-indol-3-yl]-3-(1H-indol-3-yl)-maleimide and 12-(2-cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo(2,3-a)pyrrolo(3,4-c)-carbazole (GÖ 6976) (PKC inhibitors). Similarly, bromoenol lactone (a Ca2+-independent PLA2inhibitor) and methyl arachidonyl fluorophosphonate (an inhibitor of cytosolic PLA2and Ca2+-independent PLA2) inhibited LacCer-induced PLA2activity. Bromophenacyl bromide (a PLA2inhibitor) abrogated LacCer-induced PECAM-1 expression, and this was bypassed by arachidonic acid. Furthermore, the arachidonate-induced up-regulation of PECAM-1 was abrogated by indomethacin [a cyclooxygenase (COX)-1 and -2 inhibitor] orN-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide (a COX-2 inhibitor) but not nordihydroguaiaretic acid (a lipoxygenase inhibitor). In sum, PKCα/ε are the primary targets for the activation of LacCer. Downstream activation of intracellular Ca2+-independent PLA2and/or cytosolic PLA2results in the production of arachidonic acid, which in turn serves as a precursor for prostaglandins that subsequently stimulate PECAM-1 expression and cell adhesion. These findings may be relevant in explaining the role of LacCer in the regulation of PECAM-1 and related pathophysiology.
Industrial emissions cause extreme urban ozone diurnal variability
Authors: Zhang Renyi , Lei Wenfang , Tie Xuexi , Hess Peter
Published: April 2004

Simulations with a regional chemical transport model show that anthropogenic emissions of volatile organic compounds and nitrogen oxides (NO
x
= NO + NO
2
) lead to a dramatic diurnal variation of surface ozone (O
3
) in Houston, Texas. During the daytime, photochemical oxidation of volatile organic compounds catalyzed by NO
x
results in episodes of elevated ambient O
3
levels significantly exceeding the National Ambient Air Quality Standard. The O
3
production rate in Houston is significantly higher than those found in other cities over the United States. At night, a surface NO
x
maximum occurs because of continuous NO emission from industrial sources, and, consequently, an extensive urban-scale “hole” of surface ozone (<10 parts per billion by volume in the entire Houston area) is formed as a result of O
3
removal by NO. The results suggest that consideration of regulatory control of O
3
precursor emissions from the industrial sources is essential to formulate ozone abatement strategies in this region.
Mapping quantitative traits with random and with ascertained sibships
Authors: Peng Jie , Siegmund D.
Published: April 2004

Use of a robust score statistic based on a variance components model to map quantitative trait loci in randomly sampled pedigrees is reviewed. Sibships ascertained through a single proband are discussed. Under a standard assumption of multivariate normality, two suggested methods of ascertainment correction are shown to be asymptotically equivalent when the number of sibships is large.
A common neuronal code for perceptual processes in visual cortex? Comparing choice and attentional correlates in V5/MT
Authors: Krug Kristine
Published: April 2004

In the past two decades, sensory neuroscience has moved from describing response properties to external stimuli in cerebral cortex to establishing connections between neuronal activity and sensory perception. The seminal studies by Newsome, Movshon and colleagues in the awake behaving macaque firmly link single cells in extrastriate area V5/MT and perception of motion. A decade later, extrastriate visual cortex appears awash with neuronal correlates for many different perceptual tasks. Examples are attentional signals, choice signals for ambiguous images, correlates for binocular rivalry, stereo and shape perception, and so on. These diverse paradigms are aimed at elucidating the neuronal code for perceptual processes, but it has been little studied how they directly compare or even interact. In this paper, I explore to what degree the measured neuronal signals in V5/MT for choice and attentional paradigms might reflect a common neuronal mechanism for visual perception.
Fibroblast growth factors in epithelial repair and cytoprotection
Authors: Braun Susanne , auf dem Keller Ulrich , Steiling Heike , Werner Sabine
Published: April 2004

Growth factors are polypeptides that stimulate the division of certain cell types at low concentrations. Fibroblast growth factor (FGF) 7 (FGF–7) and its homologue FGF–10 act specifically on various types of epithelial cells including keratinocytes of the skin, intestinal epithelial cells and hepatocytes. In addition, FGF–7 and FGF–10 have been shown to be more than growth factors: they can protect epithelial cells from damaging effects induced, for example, by radiation and oxidative stress. Therefore, they are currently in clinical trials for the treatment of oral mucositis, a severe side–effect of cancer therapy characterized by painful inflammation and ulceration of the oral epithelium. To gain insight into the mechanisms of FGF–7/FGF–10 action in epithelial cells, we searched for genes that are regulated by these growth factors. Indeed, we identified genes that help us to explain the mechanisms that underlie the effects of FGF–7. Most interestingly, several genes were identified that are likely to mediate the cytoprotective effect of FGF–7 for epithelial cells
in vitro
and possibly also in injured and diseased tissues
in vivo
.
The scarless heart and the MRL mouse
Authors: Heber–Katz Ellen , Leferovich John , Bedelbaeva Khamilia , Gourevitch Dmitri , Clark Lise
Published: April 2004

The ability to regenerate tissues and limbs in its most robust form is seen in many non–mammalian species. The serendipitous discovery that the MRL mouse has a profound capacity for regeneration in some ways rivalling the classic newt and axolotl species raises the possibility that humans, too, may have an innate regenerative ability. The adult MRL mouse regrows cartilage, skin, hair follicles and myocardium with near perfect fidelity and without scarring. This is seen in the ability to close through–and–through ear holes, which are generally used for lifelong identification of mice, and the anatomic and functional recovery of myocardium after a severe cryo–injury. We present histological, biochemical and genetic data indicating that the enhanced breakdown of scar–like tissue may be an underlying factor in the MRL regenerative response. Studies as to the source of the cells in the regenerating MRL tissue are discussed. Such studies appear to support multiple mechanisms for cell replacement.
Randomized trial of cohesive short‐stretch versus four‐layer bandaging in the management of venous ulceration
Authors: Franks Peter J. , Moody Marion , Moffatt Christine J. , Martin Ruth , Blewett Rachel , Seymour Ellen , Hildreth Anthea , Hourican Catherine , Collins Jeanette , Heron Anita
Published: April 2004

A multicenter prospective randomized clinical trial was undertaken to compare a generic four‐layer bandage system with a cohesive short‐stretch system (Actico, Activa Healthcare) in the management of venous leg ulceration. Both systems are designed to produce sufficient pressure to counteract venous hypertension. Patients in leg ulcer services with leg ulceration were screened for inclusion in this trial. Patients with arterial disease (ankle brachial pressure index < 0.8) and causes of ulceration other than venous disease were excluded. For patients with bilateral ulceration, the limb with the larger area of ulceration was studied. Patients were randomized to receive either type of compression bandage and simultaneously randomized to one of two foam dressings that were changed weekly unless more frequent changes were clinically required. In all, 156 patients met entry criteria and were randomized from the 12 clinical centers with median (range) ulcer size of 4.33 (0.33–123.10) cm2. Analysis revealed that after 24 weeks a total of 111 (71%) of patients had complete ulcer closure, 32 (21%) had withdrawn from the trial, 12 (8%) remained with open ulceration, and one patient had died. Of the 74 patients randomized to the four‐layer bandage, 51(69%) had ulcer closure on treatment compared with 60/82 (73%) on the cohesive short‐stretch system. Intention‐to‐treat analysis produced a hazard ratio for healing of 1.08 (95 percent CI 0.63–1.85, p= 0.79). Withdrawal rates were similar between groups (15, 20% four‐layer bandage; 17, 21% cohesive short‐stretch system). Ulcer closure rates for patients treated with the cohesive short‐stretch system were similar to those for patients managed by the four‐layer bandage system in this trial.
The fibroblast‐populated collagen matrix as a model of wound healing: a review of the evidence
Authors: Carlson Mark A. , Longaker Michael T.
Published: April 2004

The fibroblast‐populated collagen matrix (FPCM) has been utilized as an in vitro model of wound healing for more than 2 decades. It offers a reasonable approximation of the healing wound during the phases of established granulation tissue and early scar. The gross and microscopic morphology of the FPCM and the healing wound are similar at analogous phases. The processes of proliferation, survival/apoptosis, protein synthesis, and contraction act in similar directions in these two models, and the response to exogenous agents also is consistent between them. If its limitations are respected, then the FPCM can be used as a model of the healing wound. (WOUND REP REG 2004;12:–)
New Risk‐Based Capital Standards in the European Union: A Proposal Based on Empirical Data
Authors: Schmeiser Hato
Published: April 2004

Abstract

In response to criticism concerning the current solvency system, the European Commission is developing new rules for insurance companies operating in the member states of the European Union (EU). Under this so‐called Solvency II concept, an insurer is allowed to verify its solvency by using an internal risk management model previously approved by the regulatory authority. In this article we develop such an internal risk management approach for property‐liability insurers that is based on dynamic financial analysis (DFA). The proposed concept uses a simulation technique and models the central risk factors from the investment and underwriting areas of an insurance company. On the basis of the data provided by a German insurer, the ruin probabilities under different scenarios and varying planning horizons are calculated.