bluuebunny/crossref_metadata_2025 huggingface dataset:
Extinction rate, historical population structure and ecological role of the Caribbean monk seal
Authors: McClenachan Loren , Cooper Andrew B
Published: March 2008

The productivity and biomass of pristine coral reef ecosystems is poorly understood, particularly in the Caribbean where communities have been impacted by overfishing and multiple other stressors over centuries. Using historical data on the spatial distribution and abundance of the extinct Caribbean monk seal (Monachus tropicalis), this study reconstructs the population size, structure and ecological role of this once common predator within coral reef communities, and provides evidence that historical reefs supported biomasses of fishes and invertebrates up to six times greater than those found on typical modern Caribbean reefs. An estimated 233 000–338 000 monk seals were distributed among 13 colonies across the Caribbean. The biomass of reef fishes and invertebrates required to support historical seal populations was 732–1018 g m−2of reefs, which exceeds that found on any Caribbean reef today and is comparable with those measured in remote Pacific reefs. Quantitative estimates of historically dense monk seal colonies and their consumption rates on pristine reefs provide concrete data on the magnitude of decline in animal biomass on Caribbean coral reefs. Realistic reconstruction of these past ecosystems is critical to understanding the profound and long-lasting effect of human hunting on the functioning of coral reef ecosystems.
Residual force enhancement in myofibrils and sarcomeres
Authors: Joumaa V , Leonard T.R , Herzog W
Published: March 2008

Residual force enhancement has been observed following active stretch of skeletal muscles and single fibres. However, there has been intense debate whether force enhancement is a sarcomeric property, or is associated with sarcomere length instability and the associated development of non-uniformities. Here, we studied force enhancement for the first time in isolated myofibrils (n=18) that, owing to the strict in series arrangement, allowed for evaluation of this property in individual sarcomeres (n=79). We found consistent force enhancement following stretch in all myofibrils and each sarcomere, and forces in the enhanced state typically exceeded the isometric forces on the plateau of the force–length relationship. Measurements were made on the plateau and the descending limb of the force–length relationship and revealed gross sarcomere length non-uniformities prior to and following active myofibril stretching, but in contrast to previous accounts, revealed that sarcomere lengths were perfectly stable under these experimental conditions. We conclude that force enhancement is a sarcomeric property that does not depend on sarcomere length instability, that force enhancement varies greatly for different sarcomeres within the same myofibril and that sarcomeres with vastly different amounts of actin–myosin overlap produce the same isometric steady-state forces. This last finding was not explained by differences in the amount of contractile proteins within sarcomeres, vastly different passive properties of individual sarcomeres or (half-) sarcomere length instabilities, suggesting that the basic mechanical properties of muscles, such as force enhancement, force depression and creep, which have traditionally been associated with sarcomere instabilities and the corresponding dynamic redistribution of sarcomere lengths, are not caused by such instabilities, but rather seem to be inherent properties of the mechanisms of contraction.
The influence of surface adsorption on microbubble dynamics
Authors: Stride E
Published: March 2008

In a pure liquid, the behaviour of a gas or vapour microbubble is determined primarily by its size, the ambient pressure and the properties of the surrounding liquid. In practice, however, adsorption of a dissolved substance from the surrounding liquid onto the microbubble surface will often take place, producing a thin coating which can significantly affect both the microbubble's stability and its dynamic response. This can have important implications in a wide range of applications, including underwater acoustics, cavitation detection, medical imaging and drug delivery. The aim of this paper is to review the existing theoretical treatments of coated microbubbles and to present and discuss some recent developments. It will be shown that the presence of the coating can substantially modify the amplitude of microbubble volumetric oscillation, resonance characteristics and relative amplitude in tension and compression. Finally, the need for improved understanding of the dynamic behaviour of surface coatings at high frequencies will be discussed.
The role of feedback in microfluidic flow-focusing devices
Authors: Sullivan Matthew T , Stone Howard A
Published: March 2008

A model was developed for the analysis of steady and unsteady bubble generation frequencies in a microfluidic flow-focusing device. In both cases, the generation frequency depends on the downstream influence of bubbles created by the flow-focusing device, which provides a source of feedback. For steady-state generation of bubbles, this feedback explains the relationships among frequency, gas pressure and liquid flow rate in our experiments as well as gives a physical explanation for previously observed frequency relations. The role of feedback is also exploited to explain unsteady behaviour; we develop a numerical model and analytical expressions that agree with experimental measurements.
A mixed contact model for an immersed collision between two solid surfaces
Authors: Yang Fu-Ling , Hunt Melany L
Published: March 2008

Experimental evidence shows that the presence of an ambient liquid can greatly modify the collision process between two solid surfaces. Interactions between the solid surfaces and the surrounding liquid result in energy dissipation at the particle level, which leads to solid–liquid mixture rheology deviating from dry granular flow behaviour. The present work investigates how the surrounding liquid modifies the impact and rebound of solid spheres. Existing collision models use elastohydrodynamic lubrication (EHL) theory to address the surface deformation under the developing lubrication pressure, thereby coupling the motion of the liquid and solid. With EHL theory, idealized smooth particles are made to rebound from a lubrication film. Modified EHL models, however, allow particles to rebound from mutual contacts of surface asperities, assuming negligible liquid effects. In this work, a new contact mechanism, ‘mixed contact’, is formulated, which considers the interplay between the asperities and the interstitial liquid as part of a hybrid rebound scheme. A recovery factor is further proposed to characterize the additional energy loss due to asperity–liquid interactions. The resulting collision model is evaluated through comparisons with experimental data, exhibiting a better performance than the existing models. In addition to the three non-dimensional numbers that result from the EHL analysis—the wet coefficient of restitution, the particle Stokes number and the elasticity parameter—a fourth parameter is introduced to correlate particle impact momentum to the EHL deformation impulse. This generalized collision model covers a wide range of impact conditions and could be employed in numerical codes to simulate the bulk motion of solid particles with non-negligible liquid effects.
Reproductive parameters vary with social and ecological factors in the polygynous antFormica exsecta
Authors: Kümmerli Rolf , Keller Laurent
Published: March 2008

Due to their haplo‐diploid sex determination system and the resulting conflict over optimal sex allocation between queens and workers, social Hymenoptera have become important model species to study variation in sex allocation. While many studies indeed reported sex allocation to be affected by social factors such as colony kin structure or queen number, others, however, found that sex allocation was impacted by ecological factors such as food availability. In this paper, we present one of the rare studies that simultaneously investigated the effects of social and ecological factors on social insect nest reproductive parameters (sex and reproductive allocation, nest productivity) across several years. We found that the sex ratio was extremely male biased in a polygynous (multiple queens per nest) population of the antFormica exsecta. Nest‐level sex allocation followed the pattern predicted by the queen‐replenishment hypothesis, which holds that gynes (new queens) should only be produced and recruited in nests with low queen number (i.e. reduced local resource competition) to ensure nest survival. Accordingly, queen number (social factor) was the main determinant on whether a nest produced gynes or males. However, ecological factors had a large impact on nest productivity and therefore on a nest's resource pool, which determines the degree of local resource competition among co‐breeding queens and at what threshold in queen number nests should switch from male to gyne production. Additionally, our genetic data revealed that gynes are recruited back to their parental nests after mating. However, our genetic data are also consistent with some adult queens dispersing on foot from nests where they were produced to nests that never produced queens. As worker production is reduced in gyne‐producing nests, queen migration might be offset by workers moving in the other direction, leading to a nest network characterized by reproductive division of labour. Altogether our study shows that both, social and ecological factors can influence long‐term nest reproductive strategies in insect societies.
Ectoparasite intensities are correlated with endoparasite infection loads in willow ptarmigan
Authors: Holmstad Per R. , Jensen Knut H. , Skorping Arne
Published: March 2008

Most studies exploring the effect of parasites on host fitness traits deal with a small subset of the parasite community, or with a single parasite species. The results of such studies may be difficult to interpret, because the potential effects of other parasites are not controlled for. If intensities of different parasite species tend to covary, any demonstrated effect by one parasite species could be caused by another, covarying species. In the current study we found that intensities of two different feather lice on willow ptarmigan were positively correlated. Moreover, ectoparasite intensities could be reliably predicted by endoparasite loads. This is unexpected since feather lice are controlled by preening, while endoparasites are kept in check by the immune system. Our results suggest a link between these two aspects of parasite defense, possibly mediated by endoparasite infections reducing host energy available for preening.
Many eyes or many ewes: vigilance tactics in female bighorn sheep Ovis canadensis vary according to reproductive status
Authors: Rieucau Guillaume , Martin Julien G. A.
Published: March 2008

In gregarious animals, there is usually a negative relationship between individual vigilance and group size. This effect of group size is generally explained by increasing probability of predator detection (the many‐eyes hypothesis) and by the dilution of risk occurring in larger groups. Few studies have attempted to examine the specific implications of either hypothesis on the expected vigilance pattern of an animal. Here we examine whether reproductive status affects vigilance patterns in bighorn sheep Ovis canadensis ewes. We also test whether the observed vigilance patterns are consistent with predictions from dilution or detection models of vigilance. Although vigilance decreased with increasing group size, vigilance tactics differed between barren and lactating females. Lactating ewes relied solely on predator detection. In contrast, barren ewes benefited from both detection and dilution effects when group size increased and adjusted vigilance effort according to the proportion of lactating ewes in their group. It is generally assumed that gregariousness increases safety. Here we further show that reproductive status influenced how animals reduce predation risk and that some individuals take advantage of the vigilance effort provided by others.
Changing vulnerability to predation related to season and sex in an African ungulate assemblage
Authors: Owen‐Smith Norman
Published: March 2008

The consequences of predation for prey population dynamics depend on the extent to which this mortality is predisposed by malnutrition or senescence, or additive in the sense that animals that would otherwise not have died at that time were killed. In places lacking effective predators, few adult ungulates die during the summer or wet season months when food is plentifully available. Hence the seasonal distribution of predator kills as well as the age and sex classes of the prey indicates the extent to which malnutrition contributes to mortality as well as other influences on vulnerability. Using records of animal deaths assembled over 35 years in South Africa's Kruger National Park, these patterns were investigated for 12 ungulate species forming the prey of lions, and for three other large predators with respect to one prey species. Buffalo, kudu and giraffe were more strongly represented in kills made during the late dry season, while wildebeest and zebra made relatively greater contributions during the wet season. Impala, waterbuck, warthog and rarer antelope species became more prominent in kills during transitional periods between seasons. Five prey species showed an elevation in representation of males in lion kills during the mating season, as well as impala for all predator species. Females were more prominently represented in kills during the time of late gestation and parturition for three prey species. Hence reproductive activities as well as changing vegetation cover and food resources affected vulnerability to predation. Shifts in susceptibility to predation over the seasonal cycle corresponded with rainfall‐related variation in the annual representation of these ungulate species in lion kills. The availability of vulnerable prey species, age and sex classes at different stages of the seasonal cycle helps maintain a high abundance of lions. These factors contribute to the strong additive impact that predation has had on the abundance of some of these ungulate populations.
Fish and dragonfly nymph predators induce opposite shifts in color and morphology of tadpoles
Authors: Touchon J. C. , Warkentin K. M.
Published: March 2008

Many prey species, including amphibian larvae, can adaptively alter coloration and morphology to become more or less conspicuous to predators. Despite abundant research on predator‐induced plasticity in tadpoles, the combination of color and morphological responses to predators remains largely unexplored. We measured predator‐induced morphological and color plasticity in tadpoles. We reared tadpoles of the neotropical treefrogDendropsophus ebraccatuswith dragonfly nymph or fish predators, or in a predator‐free control. After 10 days, we digitally photographed tadpoles and measured eight morphometric variables and five tail color variables. Tadpoles reared with nymphs developed the largest and reddest tails, but incurred a developmental cost, being the smallest overall. Cues from fish induced an opposite tail phenotype in tadpoles, causing shallow achromatic tails. Control tadpoles developed intermediate tail phenotypes. This provides the first experimental evidence that tadpoles can shift both color and morphology in opposite, predator‐specific directions in response to a fish and an odonate predator. Despite mean differences, however, there was substantial variation in the degree of phenotype induction across treatments. Tail redness was correlated with tail spot size, but not perfectly, indicating that color and morphology may be partially decoupled inD. ebraccatus. Balancing selection from multiple conflicting predators may result in genetic variation for developmental plasticity.
Subsidy from the detrital food web, but not microhabitat complexity, affects the role of generalist predators in an aboveground herbivore food web
Authors: Birkhofer Klaus , Wise David H. , Scheu Stefan
Published: March 2008

The activity and density of generalist predators, such as carabid beetles, rove beetles and spiders, may increase in response to: (1) increased availability of prey from the belowground subsystem and/or (2) enhanced complexity of aboveground vegetation. Organic farming practices support decomposer populations and enhance habitat complexity due to an increased weed density. A response by generalist predators to such below‐ or aboveground changes could affect predation rates on herbivores in the aboveground food web. We tested this hypothesis in a replicated field experiment conducted in a winter wheat field, where increased predator activity could lead to improved control of herbivorous pests. In a crossed design, we increased and lowered densities of decomposer prey, and manipulated vegetation complexity using artificial plants in order to examine the effect of structural complexity in isolation from effects of plant‐attracted additional prey. Isotomid Collembola exhibited lowest activity‐densities (AD) in plots treated with soil insecticide and had gradually increasing AD in untreated plots and plots receiving detrital subsidies. Carabid beetles and cursorial spiders did not respond to increased availability of isotomid prey, and they unexpectedly displayed higher AD in the structurally less‐complex plots. Aphid density mirrored the positive response of isotomids to detrital subsidies, suggesting that aphids benefited from reduced predation due to predators switching to abundant prey in the decomposer subsystem. The absence of a numerical response by surface‐active predators apparently strengthened this indirect effect of isotomids on aphids. Our results suggest that indirect predator‐mediated prey‐prey interactions can reduce beneficial effects of detrital subsidies on pest suppression. We further demonstrated that generalist predators may not per se benefit from structural complexity. Both results document the challenges associated with management practices that support generalist predators, as these measures may not necessarily improve herbivore suppression.
Recruitment processes in long‐lived species with delayed maturity: estimating key demographic parameters
Authors: Jenouvrier Stéphanie , Tavecchia Giacomo , Thibault Jean‐Claude , Choquet Rémi , Bretagnolle Vincent
Published: March 2008

Long‐lived species show delayed maturity and generally skip breeding sites on a given year, causing difficulties in estimating demographic parameters. A novel multi‐state capture – recapture model (model G for general) is proposed to estimate survival and recruitment. Model G considers long and short periods of non‐attendance at the breeding site. Model G is compared against a reduced model (model R) to test if pre‐breeders skip the studied site a given year, potentially prospecting other breeding habitats.

This model is applied to the vulnerable Cory's shearwaters seabird species. As for many species, natal philopatry, pre‐breeding attendance and prospecting play an important role for recruitment into the breeding population. Model G shows that all Cory's shearwaters come back to their natal colony, and attend the colony before recruiting into the breeding population. Moreover, model G is preferred against model R, highlighting that prospecting plays a potentially role in the recruitment processes. Return and recruitment probabilities show similar time variation, suggesting an environmental forcing. The maximum probability of the first breeding is reached at the age of seven years. During the first year the annual survival rate is 0.52 (IC95%=[0.40, 0.64]) and pre‐breeders and adult annual survival rates do not differ, being respectively 0.88, IC95%=[0.83, 0.92] and 0.89, IC95%=[0.88, 0.9].

Model G provides an improvement to estimate demographic parameters for long‐lived species life cycle and an adequate framework to test the influence of covariates. Model G is structured by age and breeding status categories, allowing easy further population models.
Stroma‐forming endophyteEpichloë glyceriaeprovides wound‐inducible herbivore resistance to its grass host
Authors: Gonthier David J. , Sullivan Terrence J. , Brown Kenneth L. , Wurtzel Benjamin , Lawal Rasheed , VandenOever Kenny , Buchan Zachary , Bultman Thomas L.
Published: March 2008

Fungal endophyte‐grass associations are diverse and complex. Some endophytes (e.g.Neotyphodiumspp.) reproduce asexually by growing vegetatively into host seeds and many of these vertically‐transmitted endophytes form mutualisms with their hosts by providing high levels of alkaloids, such as lolines, that reduce herbivore performance. Additionally,Neotyphodium coenophialumprovides wound‐inducible herbivore resistance through increased production of lolines.Neotyphodiumlikely evolved fromEpichloëspp. which are sexually reproducing endophytes that are transmitted horizontally to the next host generation through production of stromata (fruiting bodies), which sterilize host grasses. We asked if wound‐inducible resistance like that inN.coenophialumalso occurs in the ancestral, sexually reproducingEpichloëglyceriae, which infectsGlyceria striata. Host grasses were damaged by fall armyworm caterpillars, artificially cut, or left undamaged. An aphid bioassay tested the plant's toxicity to herbivores, expression oflolc(a gene in the loline biosynthesis pathway) was quantified using real‐time RT‐PCR, and loline concentration was quantified using gas chromatography and mass spectrometry. Artificially‐damaged plants supported fewer live aphids, had greaterlolcmRNA expression, and greater loline concentration than undamaged plants. Herbivore‐damaged plants supported intermediate performance by aphids, lowlolcmRNA expression, and minimal loline concentration. Our study is the first to demonstrate sexual endophytes can produce lolines following wounding. This suggests wound‐induced responses are ancestral within theEpichloë/Neotyphodiumclade and reveals a trait of grass endophytes that may have predisposed them for the evolution of defensive mutualisms with their hosts.
Can seed‐eating birds exert top‐down effects on grasses of the Monte desert?
Authors: Marone Luis , Lopez de Casenave Javier , Milesi Fernando A. , Cueto Víctor R.
Published: March 2008

Granivorous animals can exert major effects on the abundance and diversity of plants when they are selective as well as efficient consumers. However, even under such conditions granivore impact will ultimately depend on whether environmental stress obscures plant‐animal interactions. We studied diet and seed selection patterns of seed‐eating birds to corroborate whether they are selective consumers in the central Monte desert of Argentina. Overall, 83% of seeds in bird stomachs were grass seeds, whereas only 30% of available seeds were from grass species. Therefore, we conclude that avian granivory is highly selective. We developed a set of a priori expectations to test whether birds are efficient consumers (i.e. whether they reduce seed reserves significantly), through short‐term mechanism‐explicit enclosure experiments. Birds decreased the number of selected grass seeds by >50%, and also reduced the amount of non‐selected grasses and selected forbs when selected grass seeds were scarce in the habitat. Thus, consumption was context‐dependent, varying with the composition of background seed reserves. The corroboration of foraging plasticity through mechanism‐explicit trials seems to be crucial to correctly assign direct and indirect effects of seed predation in long‐term enclosure experiments. The comparison of average grass seed reduction caused by bird predation with mean declines of grass seedlings caused by senescence (ca 95%) allowed us assess top‐down (e.g. seed availability) vs bottom‐up control (e.g. rainfall) on grass recruitment. Despite moderate to high seed predation, the number of grass seeds that remains in the soil in spring would not limit seed germination and seedling recruitment. By contrast, safe‐site availability and drought may be important factors limiting grass recruitment, at least in the undisturbed habitats of the Biosphere Reserve of Ñacuñán.
Above and below ground impacts of terrestrial mammals and birds in a tropical forest
Authors: Dunham Amy E.
Published: March 2008

Understanding the impact of losing trophic diversity has global significance for managing ecosystems as well as important theoretical implications for community and ecosystem ecology. In several tropical forest ecosystems, habitat fragmentation has resulted in declines and local extinctions of mammalian and avian terrestrial insectivores. To assess the ability of a tropical rainforest community in Ivory Coast to resist perturbation from such loss of trophic diversity, I traced feedbacks in above and below ground communities and measured changes in nutrient levels and herbivory rates in response to an experimental exclosure of avian and mammalian terrestrial insectivores. I present evidence that loss of this functional group may result in increased tree seedling herbivory and altered nutrient regimes through changes in the abundance and guild structure of invertebrates. Exclusion of top predators of the forest floor resulted in increased seedling herbivory rates and macro‐invertebrate (>5 mm) densities with strongest effects on herbivorous taxa, spiders and earthworms. Densities of microbivores including Collembola, Acarina and Sciaridae showed the opposite trend as did levels of inorganic phosphorus in the soil. Results were evaluated using path analysis which supported the presence of a top down trophic cascade in the detrital web which ultimately affected turnover of phosphorus, a limiting nutrient in tropical soils. Results illustrate the potential importance of vertebrate predators in both above and belowground food webs despite the biotic diversity and structural heterogeneity of the rainforest floor.
A possible role of social activity to explain differences in publication output among ecologists
Authors: Grim Tomáš
Published: March 2008

Publication output is the standard by which scientific productivity is evaluated. Despite a plethora of papers on the issue of publication and citation biases, no study has so far considered a possible effect of social activities on publication output. One of the most frequent social activities in the world is drinking alcohol. In Europe, most alcohol is consumed as beer and, based on well known negative effects of alcohol consumption on cognitive performance, I predicted negative correlations between beer consumption and several measures of scientific performance. Using a survey from the Czech Republic, that has the highest per capita beer consumption rate in the world, I show that increasing per capita beer consumption is associated with lower numbers of papers, total citations, and citations per paper (a surrogate measure of paper quality). In addition I found the same predicted trends in comparison of two separate geographic areas within the Czech Republic that are also known to differ in beer consumption rates. These correlations are consistent with the possibility that leisure time social activities might influence the quality and quantity of scientific work and may be potential sources of publication and citation biases.
Determinants of Auditor Choice: Evidence from a Small Client Market
Authors: Knechel W. Robert , Niemi Lasse , Sundgren Stefan
Published: March 2008

This paper analyzes the auditor choices for a sample of 2,333 predominantly small and mid‐sized Finnish firms. Finland requires virtually all commercial enterprises to have a financial statement audit, but allows the smallest firms to choose from four types of audit firms: first tier international firms, first tier national firms, second tier local auditors and non‐certified auditors. We find that among the smallest firms, the choice to hire a certified auditor relates to the level of complexity in the organization as measured by size and extent of workforce. For firms that must use a certified auditor, we find that the choice between a first tier and second tier firm is related to size, the extent of debt financing, and complexity associated with being a member of an associated group. Finally, in the upper end of the market, the decision to hire a large international firm relates to size, the need for financing, be it equity or debt, and complexity due to a broad labour force. This pattern is interesting because it indicates that the need for a higher quality auditor is driven first by complexity, then as the firm grows, it is supplemented by the use of debt financing and ultimately by the need to raise equity as well as debt financing.
Studies on diarrheagenic Escherichia coli isolated from children with diarrhea in Myanmar
Authors: Takahashi Eizo , Sultan Zafar , Shimada Sumika , Aung Wah Wah , Nyein Mar Mar , Oo Khin Nwe , Nair Gopinath Balakrish , Takeda Yoshifumi , Okamoto Keinosuke
Published: March 2008

Escherichia coli isolates from 217 children in Myanmar with diarrhea were investigated for the presence of virulence genes related to diarrhea by colony hybridization and PCR. The genes examined were lt, stI, stII, stx1, stx2, eae, bfp, pCVD (which is the representative gene of plasmid of pCVD of EAEC), and ial (which is invasion‐associated locus of the invasion plasmid found in EIEC). Isolates from 47 of 217 children (21.7%) possessed virulence genes characteristic of diarrheagenic E. coli. No instance was found of co‐existence of different E. coli strains with different virulence genes in the same patient. Diarrheagenic E. coli are currently classified into five categories based on their virulence markers: ETEC, EHEC, EPEC, EAEC, and EIEC. Of the 47 isolates examined, 30 were EAEC, 12 were EPEC and 5 were ETEC. Susceptibility tests for antimicrobial agents showed that almost all diarrheagenic isolates were resistant to penicillin, tetracycline and streptomycin. However, the majority of strains were sensitive to cephalexin, nalidixic acid and norfloxacin. In particular, 42 of the 47 isolates were sensitive to norfloxacin, which is a fluoroquinolone. This study shows EAEC and EPEC are responsible for sporadic diarrhea in Myanmar and fluoroquinolones appear to be effective in the treatment of these patients.
Catalase gene disruptant of the human pathogenic yeast Candida albicans is defective in hyphal growth, and a catalase‐specific inhibitor can suppress hyphal growth of wild‐type cells
Authors: Nakagawa Yoshiyuki
Published: March 2008

Although the catalase gene (CAT1) disruptant of the human pathogenic yeast Candida albicans was viable under ordinary growth conditions, we previously found that it could not grow on YPD (yeast extract/peptone/dextrose) containing SDS or at higher growth temperatures. To investigate the pleiotrophic nature of the disruptant, we examined the effect of the catalase inhibitor 3‐AT on the growth of wild‐type strains. Surprisingly, the addition of 3‐AT and SDS caused the wild‐type cells to be non‐viable on YPD plates. We found an additional phenotype of the catalase gene disruptant: it did not produce normal hyphae on Spider medium. Hyphal growth was observed in a CAP1 (Candida AP‐1‐like protein gene) disruptant, a HOG1 (high‐osmolarity glycerol signaling pathway gene) disruptant, and the double CAP1/HOG1 disruptant, suggesting that the defect in hyphal formation by the catalase disruptant was independent of these genes. Addition of 3‐AT and SDS to hyphae‐inducing media suppressed growth of normal hyphae in the wild‐type strain. The potential necessity for catalase action upon exposure to hyphae‐inducing conditions was confirmed by the immediate elevation of the catalase gene message. In spite of the requirement for catalase during hyphal growth, the catalase gene disruptant was capable of forming germ tubes in medium containing serum.
Distinct immunohistochemical localization in Kuru plaques using novel anti‐prion protein antibodies
Authors: Hosokawa Tomoko , Ono Fumiko , Tsuchiya Kotaro , Sato Ichiro , Takeyama Natsumi , Ueda Susumu , Zanusso Gianluigi , Takahashi Hidehiro , Sata Tetsutaro , Sakudo Akikazu , Suguira Katsuaki , Baj Andreina , Toniolo Antonio , Yoshikawa Yasuhiro , Onodera Takashi
Published: March 2008

By immunizing Prnp‐knockout mice with synthetic polypeptides, a panel of mAbs directed to bovine PrPC was obtained. The mAb panel was characterized by the ELISA method, where synthetic polypeptides were used for epitope mapping. Different reactivity patterns were identified. The ability of these mAbs to detect abnormal PrPSc in CJD cases was studied by immunohistochemistry. All mAbs were tested for PrPSc in murine, bovine, monkey and human brain tissues. Three mAbs recognized the fragmented PrP epitope in our ELISA. Antibody 1D12 was strongly reactive to ovine and squirrel monkey tissues infected with a scrapie agent, although non‐reactive to scrapie‐infected mouse tissues. Antibody 2D8 was clearly reactive to type‐2 but not type‐1 CJD human tissues. Of particular interest was the reactivity of mAb 6C4 with the inner structure of Kuru plaques (peripheral pattern) in a type‐2 CJD case and mAb T2, 1D12, 2B11, 2D8, 4B5 and 6G3‐2 with the central area (central pattern). The fact that different anti‐PrP mAbs possess distinct staining properties suggests that the PrPc to PrPSc conversion might involve a multiple‐step process.
Analysis of splenic Gr‐1int immature myeloid cells in tumor‐bearing mice
Authors: Yamamoto Yoshiko , Ishigaki Hirohito , Ishida Hideaki , Itoh Yasushi , Noda Yoichi , Ogasawara Kazumasa
Published: March 2008

It is known that the number of ImC, expressing myeloid markers, CD11b and Gr‐1, increase with tumor growth and ImC play a role in the escape of tumor cells from immunosurveillance in tumor‐bearing mice and cancer patients. However, the mechanisms by which ImC suppress immune responses in tumor‐bearing mice have not been completely elucidated. In the present study, we investigated the function of splenic ImC freshly isolated from tumor‐bearing mice and splenic ImC differentiated in vitro by GM‐CSF. Freshly isolated splenic ImC were divided into two groups depending on Gr‐1 expression, Gr‐1 high (Gr‐1hi) and intermediate (Gr‐1int). Freshly isolated splenic Gr‐1int ImC, but not Gr‐1hi ImC, from tumor‐bearing mice reduced production of IFN‐γ in CD8+ T cells, but neither splenic Gr‐1int ImC nor Gr‐1hi ImC isolated from naive mice did. Both Gr‐1int and Gr‐1hi ImC differentiated in vitro by GM‐CSF inhibited production of IFN‐γ in both CD8+ and CD4+ T cells. In addition, the differentiated Gr‐1int ImC, one‐third of which were CD11c+F4/80+ cells, and their culture supernatants suppressed proliferative responses of T cells stimulated by CD3 ligation, but the differentiated Gr‐1hi ImC and their culture supernatants did not. These results suggest that Gr‐1int ImC are altered to immune‐suppressive cells in tumor circumstances and that they are differentiated by GM‐CSF progressively into CD11c+F4/80+ cells with further suppressive activity against T cells.
A chromosomal duplication that includes the canine microsatellite INRA21 in Labrador Retrievers
Authors: Onogi A. , Nurimoto M. , Sato Y. , Morita M.
Published: March 2008

INRA21 is one of the canine microsatellites recommended for parentage verification by the International Society for Animal Genetics. In Labrador Retrievers, abnormal peak patterns such as three‐peak patterns during capillary electrophoresis were frequently observed at INRA21. Pedigree analysis indicated that the abnormal peak patterns were due to inheritable causes, and semiquantitative multiplex (SQM) PCR analysis showed that the abnormal peak patterns were caused by chromosomal duplication. Walking SQM‐PCR analysis revealed that the size of the duplicated segment was approximately 1.58 Mb. Genotypes of microsatellites within the duplicated segment indicated that the duplication was an identical‐by‐descent mutation. This duplication is probably carried by more than half of the dogs in the Japanese population of Labrador Retrievers. The abnormal peak patterns at INRA21 were also observed in German Shorthaired Pointers and Flat‐Coated Retrievers. Genotyping analysis of the microsatellites within the duplicated segment in Labrador Retrievers suggested that the abnormal peak patterns observed in the two breeds were due to the duplication inherited from the same ancestor as the duplication of Labrador Retrievers. This study urges attention to the use of INRA21 and shows an example of copy number polymorphisms that are characteristic to dog breeds or lineages.
IVE (ifosfamide, epirubicin and etoposide) is a more effective stem cell mobilisation regimen than ICE (ifosphamide, carboplatin and etoposide) in the context of salvage therapy for lymphoma
Authors: Fox C. P. , McMillan A. K. , Bishton M. J. , Haynes A. P. , Russell N. H.
Published: March 2008

Two commonly used chemotherapy regimens for lymphoma salvage therapy were compared: ICE (ifosphamide, carboplatin and etoposide) ± rituximab and IVE (ifosfamide, epirubicin and etoposide) ± rituximab, for their efficacy in mobilising peripheral blood stem cells for autologous transplantation. Significant differences were observed between the cohorts in terms of number of patients mobilising the stipulated minimum >2 × 106 CD34+/kg (99·2% in IVE group versus 83% in ICE group: P = 0·0002) and also in terms of the number of patients achieving the predetermined target of >5 × 106 CD34+/kg, both in total and during the first apheresis procedure (72% in IVE versus 51% in ICE group and 49% in IVE versus 7% in ICE group: P = 0·02 and P < 0·0001 respectively). This analysis of two similar groups of patients treated within a single‐centre appears to demonstrate that the IVE regimen is a more effective stem cell mobilisation regimen than ICE in the context of salvage therapy for Hodgkin and non‐Hodgkin lymphoma, allowing more patients to achieve the target CD34+ cell collection and proceed to high‐dose therapy and autologous stem cell transplantation.
The story of the discovery of heparin and warfarin
Authors: Wardrop Douglas , Keeling David
Published: March 2008

Heparin and coumarins have been the mainstay of anticoagulant therapy throughout our working lives. As we stand on the threshold of a new era of anticoagulants it is timely to look back upon their discovery and development. Both have fascinating stories to tell. Jay McLean claimed to have discovered heparin whilst a medical student, although this is disputed. The story of warfarin leads us from a mysterious haemorrhagic disease of cattle to the development of a rat poison which became one of the most commonly prescribed drugs in history. Many people were involved in both stories and we owe them all a debt of gratitude.
Influence of iron chelators on myocardial iron and cardiac function in transfusion‐dependent thalassaemia: a systematic review and meta‐analysis
Authors: Mamtani Manju , Kulkarni Hemant
Published: March 2008

Iron chelators have dramatically prolonged the life expectancy of patients with transfusion‐dependent thalassaemia, but their precise clinical benefit in reducing the myocardial iron burden and improving cardiac function is unknown. This systematic review and meta‐analysis included published clinical trials that assessed the efficacy of iron chelators in regularly transfused patients of thalassaemia major for two commonly reported outcomes – myocardial iron content and left ventricular ejection fraction (LVEF). The meta‐analysis of 392 patients for myocardial iron content and 291 patients for LVEF showed that (i) iron chelators reduced cardiac iron content by 23·9% (95% confidence interval 17·3–29·8%); (ii) there was no significant difference between the amount of iron reduced by deferoxamine and deferiprone (P = 0·9504); and (iii) LVEF was not significantly influenced by iron chelators – summary Hedge’s g 0·13 (95% confidence interval −0·10–0·36). A significant publication bias existed for LVEF (Egger’s P = 0·049) but not for myocardial iron (Egger’s P = 0·871). Our results indicate that iron chelators significantly reduce myocardial iron content. Further, the choice of deferoxamine versus deferiprone may rest on factors other than their efficacy to reduce cardiac iron load.
PROLACTIN LEVELS AND PITUITARY ENLARGEMENT IN HORMONE‐TREATED MALE‐TO‐FEMALE TRANSSEXUALS
Authors: ASSCHEMAN H. , GOOREN L. J. G. , ASSIES J. , SMITS J. P. H. , DE SLEGTE R.
Published: March 2008

PRL levels were evaluated during long‐term treatment with cyproterone acetate 100 mg and ethinyloestradiol 100 μg/day orally or depot‐oestrogens in 214 male‐to‐female transsexuals. PRL levels increased above normal in all subjects (normal < 300 mU/l). In 46 (21.4%) subjects PRL levels rose to > 1000 mU/l. The incidence of PRL levels > 1000 mU/l was 3.7–7.2% per treatment year. Grossly elevated PRL levels were associated with high doses of oestrogens (P < 0.05) and advanced age at the start of treatment (P < 0.05). In 23 subjects PRL levels > 1000 mU/l decreased by more than 50% spontaneously (n= 5) or after dose reduction (n= 18). In five of the subgroup of 15 subjects with persistent PRL levels > 1000 mU/l enlargement of the pituitary gland was shown by CT‐scanning. These data suggest that the lowest possible oestrogen dose and lifelong follow‐up of hormone‐treated male‐to‐female transsexuals is essential.
IMMUNOGENETICS OF GRAVES' OPHTHALMOPATHY
Authors: WEETMAN A. P. , SO A. K. , WARNER C. A. , FORONI L. , FELLS P. , SHINE B.
Published: March 2008

We have performed an immunogenetic analysis of 53 patients with severe Graves' ophthalmopathy, 51 patients with Graves' disease but little or no clinically apparent eye disease, and 90 controls. The distribution of restriction fragment length polymorphisms was analysed in the three groups, using probes for the HLA‐DQα and DRβ regions, the T‐cell receptor Cx, Kx, Cβ and Jγ genes and the immunoglobulin gene switch regions, Sx and Sμ. There was no abnormal distribution of these polymorphisms in either group of Graves' patients, or differences between the Graves' patients with or without eye disease. It was possible to assign HLA‐DR types in most patients using the polymorphisms found after probing with DQα and DRβ; there was no abnormal distribution of DR types (including HLA‐DR3) assigned by restriction fragment polymorphisms in the two Graves' groups. These results fail to confirm the reported associations between ophthalmopathy and HLA‐DR3 and between Graves' disease and the T‐cell receptor Cβ polymorphism; they also argue against a strong influence of Gm allotypes in Graves' disease since these genes are in linkage disequilibrium with the Sα polymorphisms. The association of Graves' disease with HLA‐DR3, defined hitherto using serological reagents, may be less strong than previously described.
OSMOREGULATION OF VASOPRESSIN SECRETION AND THIRST IN CYCLICAL OEDEMA
Authors: THOMPSON C. J. , BURD J. M. , BAYLIS P. H.
Published: March 2008

Osmoregulation of vasopressin release and thirst was studied in the mid‐follicular and mid‐luteal phases of the menstrual cycle of five patients with cyclical oedema defined by peripheral oedema and weight gain (> 30 kg) manifest in two consecutive luteal phases. Results are compared to those already obtained in eight healthy women. In the patients, basal plasma osmolality in the mid‐luteal phase was significantly lower than in the mid‐follicular periods (patients, 283 ± 1, 287 ± 1 mOsmol/kg, respectively, mean ± SEM, P < 0.05; controls, 282 ± 1, 286 ± 1 mOsmol/kg, respectively, P < 0.05). Plasma osmolality (pOsm) and plasma arginine vasopressin (pAVP) were measured during hypertonic (850 mmol/l) saline infusion in both phases of the cycle; linear regression analyses of these data gave the following mean regression equations, (i) mid‐follicular, pAVP=0.55 (pOsm — 285), r=0.94 and (ii) mid‐luteal, pAVP=0.42 (pOsm —281), r=0.93. The abscissal intercept was significantly different (P < 0.025). Osmotic threshold for severe thirst onset was lower in the mid‐luteal phase compared to the mid‐follicular value (296 ± 1, 299 ± 1 mOsmol/kg, respectively, P < 0.01). Basal data and results of thirst onset and theoretical threshold for vasopressin release in response to osmotic stimulation obtained in the patients were similar to healthy control women. We conclude that osmoregulation in cyclical oedema is normal.
HETEROZYGOTES FOR 17α‐HYDROXYLASE DEFICIENCY CAN BE DETECTED WITH A SHORT ACTH TEST
Authors: WIT J. M. , VAN ROERMUND H. P. C. , OOSTDIJK W. , BENRAAD T.H. J. , THIJSSEN J. H. H. , BOER P. , JANSEN M. , SPIT M. , VAN DEN BRANDE J. L.
Published: March 2008

A short ACTH test was performed in the six parents, and four siblings, of three cases with 17α‐hydroxylase deficiency. Baseline steroid levels were all normal in female heterozygotes but in males 17α‐hydroxyprogesterone levels were elevated. After ACTH‐stimulation, plasma levels of corticosterone were elevated in five obligate heterozygotes and 18‐hydroxydeoxycorticosterone levels were increased in four of them. Two of the four siblings had biochemical signs of heterozygosity. The short ACTH test appears to be an efficient method for detecting heterozygosity, but the abnormalities found are more heterogeneous than previously suggested.
Difficulties in diagnosing small round cell tumours of childhood from fine needle aspiration cytology samples
Authors: Pohar‐Marinšek Živa
Published: March 2008

There are four basic reasons for the difficulties in diagnosing small round cell tumours (SRCT) in childhood from fine needle aspiration cytology (FNAC) samples. First, SRCTs are rare and it is difficult for cytopathologists to obtain enough experience for rendering reliable diagnoses. Second, SRCTs are morphologically very similar. Third, many SRCTs do not have specific antigens which could be demonstrated with immunocytochemistry (ICC) or they lose them when poorly differentiated. In addition, cross reactivity exists between some SRCTs. Unstandardized performance of ICC also contributes to the difficulties due to unreliable results. Fourth, suboptimal FNAC samples add additional pitfalls. The latter may be due to partly degenerate samples or to unrepresentative ones in cases where a SRCT is a heterologous component of another nosological entity. Lymphoma, neuroblastoma, nephroblastoma, Ewing’s tumour/primitive neuroendocrine tumours and rhabdomyosarcoma are discussed in detail, while other less common SRCTs are mentioned as differential diagnoses when appropriate. The use of cytogenetic and molecular techniques for differentiating between certain SRCTs is helpful in some doubtful cases. However, there are still problems in the use of these techniques, especially their cost which may delay their being introduced in every cytopathology laboratory.