bluuebunny/crossref_metadata_2025_split huggingface dataset:
Type I and type II fatty acid biosynthesis inEimeria tenella: enoyl reductase activity and structure
Authors: LU J. Z. , MUENCH S. P. , ALLARY M. , CAMPBELL S. , ROBERTS C. W. , MUI E. , McLEOD R. L. , RICE D. W. , PRIGGE S. T. 
Published: August 2007

SUMMARYApicomplexan parasites of the genusEimeriaare the major causative agent of avian coccidiosis, leading to high economic losses in the poultry industry. Recent results show thatEimeria tenellaharbours an apicoplast organelle, and that a key biosynthetic enzyme, enoyl reductase, is located in this organelle. In related parasites, enoyl reductase is one component of a type II fatty acid synthase (FAS) and has proven to be an attractive target for antimicrobial compounds. We cloned and expressed the mature form ofE. tenellaenoyl reductase (EtENR) for biochemical and structural studies. Recombinant EtENR exhibits NADH-dependent enoyl reductase activity and is inhibited by triclosan with an IC50value of 60 nm. The crystal structure of EtENR reveals overall similarity with other ENR enzymes; however, the active site of EtENR is unoccupied, a state rarely observed in other ENR structures. Furthermore, the position of the central beta-sheet appears to block NADH binding and would require significant movement to allow NADH binding, a feature not previously seen in the ENR family. We analysed theE. tenellagenomic database for orthologues of well-characterized bacterial and apicomplexan FAS enzymes and identified 6 additional genes, suggesting thatE. tenellacontains a type II FAS capable of synthesizing saturated, but not unsaturated, fatty acids. Interestingly, we also identified sequences that appear to encode multifunctional type I FAS enzymes, a feature also observed inToxoplasma gondii, highlighting the similarity between these apicomplexan parasites.
Contribution to the modeling of nonsmooth multipoint contact dynamics of biped locomotion—Theory and experiments
Authors: Rodić Aleksandar , Vukobratović Miomir , Addi Khalid , Dalleau Georges 
Published: August 2007

SUMMARYThis paper suggests a generalized approach to the mathematical modeling of biped locomotion systems (humans or humanoid robots) with special attention paid to impact and contact dynamics. Instead of the usual inductive approach that starts from the analysis of different situations of real motion (walking, running, jumping, climbing the stairs, etc.) and tries to make a generalization, a deductive approach is pursued, whereby an entirely general problem is considered. Impact dynamics is modeled applying the linear complementarity problem (LCP) formulation. General methodology is explained and demonstrated via the synthesis of a spatial biped model. The validity of the modeling approach is proved by experimental measurements on a human subject in the laboratory conditions. Plenty of graphic presentations illustrating experimental results, as well as the results of the corresponding simulation tests are shown.
Modified Newton's method applied to potential field-based navigation for nonholonomic robots in dynamic environments
Authors: Ren Jing , McIsaac Kenneth A. , Patel Rajni V. 
Published: August 2007

SUMMARYThis paper is to investigate inherent oscillations problems of potential field methods (PFMs) for nonholonomic robots in dynamic environments. In prior work, we proposed a modification of Newton's method to eliminate oscillations for omnidirectional robots in static environment. In this paper, we develop control laws for nonholonomic robots in dynamic environment using modifications of Newton's method. We have validated this technique in a multi-robot search-and-forage task. We found that the use of the modifications of Newton's method, which applies anywhere C2 continuous navigation functions are defined, can greatly reduce oscillations and speed up the robot's movement, when compared to the standard gradient approaches.
Infant mortality in the Canbury area of Kingston upon Thames, 1872–1911
Authors: FRENCH CHRISTOPHER , WARREN JULIET 
Published: August 2007

ABSTRACTThis article examines aspects of infant mortality in a discrete part of Kingston upon Thames – the Canbury area – in the late nineteenth and early twentieth centuries. It highlights the concentration of infant mortality in this area, which was characterized – especially in the 1890s – by an increasingly overcrowded and unhealthy environment, made worse by the proximity of animals to living space. Animal manure attracted flies which, particularly during hot summer months, transmitted disease to infant foodstuffs, especially milk, increasing the incidence of summer diarrhoea. Poor feeding and child-care practices contributed to high levels of infant mortality, a situation acknowledged by Kingston's Medical Officer of Health.
Distance Hereditary Graphs and the Interlace Polynomial
Authors: ELLIS-MONAGHAN JOANNA A. , SARMIENTO IRASEMA 
Published: August 2007

The vertex-nullity interlace polynomial of a graph, described by Arratia, Bollobás and Sorkin in [3] as evolving from questions of DNA sequencing, and extended to a two-variable interlace polynomial by the same authors in [5], evokes many open questions. These include relations between the interlace polynomial and the Tutte polynomial and the computational complexity of the vertex-nullity interlace polynomial. Here, using the medial graph of a planar graph, we relate the one-variable vertex-nullity interlace polynomial to the classical Tutte polynomial when x=y, and conclude that, like the Tutte polynomial, it is in general #P-hard to compute. We also show a relation between the two-variable interlace polynomial and the topological Tutte polynomial of Bollobás and Riordan in [13].We define the γ invariant as the coefficient of x1in the vertex-nullity interlace polynomial, analogously to the β invariant, which is the coefficientof x1in the Tutte polynomial. We then turn to distance hereditary graphs, characterized by Bandelt and Mulder in [9] as being constructed by a sequence ofadding pendant and twin vertices, and show that graphs in this class have γ invariant of 2n+1whenntrue twins are added intheir construction. We furthermore show that bipartite distance hereditary graphs are exactly the class of graphs with γ invariant 2, just as the series-parallel graphs are exactly the class of graphs with β invariant 1. In addition, we show that a bipartite distance hereditary graph arises precisely as the circle graph of an Euler circuitin the oriented medial graph of a series-parallel graph. From this we conclude that the vertex-nullity interlace polynomial is polynomial time to compute for bipartite distancehereditary graphs, just as the Tutte polynomial is polynomial time to compute for series-parallel graphs.
A ten-year review of commercial vaccine performance for control of tick infestations on cattle
Authors: Fuente José de la , Almazán Consuelo , Canales Mario , Pérez de la Lastra José Manuel , Kocan Katherine M. , Willadsen Peter 
Published: August 2007

AbstractTicks are important ectoparasites of domestic and wild animals, and tick infestations economically impact cattle production worldwide. Control of cattle tick infestations has been primarily by application of acaricides which has resulted in selection of resistant ticks and environmental pollution. Herein we discuss data from tick vaccine application in Australia, Cuba, Mexico and other Latin American countries. Commercial tick vaccines for cattle based on theBoophilus microplusBm86 gut antigen have proven to be a feasible tick control method that offers a cost-effective, environmentally friendly alternative to the use of acaricides. Commercial tick vaccines reduced tick infestations on cattle and the intensity of acaricide usage, as well as increasing animal production and reducing transmission of some tick-borne pathogens. Although commercialization of tick vaccines has been difficult owing to previous constraints of antigen discovery, the expense of testing vaccines in cattle, and company restructuring, the success of these vaccines over the past decade has clearly demonstrated their potential as an improved method of tick control for cattle. Development of improved vaccines in the future will be greatly enhanced by new and efficient molecular technologies for antigen discovery and the urgent need for a tick control method to reduce or replace the use of acaricides, especially in regions where extensive tick resistance has occurred.
Directed exospermia: II. VUV-UV spectroscopy of specialized UV screens, including plant flavonoids, suggests using metabolic engineering to improve survival in space
Authors: Zalar Andreja , Tepfer David , Hoffmann Søren V. , Kollmann Albert , Leach Sydney 
Published: August 2007

AbstractWe used synchrotron light to determine VUV-UV absorption spectra (125–340 nm) of thin films of substances associated with UV resistance in specific groups of organisms or across limited phylogenetic boundaries: scytonemin, mycosporine-like amino acids, dipicolinic acid, β-carotene, melanin and flavonoids (quercitrin, isoquercitrin, robinin and catechin). The objective was to extend known UV absorption spectra into the vacuum UV, and to evaluate the likely effectiveness of these molecules in shielding DNA from the unfiltered solar UV found in space, using similarity with DNA absorption spectra as the primary criterion. The spectroscopy indicated that plant flavonoids would be ideal UV screens in space. We suggest that flavonoids represent primitive UV screens, and offer explanations (including horizontal gene transfer) for their presence in plants. We also discuss the possibility of improving UV resistance by increasing flavonoid accumulation through metabolic engineering, in the hope of better adapting life for space travel, i.e. for its dissemination away from the Earth (exospermia). Finally, we propose using plant seeds as exospermia vehicles for sending life (including artificial life) into space.
Two distinct mechanisms segregate Prospero in the longitudinal glia underlying the timing of interactions with axons
Authors: Griffiths Rachel C. , Benito-Sipos Jonathan , Fenton Janine C. , Torroja Laura , Hidalgo Alicia 
Published: August 2007

AbstractProspero is required in dividing longitudinal glia (LG) during axon guidance; initially to enable glial division in response to neuronal contact, and subsequently to maintain glial precursors in a quiescent state with mitotic potential. Only Prospero-positive LG respond to neuronal ablation by over-proliferating, mimicking a glial-repair response. Prospero is distributed unequally through the progeny cells of the longitudinal glioblast lineage. Just before axon contact the concentration of Prospero is higher in two of the four progeny cells, and after axon guidance Prospero is present only in six out of ten progeny LG. Here we ask how Prospero is distributed unequally in these two distinct phases. We show that before neuronal contact, longitudinal glioblasts undergo invaginating divisions, perpendicular to the ectodermal layer. Miranda is required to segregate Prospero asymmetrically up to the four glial-progeny stage. After neuronal contact, Prospero is present in only the LG that activate Notch signalling in response to Serrate provided by commissural axons, and Numb is restricted to the glia that do not contain Prospero. As a result of this dual regulation of Prospero deployment, glia are coupled to the formation and maintenance of axonal trajectories.
EOSINOPHILIA AND ACQUISITION OF RESISTANCE TO NEMATOSPIROIDES DUBIUS IN MICE SENSITIZED WITH ADULT WORMS
Authors: Hurley James C , Vadas Mathew A 
Published: August 2007

SummaryBALB/c mice develop resistance to challenge with N. dubius third stage infective larvae (L3) 2–3 weeks after the administration of N. dubius worms. In contrast, CBA/H mice fail to develop resistance. Experiments were performed to test the hyptothesis that the reason for the different behaviour of these mice was a difference in their eosinophil response. BALB/c mice and BALB/c → (BALB/c → CBA/H)F1 bone marrow chimaeras but not CBA/H mice or CBA/H → (BALB/c × CBA/H)F1 chimaeras mounted strong eosinophilia after N. dubius sensitization and the eosinophil response Was associated with resistance to L3 infection in these mice. Induction of a mild eosinophilia in CBA/H mice by non‐parasite antigen keyhole limpet haemocyanin (KLH) in complete Freund's adjuvant (CFA) following cyclophosphamide (CY) treatment was associated with the acquisition of a degree of resistance to L3 infection. In BALB/c mice, increase in eosinophilia induced by CY and KLH‐CFA was not associated with a further reduction in worm numbers. These experiments support the hypothesis that eosinophilia is an important component of host protective immunity in vivo, and suggest a new basis for the heterogeneity of the outcome of some parasite infestations.
FALLOPIAN TUBE MICROVASCULATURE IN THE RABBIT
Authors: Verco Christopher J , Ganon Brendan J , Jones Warren R 
Published: August 2007

SummaryThe microvascular architecture of rabbit Fallopian tube isthmic, ampullary and fimbrial regions was examined by the corrosion vascular cast‐scanning electron microscope method. The aorta and inferior vena cava of virgin adult female rabbits (2·5–3·5 kg) were cannulated; after blood wash out, methacrylate casting medium was infused via the aorta. After plastic hardening, Fallopian tubes were excised, tissues corroded and casts prepared for scanning electron microscopy. The isthmic myosalpinx is encircled subserosally by an interlocking venous plexus. We suggest that a rise in pelvic venous pressure could lead to a decrease in isthmic luminal diameter and thus act as a sphincter contributing to the known delay in ovum transport at the ampullary isthmic junction. Stereo pairs of photomicrographs showed that isthmic plicae are supplied by arterioles which change little in diameter passing through the tubal wall. Near the apex of a fold, these arterioles terminate in a subepithelial capillary plexus which drains to deep mucosal and plical core venules. In contrast, the ampulla is supplied by smaller and less frequent arterioles. Frequent large venules extending high into the plicae drain the subepithelial capillary plexus. Based on this microvascular architecture, we suggest that the subepithelial capillary plexus of the apical region of the plicae probably contains high pressure blood in the isthmus and lower pressure blood in the ampulla. Therefore, plicae in these regions may be specialised for net luminal fluid secretion and absorption respectively, implying a role for the microvasculature in tubal transport by initiation or modification of fluid flow along the lumen.
DETECTION OF SPECIFIC MURINE ANTI‐TUMOUR IMMUNITY AND SERUM FACTORS BY THE INDIRECT E‐ROSETTE AUGMENTATION ASSAY
Authors: Phillips RG , Halliday WJ 
Published: August 2007

SummaryThe spontaneous interaction of sheep erythrocytes and human lymphocytes results in the formation of aggregates known as E‐rosettes. The antigen reactivity of murine T‐lymphocytes can be detected indirectly by the production of a lymphokine that augments the E‐rosette‐forming ability of human lymphocytes. An indirect E‐rosette augmentation (ERA) assay was used to study cellular reactivity and tumour‐related serum reactions in mice bearing methylcholanthrene (MCA)‐induced tumours. The assay was used to demonstrate the antigenic specificity of two tumours and to detect blocking factors in tumour‐bearer serum. Blocking factors were shown to be tumour‐specific and to act on lymphocytes at an early stage before exposure to antigen.
LEISHMANIA TROPICA MAJOR IN MICE: VACCINATION AGAINST CUTANEOUS LEISHMANIASIS IN MICE OF HIGH GENETIC SUSCEPTIBILITY
Authors: Mitchell Graham F , Handman Emanuela 
Published: August 2007

SummaryBALB/c and BALB/c.H‐2b mice are genetically susceptible to development of persistent and severe disease following cutaneous injection of promastigotes of the protozoan parasite, Leishmania tropica major, whereas C57BL/6 are relatively resistant. Resistance in C57BL/6 can be further increased by intraperitoneal injection of living, but not killed, promastigotes prior to cutaneous challenge. Severely diseased BALB/c mice can show resistance to development of a second cutaneous lesion but apparently only in the advanced stages of systemic life‐threatening disease. A striking level of resistance to persistent disease has been demonstrated in BALB/c.H‐2b mice pre‐injected with frozen and thawed L. t. major‐infected macrophages of the continuous macrophage cell line IC‐21 (H‐2b) together with Corynebacterium parvum. No resistance is seen in recipients of either C. parvum or the crude antigen mixture alone. Protection is afforded by intraperitoneal and not subcutaneous injection of crude antigen plus adjuvant. In these vaccination studies all evidence points to the infected macrophage as the most appropriate source of ‘host‐protective’ antigens as well as being the most likely target of host‐protective immunity. Resistance is expressed in vaccinated mice as minimal signs of cutaneous disease and rapid resolution of any small lesions which do develop. Frozen and thawed promastigotes plus C. parvum will not induce resistance to persistent disease in BALB/c H‐2b mice and preincubation of promastigotes with sera from resistant vaccinated mice does not influence their capacity to cause cutaneous disease. The results provide baseline data for vaccination attempts in genetically susceptible hosts using isolated L. t major antigens (and, in particular, infected macrophage antigens) and highlight the utility of the intraperitoneal route of injection and the use of the therapeutic biological, C. parvum, as an adjuvant in such studies.
SALIVA AND BREAST MILK COMPOSITION DURING THE MENSTRUAL CYCLE OF WOMEN
Authors: Prosser CG , Hartmann PE 
Published: August 2007

SummaryTwo acute changes in breast milk composition occur during the ovulatory menstrual cycle of women. To determine whether these changes were peculiar to the mammary gland, the composition of unstimulated whole saliva was followed during the menstrual cycle of women. This investigation showed acute, 3–9‐fold increases in the concentration of glucose in saliva during the ovulatory menstrual cycle of lactating women. These changes were synchronous with changes in the concentrations of Na and K in breast milk. In contrast to salivary glucose, milk glucose decreased at these times. Milk glucose values were 1·3‐fold lower on these days than on the days preceding and following the decrease. Similar acute increases were observed in salivary glucose of non‐lactating women. The total duration of the changes in milk and saliva composition was 12–32 h. No cyclic changes in the concentration of glucose were observed in the saliva from women taking oral contraceptives.Since two different epithelial glands are affected simultaneously during the menstrual cycle, it is likely that a hormonal mechanism is involved. Moreover, since the acute increases in salivary glucose also occurred in non‐lactating women, we suggest that the factors causing the changes in milk composition are not just a consequence of lactation and are probably closely associated with the hormones controlling the menstrual cycle in all women.
PLASMA CLEARANCE AND DISTRIBUTION OF 125I‐OVINE PLACENTAL LACTOGEN IN SHEEP
Authors: Reddy S , Watkins WB 
Published: August 2007

SummaryThe plasma clearance of 125I‐ovine placental lactogen (125I‐oPL) in pregnant, non‐pregnant and foetal sheep followed a biphasic exponential curve. The initial half‐life (t1(½)) of the hormone ranged from 5·7–12·7 min. The molecular identity of 125I‐oPL in plasma samples was examined by gel filtration chromatography. At the end of blood sampling, the high concentrations of radioactivity in the thyroid, kidney and urine were largely non‐protein‐bound. A similar pattern was obtained for the low concentration of radioactivity in amniotic fluid. The maternal‐foetal compartments showed negligible bi‐directional transfer of radioactivity.The plasma t1(½) of 125I‐oPL determined here provides evidence that the hormone has a short biological half‐life in sheep. The virtual tack of placental passage of the hormone implies discrete mechanisms for unidirectional secretion of oPL into the two circulatory systems. Our data also suggest the importance of the kidneys in the metabolism of the hormone.
EFFECTS OF COBALT‐CHROME ALLOY WEAR PARTICLES ON THE MORPHOLOGY, VIABILITY AND PHAGOCYTIC ACTIVITY OF MURINE MACROPHAGES IN VITRO
Authors: Garrett R , Wilksch J , Vernon‐Roberts B 
Published: August 2007

SummaryMetallic wear particles were prepared from orthopaedic cobalt‐chrome alloy by milling in medium supplemented with 20% foetal calf serum to maintain particle dispersion. The size distribution of particles was determined by sedimentation and centrifugation and particle concentration was assessed using light extinction. Monolayers of mouse peritoneal macrophages were exposed to metal particles at different concentrations for varying periods. After 4 h of exposure to particle concentrations exceeding 30 μg/ml there was a progressive decline in cell viability, and light and electron microscopy showed that surviving cells had assumed remarkably smooth profiles and contained abundant endocytosed metal. Phagocytic uptake of polystyrene spherules was inhibited markedly by exposure to metal particles even at concentrations at which macrophages remained 100% viable, and preceded the reduction of viability at higher concentrations.The findings are consistent with a pathological role for the metallic wear particles observed frequently within macrophages in the synovial tissues around loose artificial joints in humans.
SPECIFICITY OF PASSIVE SERUM PROTECTION AGAINST NIPPOSTRONGYLUS BRASILIENSIS AND NEMATOSPIROIDES DUBIUS IN MICE
Authors: Brindley Paul J , Dobson Colin 
Published: August 2007

SummaryFewer and smaller worms were recovered from, and significantly fewer parasite eggs were voided by, mice injected with mouse antiserum raised against Nippostrongylus brasiliensis or Nematospiroides dubius after infection with the homologous nematode species compared with the control mice. The passive transfer of protective immunity was specific for the species which induced the antibody response in the donor mice. Passively immunized mice infected with the heterologous nematode species harboured the same number of worms, with the same epg output, as parasites in the control mice, but were stunted. Serological cross‐reactions were observed between the two donor antiserum pools and N. dubius and N. brasiliensis antigens.
THE ENHANCEMENT OF CULTURED SPONTANEOUS CYTOTOXIC T CELLS FROM NORMAL AND ATHYMIC (nu/nu) MICE
Authors: Skinner Margot , Marbrook John 
Published: August 2007

SummarySubsets of natural killer cells may be characterised by the target cell profile, cell surface markers and the effect of growth factors on the production of effector cells. The subset which appears in primary cultures (spontaneous or natural T killer cells) is enhanced by the supernatants of Con A‐stimulated rat spleen cultures. The enhancement can be attributed to an increased number of clones rather than an expansion of clone size in 5‐day cultures. With semi‐purified IL‐2 preparations, clones of spontaneous cytotoxic cells are also detectable in nu/nu spleen cultures. These results suggest such spontaneous cytotoxicity is a general phenomenon within cytotoxic responses.
RAT POST‐IMPLANTATION EMBRYO CULTURE USING HETEROLOGOUS SERUM
Authors: Priscott PK 
Published: August 2007

SummaryIn the present study sera from twelve species have been compared to rat serum and ascitic fluid for their ability to support the growth of post‐implantation rat embryos. No alternative to rat serum or rat ascitic fluid was found. The basis for this apparent species specificity was further analysed. A marked improvement in embryonic growth was seen when rat serum was added to the heterologous serum prior to culture, whereas replenishment of a heterologous serum several times during culture had no effect. The experiments suggested that heterologous sera were nutritionally inadequate but not simply in energy source. Possible mechanisms for the specificity arc discussed.