bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation and characterisation of microsatellites for Xiphinema index using degenerate oligonucleotide primed PCR
Authors: He Yu , Li Hongmei , Brown Derek , Lamberti Franco , Moens Maurice
Published: March 2004

A short insert genomic library for Xiphinema index, the natural vector of
Grapevine Fanleaf Virus, was constructed from degenerate oligonucleotide
primed PCR (DOP-PCR) products. The genomic library was screened for (CA)n
microsatellites. Screening of 6200 colonies and comparison of the sequencing
results revealed seven (CA)n containing microsatellites, coded here as
XIMSL1, XIMSL2, XIMSL3, XIMSL4, XIMSL5, XIMSL6 and XIMSS1. XIMSL prefixed
microsatellites were followed by the motif of the same long interspersed
element. Microsatellite XIMSS1 has some similarity to the short interspersed
element. Except for XIMSL1, all microsatellites were proven to be effective
diagnostic tools at species level. Genetic diversity between and within
populations was also evaluated for each microsatellite.
Trade-off between dispersal and reproduction of a seed-borne nematode, Aphelenchoides besseyi, parasitic on rice plants
Authors: Togashi Katsumi , Hoshino Shigeru
Published: March 2004

The effect of nematode infestation on dispersal and survival of both host plant and parasitic nematode was investigated experimentally using rice plants, Oryza sativa L. and Aphelenchoides besseyi Christie, a seed-borne ectoparasite. Nematode-inoculated plants produced a greater proportion of light seeds floating on water than non-inoculated plants. Nematode mortality was greater in light seeds than in heavy seeds. In the case of light seeds, the mean degree of seed swelling increased as the number of nematodes harboured increased, whereas it was constant with increasing numbers of nematodes for the intermediate and heavy seed groups. A smaller proportion of light seeds germinated and these took longer for seminal roots to protrude than from heavy seeds, irrespective of whether they derived from nematode-inoculated or non-inoculated plants. These results indicate a trade-off for rice seed specific gravity between dispersal and competition of rice seeds and another trade-off between dispersal and reproduction of nematodes harboured in the seed.
Hairy roots to test for transgenic nematode resistance: think twice
Authors: Plovie Eva , De Buck Sylvie , Goeleven Els , Tanghe Miek , Vercauteren Isabel , Gheysen Godelieve
Published: March 2004

Hairy roots induced by Agrobacterium rhizogenes have been proposed as a
versatile, easy and reproducible system for testing nematode resistance in
crop plants. Here, A. rhizogenes was used to induce transgenic hairy roots
on tomato (Lycopersicon esculentum) containing the LEMMI9 cDNA in sense
and/or antisense orientation under control of a nematode responsive
promoter. The purpose was to inhibit the expression of this gene that is
strongly activated in the nematode-induced feeding sites in order to block
their development and, thus, make the plants resistant. Several LEMMI9
transgenic lines produced fewer Meloidogyne incognita second-stage juveniles
than the control lines, but a large variation in progeny was also seen among
the control lines. Therefore, we recommend that several independent
wild-type hairy root lines are generated and tested to obtain a solid
control group for evaluating putative resistance constructs.
Boarding abilities of Bursaphelenchus mucronatus and B. xylophilus (Nematoda: Aphelenchoididae) on Monochamus alternatus (Coleoptera: Cerambycidae)
Authors: Jikumaru Shota , Togashi Katsumi
Published: March 2004

Bursaphelenchus mucronatus is closely related to Bursaphelenchus xylophilus,
the causative agent of pine wilt disease. Both nematodes are transmitted
between host pine trees as the fourth-stage dispersal juveniles (JIV) by
insect vectors. After the invasion of Japan by B. xylophilus, B. mucronatus,
native to Japan, appears to have been replaced in the pine forests during
the spread of the disease. To help understand this species replacement, the
number of JIV carried by an insect vector (the initial nematode load) was
compared between the two nematode species by using the beetle, Monochamus
alternatus, in the laboratory. The initial load of B. mucronatus was
significantly smaller than that of B. xylophilus although the number of
third-stage dispersal juveniles (JIII) concentrated at the pupal chambers
did not differ. Statistical analysis showed that the proportion of JIII
moulting to JIV was the most important among three components explaining the
difference in the initial load of B. mucronatus while the number of JIII
concentrated at the pupal chamber was the most important for B. xylophilus.
The phoretic affinity between the nematode and its vector is discussed in
relation to its role in the species replacement.
Potato cyst nematodes (Globodera rostochiensis and G. pallida) from Swedish potato cultivation - an AFLP study of their genetic diversity and relationships to other European populations
Authors: Manduric Sanja , Andersson Stig
Published: March 2004

Sixteen Swedish PCN populations (nine Globodera rostochiensis and seven G. pallida populations) were compared with 20 other European populations (nine G. rostochiensis and 11 G. pallida populations) from Germany, the Netherlands, Norway and the United Kingdom in an AFLP study. Seven AFLP primer combinations were used to amplify genomic DNAs extracted from cysts. A dendrogram, based on UPGMA and evaluated by bootstrap analysis, contained two main clusters, one for each species. The Swedish Ro1 populations were very similar to corresponding populations from other parts of Europe. Remaining G. rostochiensis populations appeared as a genetically heterogeneous group with two Swedish populations being most dissimilar. Within G. pallida there was strong support for differentiating Pa1 populations from Pa2/3 populations. All Swedish G. pallida populations were grouped in the Pa2/3 cluster, and there were indications that they might have two main European origins. On the whole, the study indicates that there is considerable heterogeneity in Swedish PCN populations, justifying the maintenance of effective phytosanitary regulations.
Three new species of the subfamily Lordellonematinae (Nematoda: Dorylaimida) from Japan
Authors: Ahmad Wasim , Araki Masaaki
Published: March 2004

Three new species belonging to the subfamily Lordellonematinae Siddiqi, 1969 are described and illustrated from Japan. Lordellonema minutum sp. n. has 394-440 μm long body; dorsal and ventral body pores restricted to pharyngeal region; lip region distinctly offset; 11.0-11.5 μm long odontostyle; a thin cardiac disc; pore-like vulva; amphidelphic genital system; short conoid tail with bluntly rounded terminus, and males with spicules lacking median piece and three regularly spaced ventromedian supplements. Sicorinema orientale sp. n. has 490-557 μm long body; lip region distinctly offset; 9.0-9.5 μm long odontostyle with wide aperture; fovea with median support; a thin cardiac disc; pore-like vulva; amphidelphic genital system; short conoid tail, and male with spicules lacking median piece and five regularly spaced ventromedian supplements. Sicorinema caudatum sp. n. has 432-454 μm long body; lip region distinctly offset; 9.0-9.5 μm long odontostyle with wide aperture; fovea with median support; pore-like vulva; amphidelphic genital system and elongate conoid tail. The males are reported for the first time for both Lordellonema Andrássy, 1960 and Sicorinema Siddiqi, 1982 and consequently the diagnoses of both genera are emended. A diagnostic compendium of the species of the genus Sicorinema is also provided.
Management of Meloidogyne graminicola and yield of upland rice in South-Luzon, Philippines
Authors: Soriano Imelda , Reversat Georges
Published: March 2004

Meloidogyne graminicola, the rice root-knot nematode, has become a constraint on Asian rice production due to rice cropping intensification and increasing scarcity of water. This work relates to the assessment of crop rotation, fallow and nematicide treatments in naturally infested fields to manage M. graminicola populations and prevent yield losses. One or two consecutive crops of cowpea or seasons of fallow before a rice crop lowered nematode populations and improved rice yield by 30-80%. Methyl bromide was used to determine yield potential and almost eradicated the nematode, trebling rice yield. Carbofuran improved yield of the first rice crop but did not affect the second rice crop. Due to its short life cycle, M. graminicola populations were similar after only a single rice crop and after three consecutive crops. It is recommended that, to ensure higher rice yields, M. graminicola populations should be maintained at low density by non-host crop rotations or fallows, ideally for two seasons before planting rice.
Soil factors determined nematode community composition in a two year pot experiment
Authors: Griffiths Bryan , Neilson Roy , Bengough A. Glyn
Published: March 2004

Two similar, sandy loam soils from the same geographical region but with
distinct nematode communities were used to determine the extent to which
water, soil and inoculum factors affected nematode community structure.
Treatments were established in pots containing a middle layer of frozen
defaunated soil, sandwiched between an inoculum that was either fresh soil
from the same site ('self') or a mixture of soils to give a more diverse
inoculum ('mixed'). During year 2, half the pots were watered at regular
intervals while the other half received only rainfall. For individual
nematode taxa, soil layer and watering regime were the main factors
discriminating between treatments, while initial inoculum had a larger
influence than soil type. Acrobeloides was most affected by the watering
regime, being more abundant under variable water conditions, whereas
Hoplolaimidae, Longidorus and Pratylenchus were more abundant in deeper soil
layers in contrast to other taxa. For the community as a whole, when
analysed by principal component analysis, soil factors clearly influenced
composition and also indicated that the biological properties of the soils
were important.
Speleothem master chronologies: combined Holocene 18O and 13C records from the North Island of New Zealand and their palaeoenvironmental interpretation
Authors: Williams P. W. , King D. N.T. , Zhao J.-X. , Collerson K. D.
Published: February 2004

The stable isotope records of four stalagmites dated by 19 TIMS uranium series ages are combined to produce master chronologies for δ 18O and δ 13C. The δ 18O records display good overall coherence, but considerable variation in detail. Variability in the δ 13C records is greater, but general trends can still be dis cerned. This implies that too fine an interpretation of the structure of individual isotopic records can be unreliable. Speleothem δ 18O values are demonstrated to show a positive relationship with temperature by comparing trends with other proxy records, but also to respond negatively to rainfall amount. Speleothem δ 13C is con sidered to be most influenced by rainfall. The postglacial thermal optimum occurred around 10.8 ka BP, which is similar in timing to Antarctica but up to 2000 years earlier than most Northern Hemisphere sites. Increasingly negative δ 18O values after 7.5 ka BP indicate that temperatures declined to a late mid-Holocene minimum centred around 3 ka BP, but more positive values followed to mark a warm peak about 750 years ago which coincided with the ‘Mediaeval Warm Period’ of Europe. Low δ 18O values at 325 years BP suggest cooling coincident with the ‘Little Ice Age’. A marked feature of the δ13C record is an asymmetric periodicity averaging c. 2250 years and amplitude of c. 1.9‰. It is concluded that this is mainly driven by waterbalance variations with negative swings representing particularly wet intervals. The δ18O record shows a higher-frequency cyclicity with a period of c. 500 years and an amplitude of c. 0.25‰. This is most likely to be temperature-driven, but some swings may have been amplified by precipitation.
New Zealand climate over the last 500 years reconstructed from Libocedrus bidwillii Hook. f. tree-ring chronologies
Authors: Palmer Jonathan G. , Xiong Limin
Published: February 2004

Five Libocedrus bidwillii Hook. f. tree-ring chronologies were used to reconstruct‘late’ New Zealand summer (February–March) temperatures from the present to ad 1459. The reconstructed series showed that warm periods occurred around the 1470s, 1530s, 1570s, 1600s, 1730–1780, 1820–1840, 1870s, 1920–1940 and the 1960s onwards. The cooler periods were around 1630–1680, 1790–1810, 1880–1910 and 1950. The temperature reconstruction correlates significantly with others from New Zealand and to the associated part of the 1089-year temperature reconstruction from Huon pine ( Lagarostrobos franklinii C.J. Quinn) in Tasmania. The general palaeotemperature trend is also similar to a temperature series derived from oxygen isotope ratios in a New Zealand speleothem, providing an example of preliminary corroboration between two different types of proxy-climate indicators.
Laser granulometry of Holocene estuarine silts: effects of hydrogen peroxide treatment
Authors: Allen J. R.L. , Thornley D. M.
Published: February 2004

The Holocene estuarine silts of the Severn Estuary Levels (southwest Britain) are representative of their kind in northwest Europe. They contain two broad types of plant material: particles codeposited with mineral grains from the estuarine water body, and extraneous debris (stems of indigenous prior plants; post depositional root matter) which is difficult to remove completely by physical means. Treatment with hydrogen peroxide before laser granulometry removes all plant material regardless of kind, drastically reduces values for the mean grain size and median size relative to untreated samples, but has little effect on the mode, except for a restricted group of bimodal-platykurtic, medium-coarse silts. It is concluded that, in the case of sediments of the general kind examined, no advantages acrue from the treatment of samples with hydrogen peroxide prior to analysis. Although a discrete rather than continuous variable, values of the mode obtained from untreated sediments are suggested to be acceptable for most purposes where a measure of central tendency is required.
Late-Holocene Atlantic bottom-water variability in Igaliku Fjord, South Greenland, reconstructed from foraminifera faunas
Authors: Lassen Susanne J. , Kuijpers Antoon , Kunzendorf Helmar , Hoffmann-Wieck Gerd , Mikkelsen Naja , Konradi Peter
Published: February 2004

A high-resolution record of late-Holocene subsurface water-mass characteristics in outer Igaliku Fjord, South Greenland, is presented based on benthic foraminifera faunas from core PO 243–451 collected from a water depth of 304 m. Strati” cation with Atlantic water masses present in the lower part of the water-column is suggested to have prevailed during the last 3200 cal. years, except for a period referred to as the‘Mediaeval Warm Period’ (MWP). During the MWP (c. ad 885–1235) the outer part of Igaliku Fjord experienced enhanced vertical mixing and a high hydrodynamic energy level which we ascribe to increasing wind stress through this period, corresponding to the period of the Norse settlement. The transition from the MWP to the‘Little Ice Age’ (LIA) shows a two-step pattern with a short climatic amelioration around AD 1520 before maximum cooling occurred. The intensified wind stress and the overall environmental change are suggested to have contributed to the loss of the Norse settlement in Greenland. Periods with strong stratification and marked in uence of Atlantic subsurface water masses around 2.6, 1.3 ka BP and during the LIA are correlated to North Atlantic Holocene ice-rafting events reported by Bond et al. (1997).
Sensing small-scale human activity in the palaeoecological record: fine spatial resolution pollen analyses from Glen Affric, northern Scotland
Authors: Davies Althea L. , Tipping Richard
Published: February 2004

This paper examines the importance of palynological site selection criteria, speci”cally basin size, for the detection of vegetation mosaics and small- or local-scale human activity within a spatially diverse, mosaic landscape. Using a site selection strategy which recognizes landscape patchiness, pollen analyses from three small peat basins (10–56 m diameter) in an open, exposed upland valley (>250 m OD) provide records which are sensitive to local vegetation mosaics and small-scale, localized agriculture. The results indicate c. 4000 14C years (4400 cal. years) of land use, with spatial and temporal variations in the valley. Contrasts between the sequences suggest that local pollen production remains an important component of the pollen rain deposited in small peat basins, even in open environments; this is especially true of palynological‘agricultural indicators’. By comparison, sites with regional pollen source areas underestimate the spatial diversity of the upland landscape, and are insensitive to small-scale human activity in an environment where the fragmentary distribution of soils suitable for agriculture favoured a small-scale, dispersed pattern of farming. It is therefore essential to match the spatial resolution of pollen records with the grain size or scale of variations in the environment under investigation in order to sense the scale of mosaics in vegetation and agriculture within patchy landscapes.
Coastal oceanographic conditions in the Prydz Bay region (East Antarctica) during the Holocene recorded in an isolation basin
Authors: Verleyen Elie , Hodgson Dominic A. , Sabbe Koen , Vanhoutte Koenraad , Vyverman Wim
Published: February 2004

Information on East Antarctic coastal environments during the Holocene is relatively sparse. This is surprising as sedimentary records from the interface between land and sea can provide chronologies of climatic change, isostatic uplift, relative sea level and the colonization of newly formed biomes. Here we examine a sediment core from Pup Lagoon, a coastal lake in the Larsemann Hills, East Antarctica. Sediment stratigraphy, fossil pigments and diatoms were used to infer the sequence of Holocene environmental and climatic change. Results show that between 5800 and 5500 cal. yr BP the marine coast of Prydz Bay was characterized by stratified, open-water conditions during spring and summer and seasonally warm conditions. From 5500 to 2750 cal. yr BP sea-ice duration in Prydz Bay increased with the coast being ice-free for 2–3 months each year, conditions which are similar to the present day. A return to stratified, open-water conditions and a reduction in winter sea-ice extent between 2750 and 2200 cal. yr BP is signalled by enhanced biogenic production and more open-water diatom taxa. This is consistent with evidence for the mid-Holocene Hypsither mal detected in other records in East Antarctica. Isostatic isolation of the Pup Lagoon basin from the sea between 2200 and 2000 cal. yr BP slightly precedes the emergence of lakes with comparable sill heights from the nearby Vestfold Hills. The colonization of Pup Lagoon after its isolation as a freshwater lake was initiated by a siliceous flora dominated by stomatocysts with microbial mat development being prevented by mechanical or physical stress. A brief period of marine incursion following the mid-Holocene Hypsithermal may be related to local events such as iceberg calving or to minor sea-level change. Weighted averaging regression, used to infer salinity in the lacustrine zone, shows that from 1500 cal. yr BP Pup Lagoon is a freshwater lake, where the flora is dominated by stratified cyanobacterial mats, with green algae and diatoms as co-dominants, comparable to modern Pup Lagoon and other lakes in the Larsemann Hills.
Midge-inferred Holocene climate history of two subalpine lakes in southern British Columbia, Canada
Authors: Rosenberg Sandra M. , Walker Ian R. , Mathewes Rolf W. , Hallett Douglas J.
Published: February 2004

To investigate postglacial environmental changes in both the coastal and interior wet belts of British Columbia, fossil midges were analysed from two subalpine lakes, one adjacent to the lower Fraser canyon (Frozen Lake), and the other in Mount Revelstoke National Park (Eagle Lake). The midge stratigraphy for Frozen Lake revealed an abundance of rheophilous chironomid taxa and Simuliidae larvae, refecting the presence of an inflowing stream. An abundance of Chaoborus mandibles and Microtendipes during the early Holocene (c. 10100–7700 14C years BP, c. 11500–8500 cal. years BP) suggests warmer temperatures. A subsequent decline in the warm indicators and relative increases in cold stenotherms (Heterotrissocladius and Diamesa) indicate cooling until present day. This climate reconstruction is consistent with other quantitative and qualitative evidence for past climatic change in southern British Columbia. At Eagle Lake the warm indicators, Dicrotendipes and Polypedilum, are seen in the early Holocene (c. 8500–6730 14C years BP, c. 9600–7600 cal. years BP), but are absent during the mid-Holocene when cooler temperatures probably prevailed. In the late Holocene (c. 3800 14C years BP to present, c. 4200 cal. years BP to present) there is a resurgence of warm indicators, which contrasts with the evidence of continued cooling typically seen in reconstructions of southern British Columbia summer temperatures. The Eagle Lake record therefore appears to be anomalous. Multiproxy and multisite investigations are needed to reconstruct Holocene climatic changes more reliably.
The intercept is a poor estimate of a calibrated radiocarbon age
Authors: Telford R. J. , Heegaard E. , Birks H. J.B.
Published: February 2004

Intercept-based methods of generating a point estimate of a calibrated radiocarbon date are very popular, but exhibit undesirable behaviour. They are highly sensitive to the mean of the radiocarbon date and to adjustments of the calibration curve. Other methods give more stable results. The weighted average of the probability distribution function is recommended as the best central-point estimate, but more consideration should be given to using the full probability distribution rather than a point estimate in developing age-depth models.
Were abrupt Lateglacial and early-Holocene climatic changes in northwest Europe linked to freshwater outbursts to the North Atlantic and Arctic Oceans?
Authors: Nesje Atle , Dahl Svein Olaf , Bakke Jostein
Published: February 2004

During the Lateglacial and early Holocene, abrupt, millennial-scale climatic variations are recorded in a wide range of high-resolution proxy records from marine and terrestrial archives in NW Europe. Our review of the evidence for these rapid climate events do not show an apparent link to possible forcing factors such as long-term, orbitally induced variations in solar radiation, short-term variations in solar activity as inferred from 14C, atmospheric carbon dioxide concentration, or volcanic sulphate as recorded in the GISP2 ice-core record. There is, however, a remarkable degree of similarity with the number, duration and timing of episodes of increased flux of fresh water to the north Atlantic and Arctic Oceans from the Laurentide ice sheet and from the Baltic ice lake in SW Sweden. These freshwater outburst events occurred when continental runoff from the Laurentide ice sheet was rerouted from the Mississippi River to the Hudson River, St Lawrence River, Hudson Strait and along the Mackenzie River to the Atlantic and Arctic Oceans, and when the Baltic ice lake in SW Sweden drained to Skagerrak. Periods of increased freshwater flow to the North Atlantic and Arctic Oceans may thus provide a mechanism to explain the abrupt and significant Lateglacial and early Holocene climate events in NW Europe. The idea that freshwater outbursts might drive abrupt climate events is not new, but previous work may have underestimated the extent of support from proxy data and overestimated the influence of the Laurentide ice sheet.
The biomechanics of vertebroplasty: A review
Authors: Wilcox R K
Published: March 2004

Percutaneous vertebroplasty and kyphoplasty are being used extensively in the United States for the treatment of osteoporotic vertebral compression fractures. Although short-term clinical outcomes appear favourable, long-term data are not yet available and it is becoming increasingly important to understand how the underlying biomechanics of the spine are altered by the procedure. In vitro experimental studies have investigated the effect of cement augmentation on individual vertebra and short spinal segments. For individual vertebra, vertebroplasty appears to increase or return strength to the prefracture level, whereas the stiffness is not always restored. However for multiple-vertebra segments, the strength of the unit as a whole appears to decrease, with failure occurring in the non-augmented vertebrae. Both finite element (FE) and experimental studies have shown that the volume of cement injected affects the restoration of strength and stiffness. The type of cement appears to have less of an effect. Although biomechanical studies of the vertebroplasty process have indicated that the procedure has the potential to restore vertebral strength and stiffness, further work is necessary to understand fully the effects of the augmentation process on the surrounding structures if the treatment is to be fully optimized. This paper is a review of the biomechanical data available on vertebroplasty.
Assessment of cement introduction and pressurization techniques
Authors: Dunne N J , Orr J F , Beverland D E
Published: March 2004

The objective of this study was to measure the medullary pressures generated during bone cement injection, pressurization and femoral prosthesis insertion. The measurements were recorded throughout the length of an in vitro femoral model while implanting a series of prosthetic hip stems using different pressurization techniques. The prostheses used were a Charnley 40 flanged stem (Johnson & Johnson DePuy International Limited), an Exeter No. 3 stem (Stryker Howmedica Osteonics, Howmedica International Limited), and a customized femoral component (Johnson & Johnson DePuy International Limited). The following parameters were derived from the pressure data recorded: peak pressure, decay pressure and duration above optimum pressure of 76 kPa to predict adequate penetration.

The custom and Exeter stems generated cement pressures throughout the length of the cavity model that were predicted to achieve adequate bone cement interdigitation into cancellous bone. For all the conditions investigated in this study, when using the Charnley femoral component, an adequate level of cement pressurization was generated in the medial-distal portion of the femoral cavity. It is postulated that this could result in reduced integration of the cement mantle with bone and less effective transmission of functional loads applied during a patient's normal activity, postoperatively.
Analysis of elastohydrodynamic lubrication in McKee—Farrar metal-on-metal hip joint replacement
Authors: Yew A , Udofia I , Jagatia M , Jin Z M
Published: March 2004

An elastohydrodynamic lubrication (EHL) analysis was carried out in this study for a typical McKee-Farrar metal-on-metal hip prosthesis under a simple steady state rotation. The finite element method was used initially to investigate the effect of the cement and bone on the predicted contact pressure distribution between the two articulating surfaces under dry conditions, and subsequently to determine the elastic deformation of both the femoral and the acetabular components required for the lubrication analysis. Both Reynolds equation and the elasticity equation were coupled and solved numerically using the finite difference method. Important features in reducing contact stresses and promoting fluid-film lubrication associated with the McKee-Farrar metal-on-metal hip implant were identified as the large femoral head and the thin acetabular cup. For the typical McKee-Farrar metal-on-metal hip prosthesis considered under typical walking conditions, an increase in the femoral head radius from 14 to 17.4 mm (for a fixed radial clearance of 79 μn) was shown to result in a 25 per cent decrease in the maximum dry contact pressure and a 60 per cent increase in the predicted minimum film thickness. Furthermore, the predicted maximum contact pressure considering both the cement and the bone was found to be decreased by about 80 per cent, while the minimum film thickness was predicted to be increased by 50 per cent. Despite a significant increase in the predicted minimum lubricating film thickness due to the large femoral head and the thin acetabular cup, a mixed lubrication regime was predicted for the McKee Farrar metal-on-metal hip implant under estimated in vivo steady state walking conditions, depending on the surface roughness of the bearing surfaces. This clearly demonstrated the important influences of the material, design and manufacturing parameters on the tribological performance of these hard-on-hard hip prostheses. Furthermore, in the present contact mechanics analysis, the significant increase in the elasticity due to the relatively thin acetabular cup was not found to cause equatorial contact and gripping of the ball.
Elimination of the friction effects in unconfined compression tests of biomaterials and soft tissues
Authors: Wu J Z , Dong R G , Smutz W P
Published: March 2004

The mechanical properties of biomaterials and soft tissues are determined conventionally using unconfined compression tests. In such tests, frictionless specimen/platen contact in unconfined compression tests has to be assumed in determining the material properties of the materials. Previous theoretical analysis demonstrated, however, that the effects of the friction at the specimen/platen contact interface on the measured stress responses are non-negligible. In this study, a computational approach was proposed to eliminate the effects of friction. The friction coefficient between the specimen and the compression platens is measured first. Using a finite element model, the stress strain relationship, without the influence of the friction effects, can be derived from the experimental data obtained in conventional unconfined compression tests. In order to validate the proposed approach, unconfined compressive tests of rubber have been performed.
A machine for the preliminary investigation of design features influencing the wear behaviour of knee prostheses
Authors: McGloughlin T M , Murphy D M , Kavanagh A G
Published: March 2004

Degradation of tibial inserts in vivo has been found to be multifactorial in nature, resulting in a complex interaction of many variables. A range of kinematic conditions occurs at the tibio-femoral interface, giving rise to various degrees of rolling and sliding at this interface. The movement of the tibio-femoral contact point may be an influential factor in the overall wear of ultra-high molecular weight polyethylene (UHMWPE) tibial components. As part of this study a three-station wear-test machine was designed and built to investigate the influence of rolling and sliding on the wear behaviour of specific design aspects of contemporary knee prostheses. Using the machine, it is possible to monitor the effect of various slide-roll ratios on the performance of contemporary bearing designs from a geometrical and materials perspective.
In vitro characterization of the relationship between the Q-angle and the lateral component of the quadriceps force
Authors: Elias J J , Mattessich S M , Kumagai M , Mizuno Y , Cosgarea A J , Chao E Y
Published: March 2004

Although the Q-angle is routinely measured, the relationship between the Q-angle and the lateral component of the quadriceps force acting on the patella is unknown. Five cadaver knees were flexed on a knee simulator with a normal Q-angle, and flexed after increasing and decreasing the Q-angle by shifting the quadriceps origin laterally and medially, respectively. The motion of the femur, tibia and patella was tracked from 20 to 90° of flexion using electromagnetic sensors. The motion of landmarks used to quantify the Q-angle was tracked to determine the ‘dynamic Q-angle’ during flexion. The lateral component of the force applied by the actuator secured to the quadriceps tendon was also quantified throughout flexion. Increasing the initial Q-angle significantly (p < 0.05) increased the dynamic Q-angle and the lateral force exerted through the quadriceps tendon throughout flexion. Decreasing the initial Q-angle significantly decreased the dynamic Q-angle at 90° of flexion and significantly decreased the lateral force exerted through the quadriceps tendon from 20 to 40° of flexion. Even though the dynamic Q-angle changes during flexion, an abnormally large initial Q-angle can be an indicator of an abnormally large lateral force acting on the patella during flexion.
Effect of twisting hamstring tendon grafts on strength and joint laxity through the range of knee movement
Authors: Sidwell A , Wilson D , Wild P
Published: March 2004

Twisting or braiding of hamstring tendon grafts for use in anterior cruciate ligament reconstructions has been advocated to increase their strength and stiffness under load. In this study, a two-dimensional model was used to determine the failure strength of twisted and parallel grafts and associated knee laxity under simulated physiological loading conditions. For validation, mechanical tests of tendon grafts were also simulated with these models. The simulated physiological loading of the graft models showed that knees with twisted grafts had greater laxity than knees with parallel grafts, although there was little difference in failure load between the two graft configurations. The tensile loading of the graft models showed little difference in failure load when the tendons were modelled using line segments. When the tendons were considered as three-dimensional helical elements, which more accurately describe the tendon structure, the failure load of the twisted graft decreased significantly. This research provided no evidence to support the belief that a twisted tendon graft is a superior graft configuration relative to a parallel tendon graft.
Morphology of the radial head: A reverse engineering based evaluation using three-dimensional anatomical data of radial bone
Authors: Mahaisavariya B , Saekee B , Sitthiseripratip K , Oris P , Tongdee T , Bohez E L , Vander Sloten J
Published: March 2004

The proximal part of the radius has a complex shape and dimension that cannot be precisely determined by standard roentgenogram for real three-dimensional anatomical shape which is important for prosthesis design. This study presents a method by which computer tomography (CT) images are combined with the reverse engineering technique to obtain and analyse the three-dimensional inner and outer geometry of the proximal radius. The three-dimensional models were reconstructed from CT images obtained from 40 radial bones and approximated with two- and three-dimensional fitting algorithms based on reverse engineering methods. The mean total length of the radius was 240.0mm [standard deviation (SD) = 17.3]. The radial head in this study is more likely to be circular with an average diameter of 20.5 mm (SD = 1.9). The outer diameter of the radial neck averages 14.7 mm (SD = 1.0). The thickness of the radial head averages 12.9 mm (SD = 1.4). The intramedullary canal diameter of the radial neck averages 7.4 mm (SD = 1.4). The depth of the fossa at the articular surface averages 1.5 mm (SD = 0.4).
Adjuvant medical therapy to deep venous reconstruction
Authors: Boudouroglou D , Kakkos S K , Geroulakos G
Published: March 2004

No randomized controlled clinical trials have investigated the role of postoperative adjuvant medical therapy in improving the results of deep venous reconstruction. Deep venous thrombosis (DVT) is an important complication following deep valve reconstruction. It may occur at the site of the repaired valve or alternatively in remote sites. There is evidence from randomized controlled trials in many surgical specialties indicating that the combination of anticoagulation and a mechanical method of prophylaxis has an important role in the reduction of postoperative DVT. This combination should be used in the postoperative management of deep venous reconstruction. Additional benefits of the mechanical methods of thromboprophylaxis are a reduction of the postoperative swelling and improved venous haemodynamics.
Fibrinolytic and biochemical factors in patients with venous insufficiency
Authors: Boisseau M R , Khodabandehlou T , Le Dévéhat C
Published: March 2004

Long-term metabolic changes in vein tissue of the limbs and feet have been reported in the course of chronic venous insufficiency (CVI). Low fibrinolytic potential was first demonstrated using fibrin-embedded vein rings (Todd's biopsy), then in blood via increased euglobulin lysis time. This defect is especially pronounced when blood is taken from foot veins of patients with grades 5 and 6 of CVI or skin lesions. Haemorrheological disorders such as increased blood viscosity and red cell aggregation, related mainly to high fibrinogen levels, have also been shown in patients with CVI. Such disorders, particularly observed in blood from foot veins, play an important role in the interaction between the blood cell components and the vessel wall.

More recently, the margination and adhesion of white cells to the endothelium and the subsequent activation of white cells have been assumed. Adhesion molecules such as ICAM-1, VCAM-1 and P-selectin have been identified surrounding skin ulceration. There is also evidence that markers of neutrophil degranulation reach high levels in blood taken from foot veins after exposure to experimental venous hypertension. White cell activation results in elevated plasma levels of L-selectin, increased production of oxygen free radicals, pseudopods, CD11b integrin, platelet-monocyte aggregates and abnormal lymphocyte L-selectin. Increased nitric oxide, presumably due to monocyte activation, as well as increased urine haemosiderin related to skin microvessel leakage have also been reported. VCAM-1 and metalloproteinase MMP9 activity have been stated as sensitive markers in relation to endothelium activation and white cell trapping, which follows hypoxia and/or alterations in wall shear stress, mainly in skin venulae and in the region of valves.
Mesenteric venous thrombosis
Authors: Stansby G , Overbeck K
Published: March 2004

Mesenteric venous thrombosis is a rare condition associated with a high rate of morbidity and mortality. There have been no randomized trials, but most recent authors advocate the combination of a high clinical index of suspicion combined with noninvasive imaging with computerized tomography to make the diagnosis. When there is no evidence of perforation or peritonitis the condition is best managed conservatively with anticoagulation treatment.
Deep venous reflux and incompetent perforators: significance and implications for therapy
Authors: Labropoulos N , Leon L , Rodriguez H , Kang S S , Mansour A M , Littooy F N
Published: March 2004

Objectives: To define the significance of perforator and deep vein pathology in patients with chronic venous disease (CVD).

Methods: Consecutive patients with CVD were referred for venous evaluation (group A). Both saphenous veins and all the deep veins including those in the calf area were evaluated. A separate group of patients with deep venous reflux and/or obstruction was identified from our database and analysed separately (group B). The CEAP classification (clinical, aetiological, anatomical and pathological) was used to grade the clinical severity of CVD.

Results: Age, duration of disease and history of thrombosis increased significantly with disease severity ( P <0.02). Reflux in the superficial veins was the most common pathology in group A and it was present in 75% of limbs in group B. The overall contribution of deep venous disease was 26% in group A and it increased significantly with the severity of disease in both groups. Isolated deep vein disease in group A was significantly less compared with group B (8% vs 23%, P<0.0001). Reflux in deep veins of post-thrombotic limbs was significantly longer compared with those with primary disease. The prevalence of incompetent perforator veins was higher in patients with skin damage from both groups. No patient had isolated perforator vein reflux. Reflux was the most common pathology in both groups, while obstruction alone was rare. Other than superficial reflux, which is very common, ipsilateral recurrent deep venous thrombosis (DVT), combined reflux and obstruction, and popliteal vein reflux were the strongest predictors for development of skin damage.

Conclusions: Perforator and deep vein involvement increases significantly with the severity of CVD. Isolated deep vein disease in post-thrombotic limbs is more common than in consecutive venous patients. Reflux is the most common pathology and obstruction alone is rare. In post-thrombotic limbs, the most important predictors for skin damage are ipsilateral recurrent DVT, popliteal vein reflux and a combination of reflux and obstruction.
Endoscope-assisted management of primary varicose veins of the long saphenous vein and its tributaries
Authors: Lin S-D , Yang Y-L , Lee S-S , Chang K-P , Lin T-M , Lai C-S
Published: March 2004

Objective: Primary varicose veins of the long saphenous vein and its tributaries were managed in 104 limbs of 101 patients with the assistance of endoscopic surgery.

Methods: Patients were divided into four clinico-anatomical types according to normal veins involved in the varicosities. With good illumination and magnified monitor viewing by means of a surgical endoscope, the varicositic trunk, varicositic tributaries, incompetent perforating veins and healthy veins could be clearly visualized and identified. Through two or more access incisions (2.5-3.0 cm in length), the varicose veins were completely dissected, divided and removed. The incompetent perforating veins were clipped and divided. In all cases, the mean number of incisions in each limb was 3.0.

Results: The most common cause of morbidity was maceration of the incision wound. Transient numbness may have presented at the dissected area, but there were no signs of injury to the saphenous nerve.

Conclusions: There was very little possibility of recurrence, because no residual varicosities or incompetent perforating veins remained after this operation. Recurrence presented in only one case at follow up, three months postoperatively. Patients were satisfied with the minimal surgical scarring and complete absence of disfiguring varicosities in the limb.
Clinical and anatomical findings of acute iliofemoral deep venous thrombosis
Authors: Saarinen J , Anturaniemi M , Heikkinen M , Suominen V , Salenius J-P
Published: March 2004

Objective: To observe the clinical and anatomical features of acute iliofemoral deep venous thrombosis (DVT).

Methods: A consecutive sample of phlebographically confirmed DVT cases during a 25-month period were retrospectively assessed. There were 390 DVT cases, including 73 patients with iliofemoral DVT. The phlebograms of iliofemoral DVTs were reviewed and the location of the thrombus mapped. The patients' files were completely reviewed in all patients with DVT, including concomitant diseases and mortality after the diagnosis of DVT.

Results: The average age of the patients with iliofemoral DVT was 63 years compared with 57 years in the cases of infrainguinal DVT ( P<0.005). Left : right-ratio was 2.43 in iliofemoral DVTs, and 1.42 in infrainguinal cases ( P<0.005). Iliofemoral DVT cases were multisegmental (from calf into iliac veins) in 92% of the legs. The aetiology of iliofemoral DVT was idiopathic in 55%, surgery in 14%, malignancy in 14%, immobilization in 10%, trauma in 5%, coagulation disorder in 1% and pregnancy in 1% of the cases. No concomitant diseases were noted in 32% of the patients with iliofemoral DVT, and the corresponding finding in the subgroup of infrainguinal DVTs was 57%. The incidence of death within one-year was 18% and 8% in the subgroups of iliofemoral and infrainguinal DVT. In patients with a combination of iliofemoral DVT and malignancy,the incidence of death within one-year was 80%.

Conclusions: According to anatomical findings iliofemoral DVT is typically left-sided and multisegmental. However, clinical findings show that patients with this condition are relatively aged, and the frequency of concomitant diseases is high. The prognosis among the patients with pre-existing malignant disease was very poor. Prevention of post-thrombotic syndrome by using invasive treatment should be considered only in selected cases.
Complete resection of leiomyosarcoma of the suprarenal inferior vena cava without caval replacement
Authors: Minakuchi H , Iwai T , Inoue Y , Sugano N , Takiguchi N
Published: March 2004

Objective: To successfully treat leiomyosarcoma of the suprarenal segment of the inferior vena cava (IVC) by section without caval replacement.

Methods: Multiple occlusive clamps were used to maintain haemodynamic stability. Measurement of the stump pressure of the distal IVC and both renal veins was employed to evaluate venous congestion.

Results: Use of these techniques allowed avoidance of suprarenal IVC reconstruction in our patient, who had well-developed collateral veins.

Conclusions: Our experience indicates that reconstruction is not always mandatory.
Doppler tomography of Algols
Authors: Richards M. T.
Published: March 2004

The technique of Doppler tomography has been influential in the study of mass transfer in Algol‐type interacting binaries. The Algols contain a hot blue dwarf star with a magnetically‐active late‐type companion. In the close Algols, the gas stream flows directly into the photosphere of the blue mass‐gaining star because it does not have enough room to avoid impact with that star. Doppler tomograms of the Algols have been produced from over 2500 time‐resolved spectra at wavelengths corresponding to Hα, Hβ, He I (6678 Å), Si II (6371 Å) and Si IV (1394 ° A). These tomograms display images of accretion structures that include a gas stream, accretion annulus, accretion disk, stream‐star impact region, and occasionally a source of chromospheric emission associated with the cool, mass‐losing companion. Some Algol systems alternate between streamlike and disk‐like states, and provide direct evidence of active mass transfer within the Algols. This work produced the very first images of the gas stream for the entire class of interacting binaries, and demonstrated that the Algols are far more active than formerly believed, with variability on time scales of weeks to months. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Echo mapping of active galactic nuclei
Authors: Peterson B. M. , Horne K.
Published: March 2004

Echo mapping makes use of the intrinsic variaibility of the continuum source in active galactic nuclei to map out the distribution and kinematics of line‐emitting gas from its light travel time‐delayed response to continuum changes. Echo mapping experiments have yielded sizes for the broad line‐emitting region in about three dozen AGNs. The dynamics of the line‐emitting gas seem to be dominated by the gravity of the central black hole, enabling measurement of the black‐hole masses in AGNs. We discuss requirements for future echo‐mapping experiments that will yield the high‐quality velocity–delay maps of the broad‐line region that are needed to determine its physical nature. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)