bluuebunny/crossref_metadata_2025 huggingface dataset:
Host specificity of a generalist parasite: genetic evidence of sympatric host races in the seabird tickIxodes uriae
Authors: Mccoy K. D. , Boulinier T. , Tirard C. , Michalakis Y.
Published: March 2003

Due to the close association between parasites and their hosts, many ‘generalist’ parasites have a high potential to become specialized on different host species. We investigated this hypothesis for a common ectoparasite of seabirds, the tick Ixodes uriae that is often found in mixed host sites. We examined patterns of neutral genetic variation between ticks collected from Black-legged kittiwakes (Rissa tridactyla) and Atlantic puffins (Fratercula arctica) in sympatry. To control for a potential distance effect, values were compared to differences among ticks from the same host in nearby monospecific sites. As predicted, there was higher genetic differentiation between ticks from different sympatric host species than between ticks from nearby allopatric populations of the same host species. Patterns suggesting isolation by distance were found among tick populations of each host group, but no such patterns existed between tick populations of different hosts. Overall, results suggest that host-related selection pressures have led to the specialization of I. uriae and that host race formation may be an important diversifying mechanism in parasites.
Differential gene exchange between parapatric morphs of Littorina saxatilis detected using AFLP markers
Authors: Wilding C. S. , Butlin R. K. , Grahame J.
Published: March 2003

Speciation requires the acquisition of reproductive isolation, and the circumstances under which this could evolve are of great interest. Are new species formed after the acquisition of generalized incompatibility arising between physically separated populations, or may they arise as a result of the action of disruptive selection beginning with the divergence of a rather restricted set of gene loci? Here we apply the technique of amplified fragment length polymorphism (AFLP) analysis to an intertidal snail whose populations display a cline in shell shape across vertical gradients on rocky shores. We compare the FST values for 306 AFLP loci with the distribution of FST estimated from a simulation model using values of mutation and migration derived from the data. We find that about 5% of these loci show greater differentiation than expected, providing evidence of the effects of selection across the cline, either direct or indirect through linkage. This is consistent with expectations from nonallopatric speciation models that propose an initial divergence of a small part of the genome driven by strong disruptive selection while divergence at other loci is prevented by gene flow. However, the pattern could also be the result of differential introgression after secondary contact.
Multiple infection dynamics has pronounced effects on the fitness of RNA viruses
Authors: Miralles R. , Ferrer R. , Solé R. V. , Moya A. , Elena S. F.
Published: March 2003

Several factors play a role during the replication and transmission of RNA viruses. First, as a consequence of their enormous mutation rate, complex mixtures of genomes are generated immediately after infection of a new host. Secondly, differences in growth and competition rates drive the selection of certain genetic variants within an infected host. Thirdly, but not less important, a random sampling occurs at the moment of viral infectious passage from an infected to a healthy host. In addition, the availability of hosts also influences the fate of a given viral genotype. When new hosts are scarce, different viral genotypes might infect the same host, adding an extra complexity to the competition among genetic variants. We have employed a two-fold approach to analyse the role played by each of these factors in the evolution of RNA viruses. First, we have derived a model that takes into account all the preceding factors. This model employs the classic Lotka-Volterra competition equations but it also incorporates the effect of mutation during RNA replication, the effect of the stochastic sampling at the moment of infectious passage among hosts and, the effect of the type of infection (single, coinfection or superinfection). Secondly, the predictions of the model have been tested in an in vitro evolution experiment. Both theoretical and experimental results show that in infection passages with coinfection viral fitness increased more than in single infections. In contrast, infection passages with superinfection did not differ from the single infection. The coinfection frequency also affected the outcome: the larger the proportion of viruses coinfecting a host, the larger increase in fitness observed.
Population divergence of developmental thermal optima in Swedish common frogs, Rana temporaria
Authors: Ståhlberg F. , Olsson M. , Uller T.
Published: March 2003

Growth rate, like any other trait, should be under balancing selection in natural populations, with selection adjusting mean growth rate in a population in relation to its site-specific costs and benefits. In the present study, we tested for differences in thermal growth optima between a northern and a southern region of Rana temporaria by rearing tadpoles in three different temperatures in the laboratory (10, 15 and 20 °C). Because of the rapid increase in post-melt temperature at high latitudes, spawn and tadpoles from the northern region experience significantly higher minimum, mean and maximum temperature throughout the period of pre-metamorph development. Frogs up north also enjoys a shorter breeding season and activity season overall. This suggests that growth and development should be maximized at a relatively higher temperature in the north as a result of directional selection. In accordance with this prediction we found that tadpoles from the northern region grew faster at relatively higher temperature than frogs in the south, whereas the opposite was true at relatively lower temperatures. North tadpoles also had a higher mortality and poorer physiological performance than south tadpoles at low temperatures. In summary, our results conclusively support the hypothesis that frogs in the north are adapted to relatively warmer developmental conditions than frogs in the south.
Origins of clonal diversity in the hypervariable asexual ostracode Cypridopsis vidua
Authors: Cywinska A. , Hebert P. D. N.
Published: March 2003

Prior allozyme studies have indicated that populations of the asexual ostracode, Cypridopsis vidua (Müller), show extraordinary clonal diversity. Based on a joint examination of allozyme variation and sequence divergence at the mitochondrial cytochrome c oxidase I (COI) gene, the present analysis provides new insights concerning the origins of this variation. The results establish that populations of C. vidua in one recently deglaciated region of North America are not only allozymically diverse, but also include several divergent mitochondrial DNA (mtDNA) lineages. The extent of sequence divergence among these lineages is so large as to suggest their diversification over the past 7–8 million years. The patterning of genetic divergence among co-occurring clones makes it apparent that much of the mtDNA and allozyme diversity in local populations owes its origins to recurrent colonization events. However, in situ mutational diversification also appears to explain some variation. The mechanisms enabling the sustained coexistence of such a large array of closely allied genotypes remain unclear, but there is an apparent difference in equilibrium diversity between benthic and planktonic asexual organisms.
A test of the Darwin–Fisher theory for the evolution of male secondary sexual traits in monogamous birds
Authors: Dearborn D. C. , Ryan M. J.
Published: March 2003

The Darwin–Fisher theory proposes that the presence of male secondary sexual traits in monogamous birds is selected for by early season breeding of females that are in good condition. These early breeding females have high fecundity because of their good condition, and they select mates based on secondary sex traits. We tested whether this hypothesis may be responsible for the presence of male sexual ornaments in the great frigatebird, a socially and genetically monogamous seabird. Consistent with the Darwin–Fisher theory, we found that reproductive success declined over the season. However, males with more exaggerated ornaments were not chosen as mates earlier in the season than males with less exaggerated ornaments, and selection gradients on these ornaments were not significantly different from zero.
Paternity analysis in Ophiopogon xylorrhizus Wang et Tai (Liliaceae s.l.): selfing assures reproductive success
Authors: He T. , Smouse P. E.
Published: March 2003

We assessed the utility of codominant allozyme markers for paternity analysis in natural populations of Ophiopogon xylorrhizus (Liliaceae s. l.) by means of likelihood-based approach. In the three independent natural stands of 46 individual plants with 354 seeds of O. xylorrhizus (Liliaceae s. l), we assigned 319 seeds to a single individual with the highest LOD score. Among these, 179 seeds had a significant D-value. An individual (acting either as female or male) mateds with an average of one other individual on average to reproduce, except when it self-pollinated. If an individual that neither donated pollen to other individuals nor selfed, being strictly a pollen acceptor, the number of offspring produced was half that produced by as many offspring as individuals which both provided and accepted pollen (4.1 vs. 9.5). Significant positive relationships were found in all the three stands between the number of self-pollen an individual produced and the number of seeds that individual set. Male outcrossing reproductive success was unevenly varied, both in amount and spatial location. The individuals located in the centre of the stand and the individuals closest to each other had higher male outcrossing reproductive success than those at the edge of the stand. Male selfing reproductive success showed a similar pattern, with an even distribution of female reproductive output. Most mating events were took place within 20 m. The distance between mates mirrored the active ranges of pollinators, and shaped the fine-scale population spatial genetic spatial structure. The results indicate that selfing assures reproductive success in O. xylorrhizus.
Developmental stability and genetic architecture: a comparison within and across thermal regimes in tadpoles
Authors: Olsson M. , Uller T.
Published: March 2003

We investigated homogeneity of growth and development as indices of developmental stability in sibling tadpoles from two sampling regions of the common frog, Rana temporaria. One region is characterized by relatively warm breeding ponds with a short activity season (`north'), and one by relatively cool breeding ponds and a long activity season (`south'). Tadpoles from the two regions were raised in three different temperatures selected to mimic the natural variation throughout the range. The results show that (1) north tadpoles respond with a relatively greater increase in growth with increased temperature than south tadpoles, (2) mean growth rate and its coefficient of variation were negatively correlated in the temperature regime in which a population was primarily under selection in the wild, whereas no such correlation was found at temperatures more seldom encountered in the natural populations, (3) phenotypic and genetic correlations between morphological traits within individuals were positive and were relatively higher in north than south tadpoles in the warm treatment, but higher for south tadpoles in the cold treatment and (4) across thermal environments, south tadpoles showed significant genetic correlations, whereas the correlations for north tadpoles were not significantly different from zero. South tadpoles showed only positive genetic correlations (n=30), whereas 14 of 30 correlation coefficients were negative in north tadpoles. In conclusion, developmental stability for growth and morphometry was higher at `optimal' conditions and decreased at the tail ends of the reaction norms within regions, with marked differences reflecting selection history between regions.
Physiological consequences of immune response by Drosophila melanogaster (Diptera: Drosophilidae) against the parasitoid Asobara tabida (Hymenoptera: Braconidae)
Authors: Hoang A.
Published: March 2003

Parasites can exert a wide range of negative effects on their hosts. Consequently, hosts that can resist infection should have a selective advantage over nonresistant conspecifics. Yet, host populations remain susceptible to some parasites. Could genetic heterogeneity in the host's ability to resist parasites reflect costs of mounting an immune response? Previous work on Drosophila melanogaster establishes that maintaining the ability to mount an immune response decreases larval competitive ability. Moreover, mounting an immune response decreases fitness.  I report on the impact of mounting an immune response on fitness of D. melanogaster survived parasitism by Asobara tabida. I used isofemale lines to determine whether genotype influences the costs of immune response. I examined fitness consequences both to larvae and adults. Survivors of parasitism show no measurable decrease in larval fitness (development time) but have decreased adult fitness (population growth rates), probably because of their smaller size.
A genotypic trade-off between the number and size of clonal offspring in the stoloniferous herb Potentilla reptans
Authors: Stuefer J. F. , Van Hulzen J.B. , During H. J.
Published: March 2003

A negative, genetic correlation between the total number and average size of progeny is a classical life-history trade-off that can greatly affect the fitness of organisms in their natural environments. This trade-off has been investigated for animals and for sexually reproducing plants. However, evidence for a genetical size-number trade-off for clonal progeny in plants is still scarce. This study provides experimental evidence for such a trade-off in the stoloniferous herb Potentilla reptans, and it studies phenotypic plasticity to light availability for the involved traits. Genotypes of P. reptans were collected from distinctively different environments, clonally replicated and exposed to high light and to shaded conditions. We found a significant negative correlation between the average size and the total number of offspring across genotypes for both light environments. Shading reduced ramet numbers, but hardly affected average ramet size.
Human longevity and early reproduction in pre-industrial Sami populations
Authors: Helle S. , Käär P. , Jokela J.
Published: March 2003

Senescence is predicted to be associated with the intensity and timing of reproduction at an earlier age. Here, we examine the phenotypic association between reproduction and post-reproductive survival in three pre-industrial human populations that lived in Northern Scandinavia during 1640–1870. In both sexes longevity was independent of the total number of born or adult children, whereas early reproduction was negatively associated with the longevity of females and males. Our results thus do not support the view that reproductive investment as such has a negative impact on longevity, but suggest that survival costs are associated with the scheduling of reproduction. We discuss, however, an alternative point of view suggesting that less intense selection for early reproduction, extended parental care, and social structure allowing kin selection through the effects of close relatives are factors that have selected for the long post-reproductive life span in humans.
Timing of the population dynamics of bullhead Cottus gobio (Teleostei: Cottidae) during the Pleistocene
Authors: Volckaert F. A. M. , Hänfling B. , Hellemans B. , Carvalho G. R.
Published: March 2003

Pleistocene genetic structure of the bullhead, Cottus gobio, was evaluated across the western Palearctic using a 771-bp long fragment of the mitochondrial control region in 123 individuals collected at 35 sites (data set I). In total, 59 haplotypes that differed at 73 positions (9.3%) were detected. Data analysis also included sequences from Englbrecht et al. (2000), thus increasing the sampling to a more comprehensive data set of 529 fish and 63 control region sequences of 482 bp (data set II). A minimum spanning and phylogenetic tree identified a seventh clade (Brittany–Loire) in addition to the previously identified six clades. The geographical range of the North Sea and Lower Rhine clades was considerably larger than thought previously. Haplotype diversity was generally low, and the total fixation index high (FST  = 0.49). Among-group differentiation accounted for 41.7% (data set I) of the variation. Contiguous range expansions and restricted gene flow combined with isolation by distance, interspersed with past fragmentation characterize bullhead across its range. New is the knowledge that dated interglacial periods correlated with population expansions; river captures, proglacial lake systems and sea level played a significant role in the dispersal and expansion either in northern or southern direction. Hence it became possible to identify and date the colonization routes and putative palaeorefugia, most of which were located in Central and North-west Europe. Glacial periods resulted in distinct fragmentation events and lineage sorting.
Tempo and mode in evolution: phylogenetic inertia, adaptation and comparative methods
Authors: Blomberg S. P. , Garland T.
Published: March 2003

Before the Evolutionary Synthesis, ‘phylogenetic inertia’ was associated with theories of orthogenesis, which claimed that organisms possessed an endogenous perfecting principle. The concept in the modern literature dates to Simpson (1944), who used ‘evolutionary inertia’ as a description of pattern in the fossil record. Wilson (1975) used ‘phylogenetic inertia’ to describe population-level or organismal properties that can affect the course of evolution in response to selection. Many current authors now view phylogenetic inertia as an alternative hypothesis to adaptation by natural selection when attempting to explain interspecific variation, covariation or lack thereof in phenotypic traits. Some phylogenetic comparative methods have been claimed to allow quantification and testing of phylogenetic inertia. Although some existing methods do allow valid tests of whether related species tend to resemble each other, which we term ‘phylogenetic signal’, this is simply pattern recognition and does not imply any underlying process. Moreover, comparative data sets generally do not include information that would allow rigorous inferences concerning causal processes underlying such patterns. The concept of phylogenetic inertia needs to be defined and studied with as much care as ‘adaptation’.
Proximate mechanisms of variation in the carotenoid-based plumage coloration of nestling great tits (Parus major L.)
Authors: Tschirren B. , Fitze P. S. , Richner H.
Published: March 2003

Many vertebrates use carotenoid-based signals in social or sexual interactions. Honest signalling via carotenoids implies some limitation of carotenoid-based colour expression among phenotypes in the wild, and at least five limiting proximate mechanisms have been hypothesized. Limitation may arise by carotenoid-availability, genetic constraints, body condition, parasites, or detrimental effects of carotenoids. An understanding of the relative importance of the five mechanisms is relevant in the context of natural and sexual selection acting on signal evolution. In an experimental field study with carotenoid supplementation, simultaneous cross-fostering, manipulation of brood size and ectoparasite load, we investigated the relative importance of these mechanisms for the variation in carotenoid-based coloration of nestling great tits (Parus major). Carotenoid-based plumage coloration was significantly related to genetic origin of nestlings, and was enhanced both in carotenoid-supplemented nestlings, and nestlings raised in reduced broods. We found a tendency for ectoparasite-induced limitation of colour expression and no evidence for detrimental effects of carotenoids on growth pattern, mortality and recruitment of nestlings to the local breeding population. Thus, three of the five proposed mechanisms can generate individual variation in the expression of carotenoid-based plumage coloration in the wild and thus could maintain honesty in a trait potentially used for signalling of individual quality.
Effectiveness of a protocol to improve transfusion practice in knee replacement surgery
Authors: Boralessa H. , Boralessa H. , Contreras M. , Lang‐Stevenson A. , DeSilva A.
Published: March 2003

Background and Objectives

The available guidelines on red cell transfusion are not clearly defined and therefore have had only a modest impact on transfusion practice. The aims of this study were to assess the rate of compliance with a transfusion algorithm and its effect on transfusion practice.

Materials and Methods

A prospective observational study was carried out on 101 patients who underwent primary elective total knee replacement surgery.

Results

Only 30% of the patients were transfused. An overall compliance rate of 77% was achieved with the transfusion algorithm.

Conclusion

A transfusion algorithm, together with staff education, is effective in reducing both the number of patients transfused and inappropriate transfusions.
Resuscitation fluids
Authors: Grocott M. P. W. , Hamilton M. A.
Published: March 2003

Background and Objectives The aim of this review was to summarize the properties of the commonly available resuscitation fluids and highlight where knowledge of the characteristics of individual fluids might guide their use in clinical practice. Some of the current controversies surrounding resuscitation fluids are also discussed. Blood or blood products, or strategies of fluid administration, are not focused upon.

Conclusions The clinical trial data does not support the concept of a therapeutic advantage for either crystalloids or colloids, despite claimed theoretical advantages for both classes of fluid. The available colloid solutions have quite distinct profiles of activity, both in terms of their plasma volume expansion profile and other physiological and pharmacological properties. Recent data suggests that physiologically balanced crystalloid and colloid solutions may improve clinical outcomes when compared with saline‐based fluids.
Increased non‐transferrin bound iron in plasma‐depleted SAG‐M red blood cell units
Authors: Marwah S. S. , Blann A. , Harrison P. , Lumley M. A. , Wright J. , McDowell J. , Phillips J. D. , Rea C. , Bareford D.
Published: March 2003

Background and Objectives Non‐transferrin bound iron (NTBI) is associated with increased morbidity in a number of transfusion‐dependent disease states such as the severe haemoglobinopathies. We hypothesized that this may be related to excess NTBI present in plasma‐depleted red blood cell units that are free of clear haemolysis.

Materials and Methods The level of NTBI was determined using the bleomycin assay in samples from 20 stored plasma‐depleted red cell units, at approximate 5‐day intervals up to day 33 after donation. Forty units of fresh‐frozen plasma (FFP) and 40 units of platelet concentrates were used as negative controls, and samples from 12 units of FFP were also serially assessed.

Results Median [interquartile range (IQR)] NTBI was 0 µm (0–0·35) in samples taken from units 3–10 days after donation. Thereafter, the levels of NTBI increased, becoming significant (median 3·05; IQR: 0·05–6·7 µm) 17–22 days after donation. After 30 days, NTBI was detectable in all red cell units. NTBI was undetectable in platelet concentrates and FFP.

Conclusions Increased levels of NTBI become detectable 17–22 days after donation and increase further with storage time. This excess NTBI may promote bacterial infection in iron‐loaded individuals.
A novel true volumetric method for the determination of residual leucocytes in blood components
Authors: Cassens U. , Greve B. , Tapernon K. , Nave B. , Severin E. , Sibrowski W. , Göhde W.
Published: March 2003

Background and Objectives Accurate determination of residual leucocytes [white blood cells (WBC)] in blood components is of high clinical importance. To date, several labour‐intensive, time‐consuming or expensive techniques have been used for this purpose.

Materials and Methods A method for the determination of residual WBC is described using a novel low‐cost flow‐cytometric cell counter and analyser (CCA). The DNA in WBC was stained using 4′‐6‐diamidino‐2‐phenylindole (DAPI) and WBC were automatically analysed by true volumetric counting of 200‐µl samples (prepared from a 20‐µl undiluted sample).

Results Dilution experiments over a range of 0·5–50 WBC/µl showed a linearity of r= 0·998. The detection limit of this method was 0·83 WBC/µl of red blood cell concentrate (RCC) and 0·67 WBC/µl of platelet concentrate (PC), with an accuracy of 95·5%.

Conclusion Residual WBC (< 1 WBC/µl) can be accurately counted using the CCA within 2 min and at a total cost of less than € 1 per sample.
Polymorphism of the TT virus and its frequency in Polish blood donors
Authors: Grabarczyk P. , Brojer E.
Published: March 2003

Objective To determine, in Polish blood donors, the frequency of TT virus (TTV) using different primers and the sequence diversity of TTV genotypes.

Materials and Methods Two‐hundred blood donors were studied. TTV DNA was detected by the polymerase chain reaction (PCR) using primers for the coding (ORF1) and non‐coding (NC) regions. Twenty isolates were genotyped by sequencing the ORF1 fragment.

Results TTV DNA was detected in 78% of donors using NC primers and in 10% using ORF1 primers. The frequency of TTV DNA detection by NC primers was observed to increase with donor age, whereas the frequency of detection by ORF primers did not differ between various age‐groups. The nucleotide sequence homology of Polish TTV isolates ranged from 59 to 99%. Three genotypes (1b, 2b and 2c) were identified.

Conclusions The frequency of TTV detection depends on the primers used for the PCR. Using the NC primers the virus is detected in the majority of donors, whereas the ORF1 primers strongly underestimate the prevalence of TTV. The frequency of TTV DNA increases with age. Polish TTV isolates are highly polymorphic and are classified as 1b, 2b and 2c.
Value of central analysis of leucocyte depletion quality control data within the National Blood Service, England
Authors: Beckman N. , Cardigan R. , Wallington T. , Williamson L. M.
Published: March 2003

Background and Objectives The results of quality monitoring leucocyte counts were analysed nationally for the first 2 years of universal leucocyte depletion (LD), spanning the time‐period before and after standardization of the counting and LD methods. The objectives were twofold: first to determine whether the implementation strategy was effective in achieving the LD specification (< 5 × 106 leucocytes in 99% of components with 95% statistical confidence); and second, whether quality monitoring was able to detect potential non‐conformance.

Materials and Methods Residual leucocytes were counted using Beckman Coulter or Becton Dickinson (BD) flow cytometers and reagents. Data were collected into standardized analysis software (NWA Quality Analyst) for local trend analysis and checks for conformance to process specification, and collated centrally. Analysis was performed for six time‐periods between January 1999 and March 2001. Specification failures were analysed to determine the likelihood of extreme failure. Statistical process monitoring was adjusted to suit LD processes.

Results Data from red cells in optimal additive solution (OAS), filtered either as whole blood or red cell concentrates, and platelet pools improved significantly over the 2‐year period with specification failures falling from 0·35%, 0·48% and 0·56%, respectively, in January–June 1999 to 0·06%, 0·01% and 0·04% in January–March 2001. Specification failures in red cells in OAS LD for the period January–December 2000 showed only 0·02% with a leucocyte count of > 30 × 106/unit. Extreme failures are now very rare. Monitoring methods have been effective in detecting process change and drift.

Conclusion LD performance varies between different LD systems, but monitoring has proved sufficiently robust to detect processes that perform poorly. The chosen specification has been both achievable and appropriate to the systems in use. Standardization of the counting method is central to the ability to monitor and analyse results effectively across the whole service.
A single window‐period donation detected by human immunodeficiency virus p24 antigen after 5 years of routine screening in a group of Brazilian blood banks
Authors: Wendel S. , Fachini R. M. , Levi J. E. , Ghaname J. N. , Mendonça M. C. , De Almeida Neto C. , De Carvalho Braga M. , Di Pietro & A. E.
Published: March 2003

Background and Objectives The purpose of this article was to describe the experience of screening for human immunodeficiency virus (HIV) p24 antigen (p24Ag) in blood donors, in four Brazilian Blood Banks, and to report the detection of the first window‐period donation.

Materials and Methods During 61 months (May 96 to June 01), 103 470 consecutive donations were screened for HIV p24Ag using commercially available enzyme‐linked immunosorbent assay (ELISA) kits. Testing was carried out in accordance with the instructions supplied with the kits.

Results Fifty‐eight repeatedly reactive samples were identified [0.056% of the total; 95% confidence interval (95% CI): 0·042–0·070]. Ten of the 58 were confirmed as p24Ag positive after neutralization (0·010%; 95% CI: 0·004–0·016), nine of the 10 (0·009%; 95% CI: 0·003–0·014) were also HIV antibody positive and only one (0·001%; 95% CI: 0–0·003) was HIV antibody negative.

Conclusions In this setting the rate of sole p24Ag‐positive donations was one in 103 740. This figure corresponds closely with the previously estimated yield of one in 87 796 donations. The yield of HIV p24Ag+ : Ab− has been previously estimated in our centres to be 1 : 87 796 donations, a value similar to that observed in actual practice.
Prevalence of illicit drug use in plasmapheresis donors
Authors: Peters F. T. , Maurer H. H. , Hellstern P.
Published: March 2003

Background and Objectives No data are presently available concerning the frequency of illicit drug use in plasmapheresis donors. We therefore examined source plasma units produced in the United States (US) and in Germany for evidence of illicit drug use among donors.

Materials and Methods Seventy‐five US plasma units from 10 different US states and 75 German plasma units that had been analysed principally for their protein composition were screened for drugs. Determinations were made, using automated immunoassays, of the presence of cannabis, cocaine, amphetamine, methamphetamine, methylenedioxymethamphetamine (MDMA), methylenedioxyethylamphetamine (MDE) and opiates. Positive results were confirmed by gas chromatography–mass spectrometry.

Results Eleven US plasma units were found to be positive for cocaine (14·6%), whereas all German samples were cocaine negative (P = 0·0007). Fifteen US plasma units (20%) and one German unit (1·3%) were confirmed as positive for cannabis (P = 0·0003). Three out of 75 US plasma units were positive for both cannabis and cocaine. In none of the 150 samples were amphetamine, methamphetamine, MDMA, MDE or opiates detected.

Conclusions Our results strongly suggest differences in cocaine and cannabis consumption between US and German plasmapheresis donors. If these results are confirmed by larger‐scale studies, random drug screening (including cocaine) of donors should be implemented in order to reduce the number of drug‐containing plasma units, especially in the USA.
Indirect oscillometric and direct blood pressure measurements in anesthetized and conscious neonatal foals
Authors: Nout Yvette S. , Corley Kevin T.T. , Donaldson Lydia L. , Furr Martin O.
Published: March 2003

Objective:To investigate the agreement between indirect oscillometric and direct blood pressure measurement in the equine neonate.

Design:Prospective observational study.

Setting:University Veterinary Teaching Hospital.

Animals:Ten crossbred foals of 30–46 hours of age.

Interventions:Six animals (Group 1) were anesthetized. Four animals (Group 2) were restrained on a mat. All animals were instrumented with a catheter in the greater metatarsal artery and an oscillometric blood pressure cuff over the coccygeal artery. Blood pressure was varied with dobutamine, phenylephrine, nitroprusside, and increased depth of anesthesia (Group 1) or dopamine (Group 2).

Measurements and main results:Simultaneous direct and indirect blood pressure measurements were obtained from the greater metatarsal artery and the coccygeal artery, respectively. There was good agreement between the 2 methods for mean and diastolic blood pressures in both groups, but not for systolic pressure. The agreement was best in mean blood pressure of anesthetized foals (mean bias –1.07; limits of agreement – 9.39, 7.25 mmHg).

Conclusions:Indirect oscillometry appears to be an acceptable method for measuring mean arterial blood pressure in both anesthetized and conscious neonatal foals, and may be a valid method of monitoring critically ill foals.
Going 24/7: when it is time to make the leap and assume the associated challenges
Authors: Catanzaro Thomas E.
Published: March 2003

Some veterinary practices are looking at expanding hours to grab more market share or to allow their overheads to be spread over more income transactions. But there are some basic premises that need to be assessed before jumping into the fray. First of all, there is a difference between an Urgent‐Care facility and an Emergency Practice. There are working hours for doctors and staff to be considered as well as economic trade‐offs. Community demographics, equipment needed and training are the other issues to be considered. There is more to it than to just increased access.
Haarausfall vom weiblichen Typ
Authors: Birch M. P. , Lalla S. C. , Messenger A. G.
Published: March 2003

Zusammenfassung: Haarausfall vom weiblichen Typ ist häufig und durch eine Reduktion der Haardichte im Bereich des Scheitels und der vorderen Kopfhaut bei Erhalt des Haaransatzes gekennzeichnet. Mit höherem Lebensalter steigt die Prävalenz. Im Allgemeinen wird diese Form des Effluviums als weibliches Pendant der männlichen Glatzenbildung betrachtet und auch als weibliche androgenetische Alopezie bezeichnet. Allerdings ist die Bedeutung der Androgene nicht vollständig geklärt. Ohne Zweifel kann der Verlust der Kopfhaare ein Merkmal von Hyperandrogenismus bei Frauen sein, doch findet man bei vielen Frauen mit einem Haarausfall vom weiblichen Typ keine anderen klinischen oder biochemischen Hinweise für einen Androgenüberschuss. Haarausfall vom weiblichen Typ ist wahrscheinlich ein multifaktorielles, genetisch determiniertes Geschehen, und es ist möglich, dass sowohl Androgen‐abhängige und Androgen‐unabhängige Mechanismen zum Phänotyp beitragen. Im Umgang mit Patientinnen, die unter Haarausfall vom weiblichen Typ leiden, muss der Arzt sich immer bewusst sein, dass die unerwünschten Wirkungen auf die Lebensqualität als sehr gravierend empfunden werden können und nicht unbedingt mit dem tatsächlichen Haarverlust korrelieren müssen. Die gegenwärtig verfügbaren Behandlungsoptionen sind im Prinzip unbefriedigend, bewirken aber bei einigen Frauen durchaus eine leichte Verbesserung der Haardichte.
Osmotically Primed Seed and Seedling Reactions to Variations in Day/Night Temperature
Authors: Al‐Mudaris M. A. , Jutzi S. C.
Published: March 2003

The effects of alternating day/night temperatures, varying in maxima and minima but all averaging 30 °C, on germination and seedling characteristics of Sorghum bicolor L. (Moench) were investigated. Seeds of sorghum CSV 15 were soaked in 2, 4 or 6 g NaCl l−1 solutions for 2 days at 25 °C, soaked in water for 1 day at 25 °C, or untreated. After treatment, drying and storage, seeds were germinated at 30/30 (day/night), 35/25, 40/20 or 41/19 °C temperature regimes under a polyethylene glycol‐induced drought level of −3 bar. Results revealed no advancement of germination percentage but a partial increase in germination speed by osmotic seed treatments. All three osmotic treatments also reduced the plumule/radicle ratio owing to a speculated increase in root over shoot growth. Temperature regimes significantly influenced both germination and seedling characteristics with the optimum temperature appearing to be 35/25 °C. Increasing the temperature amplitude from 30/30 to 35/25 °C increased germination speed, which was reduced by incremental increases in temperature amplitude to 40/20 or 41/19 °C.
Investigation of Factors Determining Genotypic Differences in Seed Yield of Non‐irrigated and Irrigated Chickpeas Using a Physiological Model of Yield Determination
Authors: Krishnamurthy L. , Johansen C. , Sethi S. C.
Published: March 2003

Physiological attributes determining yield, both under drought and under irrigated conditions, of some advanced chickpea lines of recent origin were investigated over two seasons using a physiological model. Total shoot biomass, grain yield, and vegetative (Dv) and reproductive (Dr) durations were measured and the crop growth rates (C) and the rate of partitioning to seed (p) were estimated. The contribution of model parameters to variations in grain yield were determined by path analysis, and the relationships of the yield determinants with seed yield were obtained by regression techniques. The model was found to be suitable for chickpea, and when the parameters were fitted the model explained 98% of the variation. Irrigation enhanced Dr and C. While C was the major single yield determinant, the combination of C and p in non‐irrigated environments explained most of the grain yield variation. Dv and Dr exhibited a negative relationship while C and p exhibited a positive relationship under drought stress and a negative relationship in the irrigated environment. There were indications of the existence of an optimum Dv for maximum C among the genotypes, suggesting the need to select for optimum duration genotypes. As high values for p and C in severe drought stress and Dr and C in the irrigated environments are advantageous for high yield, separate breeding strategies are needed for different soil water environments.
Effects of Irrigation at Different Growth Stages on Vegetative Growth of Mung Bean, Vigna Radiata (L.) Wilczek, in Dry and Intermediate Zones of Sri Lanka
Authors: De Costa W. A. J. M. , Shanmugathasan K. N.
Published: March 2003

Mung bean crops in the subhumid zones of Sri Lanka experience significant drought periods. The objective of this study was to quantify the growth response of mung bean to irrigation at different phenological stages and thereby determine the optimum irrigation regime to maximize growth. Four field experiments were conducted at two sites in 1995 and 1996. The crop duration of mung bean was divided into three stages: vegetative (from germination to appearance of first flower), flowering (from appearance of first flower to 75 % pod initiation) and pod‐filling (from 75 % pod initiation to maturity). Eight treatments were devised to represent all possible combinations of irrigation at the three stages. Maximum leaf area index (ranging from 0.6 to 2.6 across treatments) and total leaf area duration were increased significantly by irrigation during the vegetative stage. Specific leaf weight decreased and maximum total crop biomass (150–400 g m−2) increased with the number of stages irrigated. Irrigation decreased the absolute root biomass and increased the shoot:root ratio. It is concluded that, in this agroclimatic zone of Sri Lanka, irrigation of mung bean during the vegetative stage is critical for maximizing leaf area. However, biomass production can be maximized by increasing the number of stages irrigated irrespective of irrigation at any specific stage.
The Effect of Intercropping Lablab purpureus L. with Sorghum on Yield and Chemical Composition of Fodder
Authors: Shehu Y. , Alhassan W. S. , Pal U. R. , Phillips C. J. C.
Published: March 2003

In two years the growth and composition of mixtures of sorghum with Lablab purpureus as strips, paired rows and alternate rows were compared with those of sorghum and lablab monocrops. In the first year, when sowing did not occur until 7 August, the sorghum yields were low in the monocrop and even less in the mixed crops. Lablab yield was also reduced in mixtures compared with the monocrop, but total forage yield was greater for the mixed crops compared with sorghum alone. Of the mixed cropping systems, a reduction in the yield of lablab plants and in the phosphorus and potassium content of shed lablab leaves in paired rows suggested that there was more competition for nutrients between lablab plants grown in this treatment. In the second year, earlier sowing increased sorghum growth at the expense of lablab yield in the mixed cropping systems, with the result that total forage yield was not increased when sorghum was intercropped with lablab. However, the crude protein content of sorghum stems and leaf yield were increased in mixed crops, particularly in paired and alternate rows rather than strips, demonstrating that close configuration of the legume and cereal are necessary for the cereal to obtain most benefit from nitrogen fixed by the legume. It is concluded that, when conditions are favourable for rapid sorghum and lablab growth, the sorghum will benefit more when it is grown in paired rows with lablab rather than in strips. However, the close spacing normally adopted for paired rows may encourage competition between lablab plants and increase the requirements for phosphorus and potassium fertilizer.
Relationship between Water Content and Growth of Seed and Fibre of Three Cotton Genotypes
Authors: Rabadia V. S. , Thaker V. S. , Singh Y. D.
Published: March 2003

Three cotton genotypes (varying in their final seed size), viz. H‐6 and H‐4 (Gossypium hirsutum L.) and V‐797 (Gossypium herbaceum L.) were studied for their growth kinetics of seed and fibre. Both biphasic linear and polynomial models were used to demark different phases of cotton seed growth. The polynomial model appeared to be appropriate to define the growth phases of cotton seed as compared to the linear model. The rate and the duration of dry matter accumulation were obtained by differentiating the best‐fit polynomial equations. Based on the data of dry weight and water content, cotton seed development is divided into four different phases, viz. (a) cell division, (b) cell elongation, (c) dry matter accumulation and (d) maturation. The rate of dry matter accumulation showed a close correlation with water content of seed as well as of the fibre, in all three genotypes studied. It is proposed that water content of seed or fibre plays an important role in determining dry weight of three genotypes.
Mineral Nitrogen Availability and Isoflavonoid Accumulation in the Root Systems of Soybean (Glycine max (L.) Merr.)
Authors: Zhang F. , Maáce F. , Smith D. L.
Published: March 2003

Isoflavonoids, as plant‐to‐bacteria signal molecules, play an important role in the establishment of the soybean (Glycine max (L.) Merr.)–Bradyrhizobium japonicum nitrogen (N) fixing symbiosis. They are essential to the development of effective root nodules and responsible for inducing the nod genes of B. japonicum. Because N affects a broad range of infection events, especially the symbiotic events occurring within 18 h of inoculation, it is reasonable to hypothesize that mineral N disrupts the interorganismal signal exchange between soybean host plants and B. japonicum. High performance liquid chromatographic (HPLC) analysis of root extracts of soybean, inoculated with B. japonicum or not, grown with various levels of mineral N in the rooting medium were performed to test this hypothesis. The results of these studies indicated that: (1) at early plant growth stages (before the onset of N fixation), a strong negative relationship between N application and soybean root isoflavonoid (genistein and daidzein) concentrations existed; (2) although isoflavonoid (genistein and daidzein) concentrations in both inoculated and non‐inoculated soybean root systems were generally decreased by N application, at very low N levels (10 mg N l−1) genistein in the non‐inoculated plant roots was not decreased relative to the 0 N plants; (3) averaged over all mineral N treatment levels and sampling times, inoculation of soybean with B. japonicum increased root daidzein concentrations (P > 0.05), but did not affect genistein. Overall, N application reduced the isoflavonoid concentration of soybean root systems, which probably plays a part in the regulation of soybean nodule formation by available N.
Effects of Fungicide on Grain Yield of Barley Grown in Different Cropping Systems
Authors: Yang J. P. , Sieling K. , Hanus H.
Published: March 2003

The effect of fungicides and their combination on yield of barley under different nitrogen, slurry and tillage treatments was investigated at Hohenschulen Experimental Station near Kiel, Germany in 1991–97. Various fungicide treatments (no fungicide, and treatment with stem, leaf and ear fungicides and combinations of these), two nitrogen levels (120 and 240 kg N ha−1), two tillage systems (minimum and conventional tillage) and four slurry applications (no application, and autumn, spring and autumn plus spring applications) were used. On average, fungicide application increased barley yield by 1.1 t ha−1. The fungicide treatments could be classified into four types: (1) fungicides against stem diseases, which slightly increased yield by 0.25 t ha−1, very similar to the results for the untreated control; (2) leaf fungicides and ear fungicides applied separately, and fungicides against a combination of stem and leaf diseases, which increased yield by 1.0 t ha−1 on average; (3) fungicides against a combination of ear and stem diseases, which increased the yield by 1.22 t ha−1, and (4) fungicides against a combination of leaf and ear diseases and a combination of stem, leaf and ear diseases, which increased yield by 1.59 t ha−1 on average. The effects of fungicide on the yield were modified by crop husbandry. It can be concluded that application of fungicides against a combination of leaf and ear diseases could increase barley yield and reduce yield variation.
Saline Drainage Water, Irrigation Frequency and Crop Species Effects on Some Physical Properties of Soils
Authors: Al‐Nabulsi Y. A.
Published: March 2003

This field study evaluated the effects of water quality, irrigation frequency and crop species on some physical properties of soils. The experiment had a split‐split‐plot design, with three irrigation water qualities (normal water, drainage water and a 1 : 1 mixture of freshwater and drainage water) as the main treatments, two irrigation frequencies (at 7‐ and 14‐day intervals) as the subtreatments and two crops (barley and alfalfa) as the subsubtreatments. The soil infiltration rate was highest in the barley plot receiving freshwater irrigation at weekly intervals. The lowest soil infiltration rate was found in alfalfa plots receiving saline irrigation water at 14‐day intervals. Bulk density and proportions of micropores [pore radius (r) < 1.4 µm] were higher and the proportion of macropores (r > 14.4 µm) was lower in barley than in alfalfa. Saline irrigation caused the greatest decrease in total porosity. The soil infiltration rate was higher with more frequent irrigation, and was highest in alfalfa plots receiving freshwater irrigation. The decrease in soil bulk density and infiltration rate was greater with saline drainage water, irrespective of the crop grown and the irrigation frequency.