bluuebunny/crossref_metadata_2025 huggingface dataset:
What controls haploid—diploid ratio in the red alga, Gracilaria verrucosa?
Authors: Destombe Christophe , Valero Myriam , Vernet Philippe , Couvet Denis
Published: March 2003

The conditions for maintenance of a haploid—diploid life cycle in the species Gracilaria verrucosa were studied. This species is a red alga, where haploid plants have separate sexes. In the two natural populations studied, male and female haploid individuals were in equal proportions, and the frequency of diploid individuals reached 0.5.

A two‐fold advantage in viability for diploid relative to haploid juveniles was observed in the field. This advantage can account for a frequency of 0.5 of diploid individuals in natural populations. Different types of anomalies in the reproduction of diploid individuals were observed, all of which lead to a reduction of the haploid stage.
Hybridization between Pied and Collared Flycatchers—sexual selection and speciation theory
Authors: Alatalo Rauno V. , Eriksson Dag , Gustafsson Lars , Lundberg Arne
Published: March 2003

The Pied Flycatcher Ficedula hypoleuca and the Collared Flycatcher F. albicollis hybridize frequently on the islands of Gotland and Öland in the Baltic. Hybrids have highly reduced fertility, but introgression is likely to occur. Mating is incompletely species‐assortative and mixed pairs are common. In Central Europe, Pied Flycatcher males are brown in areas of sympatry, and thus have less resemblance to the black Collared Flycatcher males. It has been suggested that females could use male colour to increase the probability of assortative mating, and hence that a speciation process by reinforcement might be taking place. However, we found no indications that the colour of male Pied Flycatchers had an influence on their risk of disassortative mating, and therefore reinforcement probably cannot explain the geographical pattern of colour variation in Pied Flycatcher males. The song and the white collar of Collared Flycatcher males are features more likely to serve in species recognition. The songs of the two species differ greatly, but in areas of sympatry, “mixed” singing by Pied Flycatcher males was common, and this is likely to increase the risk of hybridization. It seems that interactions between the two species are far more complex than predicted by the theory of speciation by reinforcement.
Remating and male‐derived nutrients in Drosophila melanogaster
Authors: Chapman Tracey , Trevitt Sara , Partridge Linda
Published: March 2003

Laboratory natural selection and environmental manipulations were used to investigate the importance of male‐derived nutrients to female Drosophila melanogaster. No evidence for the importance of such nutrients was found. Females from the same wild type base stock exposed as adults to low quality food did not show elevated fecundity or survival when they remated more frequently, and on high quality food the females showed a ‘cost of mating’ in reduced survival. Laboratory evolution on low quality food did not lead to elevated rates of remating by females; females from each selection regimen remated more frequently than one another when kept on the food type to which they had been exposed for the previous 5 years, on which they also showed higher fecundity than one another. Even under conditions of extreme nutritional stress, when females were exposed to short term (4‐day) cycle of exposure to very low and high quality food, they remated more frequently immediately after exposure to high quality food. The results of this last experiment suggested that, under these circumstances, current nutrition, fecundity or rate of sperm usage was more important than number of sperm in store or cumulative fecundity in determining the probability that a female would remate.
A correlated response of a parasite’s virulence and life cycle to selection on its host’s life history
Authors: Koella  , Agnew
Published: March 2003

We demonstrate a correlated response of the virulence and the mode of transmission of the microsporidian parasite Edhazardia aedis to selection on the age at pupation of its host, the mosquito Aedes aegypti. We selected three lines of mosquitoes each for early or late pupation and exposed the larvae after zero, two and four generations of selection to a low and a high concentration of the parasite’s spores. Before selection the parasites induced a similar level of mortality in the six lines; after four generations of selection mortality was higher in the mosquitoes selected for late pupation than in those selected for early pupation. Overall, parasite-induced mortality was positively correlated with the mean age at pupation of the matching uninfected line. When they died, mosquitoes selected for early pupation harboured mostly binucleate spores, which are responsible for vertical transmission. Mosquitoes selected for late pupation were more likely to harbour uninucleate spores, which are responsible for horizontal transmission. The parasite enhanced this tendency for horizontal transmission by prolonging the larval period in the lines selected for late pupation, but not in the ones selected for early pupation. These results suggest that the genetic basis of the mosquito’s age at pupation helps to determine the parasite’s mode of transmission: parasites in rapidly developing mosquitoes are benign and transmit vertically, while parasites in slowly developing mosquitoes are virulent and transmit horizontally. Thus, as the host’s life history evolves, the parasite’s performance changes, because the host’s evolution changes the environment in which the parasite develops.
Heritability of directional and fluctuating asymmetry for mandibular characters in random-bred mice
Authors: Leamy
Published: March 2003

In bilateral characters, two kinds of asymmetries are common: fluctuating asymmetry (FA), or nondirectional variation between left and right sides, and directional asymmetry (DA), in which one side is consistently larger than the other. FA has been extensively used as a measure of developmental stability because of its presumed environmental basis whereas DA has not typically been recommended because it has been presumed to have at least some genetic basis. To test these two hypotheses, heritabilities were calculated via parent–offspring regression for both DA and FA in 10 triply measured mandible characters in random-bred mice. Midparent estimates of heritabilities of DA in the 10 characters were quite low (mean = 0.06), but significant for one character as well as the sum of the DA values over all characters (0.21). Midparent estimates of heritability of FA in the 10 characters also were low (mean = 0.03), but not significant for any individual character or the sum of the FA values over all characters. Heritabilities of developmental stability calculated from heritabilities and repeatabilities of FA in the mandible characters were higher in magnitude (mean of midparent estimates = 0.45), but all still were not statistically significant. It was concluded that both hypotheses were supported, but that genetic variation in DA was so small that the potential for DA as an indicator of developmental stability should be explored.
Assortative pairing with respect to parasite load in the beetle Timarcha maritima (Chrysomelidae)
Authors: Thomas  , Oget  , Gente  , Desmots  , Renaud
Published: March 2003

Because of their effects on host reproductive behaviour, parasites are theoretically expected to create sometimes assortative mating among hosts, with heavily parasitized individuals pairing together and lightly parasitized ones pairing among themselves. We investigated the influence of protozoan gut parasites on the pairing pattern of the chrysomelid beetle Timarcha maritima. In the field, fecundity was negatively correlated with the parasite load of females, unpaired males were significantly more heavily infected than paired ones and, among pairs, males and females were matched for parasite load. Mate choice experiments in the laboratory showed that males have some ability to avoid heavily infected partners when given the choice between two females. Male competitiveness, measured as their mobility, was also negatively correlated with parasite load. These results indicate that parasite-related assortative pairing in this beetle could result from parasitized females being less fecund and parasitized males less competitive.
Environmental dependence of inbreeding depression and purging in Drosophila melanogaster
Authors: Bijlsma  , Bundgaard  , Van Putten
Published: March 2003

Elimination or reduction of inbreeding depression by natural selection at the contributing loci (purging) has been hypothesized to effectively mitigate the negative effects of inbreeding in small isolated populations. This may, however, only be valid when the environmental conditions are relatively constant. We tested this assumption using Drosophila melanogaster as a model organism. By means of chromosome balancers, chromosomes were sampled from a wild population and their viability was estimated in both homozygous and heterozygous conditions in a favourable environment. Around 50% of the chromosomes were found to carry a lethal or sublethal mutation, which upon inbreeding would cause a considerable amount of inbreeding depression. These detrimentals were artificially purged by selecting only chromosomes that in homozygous condition had a viability comparable to that of the heterozygotes (quasi-normals), thereby removing most deleterious recessive alleles. Next, these quasi-normals were tested both for egg-to-adult viability and for total fitness under different environmental stress conditions: high-temperature stress, DDT stress, ethanol stress, and crowding. Under these altered stressful conditions, particularly for high temperature and DDT, novel recessive deleterious effects were expressed that were not apparent under control conditions. Some of these chromosomes were even found to carry lethal or near-lethal mutations under stress. Compared with heterozygotes, homozygotes showed on average 25% additional reduction in total fitness. Our results show that, except for mutations that affect fitness under all environmental conditions, inbreeding depression may be due to different loci in different environments. Hence purging of deleterious recessive alleles can be effective only for the particular environment in which the purging occurred, because additional load will become expressed under changing environmental conditions. These results not only indicate that inbreeding depression is environment dependent, but also that inbreeding depression may become more severe under changing stressful conditions. These observations have significant consequences for conservation biology.
Processes at the origin of similarities in dispersal behaviour among siblings
Authors: Massot  , Clobert
Published: March 2003

Processes which generate natal dispersal are largely unknown. This is particularly the case for the sources of differences among families. Three types of processes can generate the variability among families: genetic, prenatal and postnatal. We first tested the family resemblance of dispersal behaviour in the common lizard (Lacerta vivipara). We then experimentally investigated the role of pre- and postnatal factors in the variability of dispersal among families. From 1989 to 1992, we studied dispersal of juveniles from pregnant females captured in the field and maintained in laboratory until parturition. We manipulated the conditions of gestation to test for prenatal effects on juvenile dispersal. We tested postnatal effects by releasing siblings of the same family in contrasted environments. We also examined covariances of natal dispersal with maternal and offspring traits. The results showed that: (1) dispersal behaviour was similar among siblings, (2) determinants of offspring dispersal differed between sexes and years, (3) offspring dispersal was related to litter sex-ratio and offspring corpulence at birth, (4) postnatal conditions influenced male dispersal, (5) short-term prenatal conditions (i.e. maternal conditions during gestation) influenced juvenile dispersal, varying per year, (6) long-term prenatal conditions (i.e. maternal conditions during gestation in the previous year) could also influence juvenile dispersal (marginally significant).

Thus, several types of processes determine natal dispersal in the common lizard. Resemblance among siblings can partly be explained by both pre- and postnatal effects. The environment seems to be the major factor influencing juvenile dispersal in this species, i.e. dispersal essentially appears condition-dependent. The genetic basis of dispersal in vertebrates remains to be demonstrated by studies controlling for both prenatal and postnatal conditions.
Reproductive performance of clonal and sexual bark beetles (Coleoptera: Scolytidae) in the field
Authors: Løyning
Published: March 2003

In Ips acuminatus (Gyll.) parthenogenetic females occur together with sexual females and with sexual males upon which they depend for sperm. In a reciprocal-transplant experiment, I studied fecundity differences among parthenogenetic and sexual females from two populations that differ dramatically in the proportion of clonal females. In a second experiment, I studied competition between larvae from different mothers and between females from the two source populations. Fecundity measured by the number of eggs per egg tunnel was influenced by the ambient environment at the sites of the experiment as well as the origin of the female, and was generally higher for clonal than for sexual females at both sites. In experimental groups where larvae competed with larvae from their own population (pure treatments), the number of surviving pupae was significantly lower than in groups where females from the two source populations were mixed. The high fecundity of clonal females makes coexistence of the two types of females difficult to explain. It makes the reproductive advantage associated with clonality in I. acuminatus even higher than the two-fold difference due to asexuality per sé. The significant differences in the number of pupae in mixed vs. pure groups suggest ecological divergence between sexual and clonal females. This would make the mortality of larvae not only density dependent, but also frequency dependent, which could explain the coexistence of sexual and clonal females.
Factors influencing the composition of mixed populations of a hemiclonal hybrid and its sexual host
Authors: Hellriegel B. , Reyer H.-U.
Published: March 2003

Hemiclonal/hybridogenetic hybrids combine demographic superiority of asexuals and genetic diversity of sexuals, but their need for backcrossing with a parental species tightly couples them with this sexual host. How can systems like this persist in ecological and evolutionary time? Two discrete-time mathematical models describing the complex life cycle and mating system of hybridogenetic waterfrogs (Rana esculenta) identified four factors and their interactions as important. Although female mating preferences, in combination with differences in fecundity, determine species coexistence, differences in larval competitiveness seem to be more important for the hybrid‘s actual frequency. However, coexistence is possible even when host and hybrid are equally fecund and competitive. Dispersal and competition interact in their influence on species composition, but ecological and reproductive dispersal has opposing effects. In ecological terms our results explain the remarkable stability of observed species ratios over time within natural hybridogenetic populations, and indicate why the species composition can vary so widely between localities. In evolutionary terms they explain the old age of these and other hybridogenetic systems. They also suggest interesting consequences for other tightly coupled systems.
Sperm competition and small size advantage for males of the golden orb-web spider Nephila edulis
Authors: Schneider J. M. , Herberstein M. E. , De Crespigny F. C. , Ramamurthy S. , Elgar M. A.
Published: March 2003

Sexual selection, through female choice and/or male–male competition, has influenced the nature and direction of sexual size dimorphism in numerous species. However, few studies have examined the influence of sperm competition on size dimorphism. The orb-web spider Nephila edulis has a polygamous mating system and extreme size dimorphism. Additionally, the frequency distribution of male body size is extremely skewed with most males being small and few large. The duration of copulation, male size and sexual cannibalism have been identified as the significant factors determining patterns of sperm precedence in spiders. In double mating trials, females were assigned to three treatments: either they mated once with both males or the first or the second male was allowed to mate twice. Paternity was strongly associated with the duration of copulation, independent of mating order. Males that were allowed to mate twice not only doubled the duration of copulation but also their paternity. Small males had a clear mating advantage, they copulated longer than large males and fertilized more eggs. Males of different sizes used different tactics to mate. Large males were more likely to mate through a hole they cut into the web, whereas small males approached the female directly. Furthermore, small males usually mated at their first attempt but large males required several attempts before mating took place. There was no obvious female reaction towards males of different sizes.
Population differences in early life-history traits in grayling
Authors: Haugen T. O. , Vøllestad L. A.
Published: March 2003

In this paper we test population differences in early life-history traits in three grayling Thymallus thymallus populations. The grayling shared ancestors some 80–90 years ago. We performed common-garden experiments at three temperatures (mimicking population-specific summer temperatures), and measured survival and growth rates during early development. We found significant additive genetic variance in size (length and yolk-sac volume) measured at hatching, swim-up and termination of the experiment, and significantly different reaction norms for growth rate and survival during the period of first feeding. In general, each population did best at the temperature experienced in nature. These differences in early life-history traits suggest that natural selection has resulted in local adaptation in a time period of 13–18 generations.
Direct and indirect responses to selection on pollen size in Brassica rapa L.
Authors: Sarkissian T. S. , Harder L. D.
Published: March 2003

Pollen size varies little within angiosperm species, but differs extensively between species, suggesting the action of strong selection. Nevertheless, the potential for genetic responses of pollen size to selection, as determined by additive genetic variance and genetic correlations with other floral traits, has received little attention. To assess this potential, we subjected Brassica rapa to artificial selection for large and small pollen during three generations. This selection caused significant divergence in pollen diameter, with additive genetic effects accounting for over 30% of the observed phenotypic variation in pollen size. Such heritable genetic variation suggests that natural selection could effect evolutionary change in this trait. Selection on pollen size also elicited correlated responses in pollen number (–), flower size (+), style length (+), and ovule number (+), suggesting that pollen size cannot evolve independently. The correlated responses of pollen number, flower size and ovule number probably reflect the genetically determined and physically constrained pattern of resource allocation in B. rapa. In contrast, the positive correlation between pollen size and style length may represent a widespread gametic-phase disequilibrium in angiosperms that arises from nonrandom fertilization success of large pollen in pistils with long styles.
Role of ageing and temperature in shaping reaction norms and fecundity functions in insects
Authors: Kindlmann P. , Dixon A. F. G. , Dostálková I.
Published: March 2003

The existing energy partitioning models assume that fecundity is constant throughout adult life. In insects, however, fecundity is a triangular function of time: after maturation, it initially sharply increases and after reaching its maximum it slowly declines as the mother ages. These models also fail to explain that empirical data generally indicate an increase in juvenile growth rate caused by improvement in food quality results in larger adults, whereas that caused by an increase in ambient temperature results in smaller adults. This ‘life history puzzle’ has worried many biologists for a long time.

An energy-partitioning model for insects is presented with soma and gonads as its components, which – contrary to other models – assumes ageing of soma. This model explains the triangular shape of the fecundity function, and also offers an explanation of the ‘life history puzzle’. The differential response in adult size to changes in food quality and temperature in nature may result from the differential responses of our model’s parameters to changes in these environmental parameters. Better food quality results in bigger adults, because food quality affects the assimilation rate, but not the rate of conversion of gonadal biomass into offspring, or the rate of senescence. In contrast, an increase in temperature speeds up all the processes. That is, temperature affects the assimilation rate, the conversion rate of gonadal biomass into offspring, and the rate of senescence equally. Therefore, an increase in temperature results in larger or smaller adults, depending on the shape of the senescence function.
Costs of intersexual conflict in the isopod Idotea baltica
Authors: Jormalainen V. , Merilaita S. , Riihimäki J.
Published: March 2003

In sexual reproduction one sex can increase its reproductive success at the cost of the other, a situation known as intersexual conflict. In the marine isopod Idotea baltica, males guard females before copulation. The guarding phase is preceded by struggles as females resist males’ attempts to initiate guarding. We determined whether the struggle and/or mate-guarding result in fitness costs in the form of decreasing fecundity and lower levels of the energy storage compounds, glycogen and lipids. Females that underwent the period of struggles with males had decreased glycogen levels compared with females maintained alone. No such cost was found for males. Females guarded by a male also had smaller eggs than females that were not guarded. Thus the intersexual conflict, imposed by the fitness maximization strategy of the males, gave rise to both a fecundity cost and an energetic cost for females. The fecundity cost confirms the existence of intersexual conflict in I. baltica. This cost is shared by males, suggesting that the intersexual conflict restrains the reproductive output of both sexes.
Female remating in butterflies: interaction between female genotype and nonfertile sperm
Authors: Wedell N.
Published: March 2003

Female mating rate is fundamental to evolutionary biology as it determines the pattern of sexual selection and sexual conflict. Despite its importance, the genetic basis for female remating rate is largely unknown and has only been demonstrated in one species. In paternally investing species there is often a conflict between the sexes over female mating rate, as females remate to obtain male nutrient donations and males try to prevent female remating to ensure high fertilization success. Butterflies produce two types of sperm: fertilizing, eupyrene sperm, and large numbers of nonfertile, apyrene sperm. The function of apyrene sperm in the polyandrous, paternally investing green-veined white butterfly, Pieris napi, is to fill the female’s sperm storage organ thereby reducing her receptivity. However, there is large variation in number of apyrene sperm stored. Here, I examine the genetic basis to this variation, and if variation in number of apyrene sperm stored is related to females’ remating rate. The number of apyrene sperm stored at the time of remating has a genetic component and is correlated with female remating tendency, whereas no such relationship is found for fertilizing sperm. The duration of the nonreceptivity period in P. napi also has a genetic component and is inversely related to the degree of polyandry. Sexual conflict over female remating rate appears to be present in this species, with males using their apyrene sperm to exploit a female system designed to monitor sperm in storage. Ejaculates with a high proportion of nonfertile sperm may have evolved to induce females to store more of these sperm, thereby reducing remating. As a counter-adaptation, females have evolved a better detection system to regain control over their remating rate. Sexually antagonistic co-evolution of apyrene sperm number and female sperm storage may be responsible for ejaculates with predominantly nonfertile sperm in this butterfly.
Comparison of genetic differentiation at marker loci and quantitative traits
Authors: Merilä J. , Crnokrak P.
Published: March 2003

The comparison of the degree of differentiation in neutral marker loci and genes coding quantitative traits with standardized and equivalent measures of genetic differentiation (FST and QST, respectively) can provide insights into two important but seldom explored questions in evolutionary genetics: (i) what is the relative importance of random genetic drift and directional natural selection as causes of population differentiation in quantitative traits, and (ii) does the degree of divergence in neutral marker loci predict the degree of divergence in genes coding quantitative traits? Examination of data from 18 independent studies of plants and animals using both standard statistical and meta-analytical methods revealed a number of interesting points. First, the degree of differentiation in quantitative traits (QST) typically exceeds that observed in neutral marker genes (FST), suggesting a prominent role for natural selection in accounting for patterns of quantitative trait differentiation among contemporary populations. Second, the FST – QST difference is more pronounced for allozyme markers and morphological traits, than for other kinds of molecular markers and life-history traits. Third, very few studies reveal situations were QST < FST, suggesting that selection pressures, and hence optimal phenotypes, in different populations of the same species are unlikely to be often similar. Fourth, there is a strong correlation between QST and FST indices across the different studies for allozyme (r=0.81), microsatellite (r=0.87) and combined (r=0.75) marker data, suggesting that the degree of genetic differentiation in neutral marker loci is closely predictive of the degree of differentiation in loci coding quantitative traits. However, these interpretations are subject to a number of assumptions about the data and methods used to derive the estimates of population differentiation in the two sets of traits.
The use of marker-based relationship information to estimate the heritability of body weight in a natural population: a cautionary tale
Authors: Thomas S. C. , Coltman D. W. , Pemberton J. M.
Published: March 2003

A number of procedures have been developed that allow the genetic parameters of natural populations to be estimated using relationship information inferred from marker data rather than known pedigrees. Three published approaches are available; the regression, pair-wise likelihood and Markov Chain Monte Carlo (MCMC) sib-ship reconstruction methods. These were applied to body weight and molecular data collected from the Soay sheep population of St. Kilda, which has a previously determined pedigree. The regression and pair-wise likelihood approaches do not specify an exact pedigree and yielded unreliable heritability estimates, that were sensitive to alteration of the fixed effects. The MCMC method, which specifies a pedigree prior to heritability estimation, yielded results closer to those determined using the known pedigree. In populations of low average relationship, such as the Soay sheep population, determination of a reliable pedigree is more useful than indirect approaches that do not specify a pedigree.
Sexually antagonistic selection on primate size
Authors: Lindenfors P.
Published: March 2003

Male intrasexual selection in haplorhine primates has previously been shown to increase male size and to a lesser degree also female size. I address the following questions: (1) why does female size increase when the selection is on males, and (2) why does female size not increase to the same extent as that of males. The potential for correlational selection on females through increased resource competition was analysed with independent contrasts analyses. No such effect was found, nor did matched pairs comparisons reveal females to increase in size because of selection to bear larger male offspring. Instead further matched pairs analyses revealed higher female postpartum investment, as indicated by a longer lactation period, in more sexually selected species, also after correcting for body weight. Concerning the second question, independent contrast analyses showed that large size has had negative effects on female reproductive rate across the primate order. Matched-pairs analyses on haplorhines revealed that females of species in more polygynous clades have lower reproductive rates than females of species in less polygynous clades. This is also true after the effects of body weight are removed. These results, both when correcting for body weight and when not, suggest that sexual selection has shifted female size from one favouring female lifetime fecundity to one favouring male success in competition. This depicts antagonistic selection pressures on female size and a trade-off for females between the ecologically optimal size of their foremothers and the larger size that made their forefathers successful.
Female choice of sexually antagonistic male adaptations: a critical review of some current research
Authors: Cordero C. , Eberhard W. G.
Published: March 2003

We contrast some recent uses of the concept of male-female conflict, with the type of conflict that is inherent in traditional Darwinian female choice. Females in apparent conflict situations with males may suffer reduced lifetime reproduction, but nevertheless benefit because they obtain sons with superior manipulative abilities. Female defences against male manipulations may not be ‘imperfect’ because of inability to keep pace with male evolution, but in order to screen males and favour those that are especially good manipulators. We examine the consequences of these ideas, and of the difficulties of obtaining biologically realistic measures of female costs, for some recent theoretical and empirical presentations of male–female conflict ideas, and find that male–female conflict in the new sense is less certain than has been commonly supposed. Disentangling previous sexual selection ideas and the new conflict of interest models will probably often be difficult, because the two types of payoffs are not mutually exclusive.
Inbreeding depression and genetic load of sexually selected traits: how the guppy lost its spots
Authors: Van Oosterhout C. , Trigg R. E. , Carvalho G. R. , Magurran A. E. , Hauser L. , Shaw P. W.
Published: March 2003

To date, few studies have investigated the effects of inbreeding on sexually selected traits, although inbreeding depression on such traits can play an important role in the evolution and ecology of wild populations. Sexually selected traits such as ornamentation and courtship behaviour may not be primary fitness characters, but selection and dominance coefficients of their mutations will resemble those of traits under natural selection. Strong directional selection, for instance, through female mate-choice, purges all but the most recessive deleterious mutations, and the remaining dominance variation will result in inbreeding depression once populations undergo bottlenecks. We analysed the effects of inbreeding on sexually selected traits (colour pattern and courtship behaviour) in the male guppy, Poecilia reticulata, from Trinidad, and found a significant decline in the frequency of mating behaviour and colour spots. Such effects occurred although the genetic basis of these traits, many of which are Y-linked and hemizygous, would be expected to leave relatively little scope for inbreeding depression. Findings suggest that these sexually selected traits could reflect the genetic condition or health of males, and thus may be informative mate-cue characters for female choice as suggested by the ‘good genes’ model.
An international collaborative study to establish a World Health Organization international standard for hepatitis B virus DNA nucleic acid amplification techniques
Authors: Saldanha J. , Gerlich W. , Lelie N. , Dawson P. , Heermann K. , Heath A. ,   The WHO Collaborative Study Group
Published: March 2003

Background and objectives

Twenty‐two laboratories from nine countries participated in an international collaborative study to establish a World Health Organization (WHO) international standard for hepatitis B virus (HBV) DNA nucleic acid amplification techniques (NAT).

Materials and methods

Three samples, AA, BB (both of which were lyophilized) and CC (which was a liquid preparation), were analysed using several different NAT assays. The mean HBV DNA content of each sample was determined from the study.

Results

Despite the range of assays (commercial and in‐house) used by participants, there was good agreement among the overall mean ‘equivalents’/ml obtained by the different assays, except for one laboratory (laboratory 4). The variation in estimates of log10‘equivalents’/ml was 1·75–1·25 for the three samples if results from laboratory 4 were excluded. The mean log10‘equivalents’/ml for all laboratories were 6·42 for sample AA, 6·30 for sample BB and 5·03 for sample CC (exclusion of results from laboratory 4 made little difference). The difference in titres between the two lyophilized samples (AA and BB) was not statistically significant but the titre of the frozen sample (CC) was significantly lower. Material AA (code 97/746) was accepted as the first WHO international standard for HBV DNA NAT assays and assigned a potency of 106international units (IU)/ml.

Conclusions

The titres (genome equivalents/ml) of three HBV preparations were determined by several laboratories using different NAT assays. This study enabled the establishment of an international standard, 97/746, for HBV DNA NAT assays.
An international survey of unrelated umbilical cord blood banking
Authors: Stanworth S. , Warwick R. , Fehily D. , Persaud C. , Armitage S. , Navarrete C. , Contreras M.
Published: March 2003

Objectives

To investigate operational and technical practices within the field of cord blood banking.

Materials and Methods

Cord blood banks world‐wide were invited to participate in a survey of collection, processing and testing. The survey covered a 12‐month period up to August 1998.

Results

Replies were received from 18 cord blood banks. Analysis of the survey responses demonstrated wide variations in many aspects of cord blood banking.

Conclusion

There is a need for standardization to ensure adoption of best practice.
Granulocyte transfusion: a review
Authors: Yeghen T. , Devereux S.
Published: March 2003

Neutrophils are the body’s main defence against invasion by bacteria and fungi and, below a level of 1 × 109/l, there is a direct relationship between their circulating number and the risk of systemic infection. Despite advances in supportive care, such as improved broad‐spectrum antibiotics and the haemopoietic growth factors, neutropenia following myelosuppressive chemotherapy for malignant disease remains the most important cause of treatment‐related morbidity and mortality and its most important dose‐limiting toxicity. Although there is clear theoretical, experimental and anecdotal clinical evidence supporting the use of transfused granulocytes to prevent and treat infection in neutropenia, early attempts at exploiting this clinically were unsuccessful, mainly because of difficulties in collecting a sufficient number of cells. Improvements in the technology of collection, including the use of red cell sedimenting agents, glucocorticoids and, more recently, granulocyte–colony‐stimulating factor, now allow granulocyte doses within the therapeutic range to be routinely collected. Preliminary evidence suggests clinical efficacy. However, well‐designed trials with clinically relevant end‐points will be required before granulocyte transfusion can become part of routine clinical practice.
Parvovirus B19 DNA in plasma pools and plasma derivatives
Authors: Schmidt I. , Blümel J. , Seitz H. , Willkommen H. , Löwer J.
Published: March 2003

Background and Objectives

Human parvovirus B19 (B19) has been transmitted by various plasma‐derived medicinal products. The aim of this study was to determine the frequency and the level of B19 DNA contamination in plasma pools destined for fractionation and in a broad range of plasma derivatives. In addition, removal of B19 DNA by the manufacturing process was investigated in cases where corresponding samples from plasma pool and product were available.

Materials and Methods

Plasma pool samples and blood products were tested for B19 DNA by nested polymerase chain reaction (PCR), and the viral DNA content was determined by TaqMan™ quantitative PCR.

Results

Two‐hundred and twenty two of 372 plasma pools for fractionation contained B19 DNA at concentrations of 102–108 genome equivalents/ml (geq/ml). While ≈ 65% of the DNA‐positive plasma pools were only moderately contaminated (< 105 geq/ml), 35% contained > 106 geq/ml. High frequencies of contamination were detected in Factor VIII (79 of 91), prothrombin complex concentrates (38 of 43) and Factor IX (41 of 62), where the concentration of B19 DNA ranged between 102 and 107 geq/ml. A lower level of B19 DNA contamination was found in antithrombin III (five of 26 samples), in anti‐D immunoglobulins (three of 37 samples) and in albumin (four of 51 samples), with levels ranging between 102 and 103 geq/ml. Furthermore, investigation of plasma pools for solvent/detergent plasma (S/D plasma), from two manufacturers, revealed B19 DNA in 15 of 66 batches at concentrations of 102–108 geq/ml. Similar concentrations were detected in the corresponding final S/D plasma products. Anti‐B19 immunoglobulin G (IgG) was found in plasma pools and S/D plasma at concentrations of ≈ 40 IU/ml.

Conclusion

Although positive PCR results do not necessarily reflect infectivity, these data show that B19 is a common contaminant in plasma pools and in plasma‐derived medicinal products. Considering the resistance of animal parvoviruses to inactivation by heat and chemical agents, and the absence of specific information for B19, the risk of B19 transmission by plasma products should be considered. Physicians should be aware of this problem when treating patients of B19‐related risk groups. The plasma fractionation industry should continue their efforts to avoid B19 contamination of plasma derivatives and develop methods which are effective in removing/inactivating parvovirus B19.
Immunological characterization of anti‐Mia, a red blood cell alloantibody, in Taiwan
Authors: Lo S.‐C. , Chang J.‐S. , Lin S. W.‐S. , Lin D.‐T.
Published: March 2003

Background and Objectives The red blood cell Mi III phenotype is prevalent in Asia, and its corresponding alloantibody, anti‐Mia, has been reported to cause haemolytic transfusion reactions and haemolytic disease of the newborn. However, a complete picture of the immunological characteristics of anti‐Mia is still lacking. We therefore conducted a systematic study to evaluate the potential clinical significance of this antibody.

Materials and Methods From April 1999 to March 2000, we identified 60 sera containing anti‐Mia among pretransfusion samples at a teaching hospital in Taiwan. These antibodies were tested for immunoglobulin class, thermal range and activity in a monocyte monolayer assay.

Results Thirty‐four (57%) of the antibodies were immunoglobulin M (IgM), and 15 retained their activity at 37 °C. Of those that were immunoglobulin G (IgG), 96% were of subclasses IgG1 and/or IgG3. Monocyte monolayer assay studies showed that 69% (18/26) of the IgG anti‐Mia sera were reactive.

Conclusions Our study justifies the implementation of anti‐Mia screening in Taiwan.
The recognition and treatment of the intermediate syndrome of organophosphate poisoning in a dog
Authors: Hopper Kate , Aldrich Janet , Haskins Steve C.
Published: March 2003

Objective:To discuss a new clinical presentation of organophosphate toxicity called the intermediate syndrome in a dog.

Case summary:A mixed breed dog presented with generalized weakness, hypoventilation and hypoxemia. The weakness was most marked in the thoracic limbs, cervical and respiratory muscles. The history revealed a likely exposure to an organophosphate compound. The other dog in the household demonstrated mild clinical signs of organophosphate toxicity. A blood cholinesterase level was markedly reduced. Therapy included placement of a tracheostomy tube and mechanical ventilation. The dog gradually improved over the following 8 days but had persistent cervical ventroflexion for a total of 4 weeks.

New or unique information provided:Organophosphate toxicity can present as a paralysis following the acute cholinergic crisis. The muscular weakness predominantly affects the thoracic limb and neck muscles but cranial nerve deficits can also occur. Dogs can die from the associated respiratory depression. Oxime therapy is indicated in the treatment of this syndrome.
Nutrient–drug interactions in nutritional support
Authors: Michel Kathryn E. , Higgins Charlotte
Published: March 2003

Abstract Objective: To review the types and potential consequences of diet/nutrient–drug interactions that can occur in patients receiving nutritional support.

Data sources: A literature review was performed using Ovid multi‐database searching including Medline, Agricola and Biosis.

Summary: Although very little information is currently available that pertains specifically to veterinary patients, we know from the human experience that food intake and diet composition can affect the absorption, distribution, metabolism, efficacy and toxicity of a drug. Conversely, certain drugs can alter the absorption of nutrients when administered in conjunction with food or act to antagonize nutrient metabolism or function. The different ways that incompatibility can arise between food or nutrients and drugs in patients receiving nutritional support and strategies for avoiding these problems are discussed.

Conclusions: The consequences of diet/nutrient–drug interactions include decreased tolerance of nutritional support, loss of feeding access, decreased drug efficacy, nutrient malabsorption or malassimilation, and risk of drug overdosage. Therefore, when patients receiving nutritional support experience these types of complications, a review of the diet, route of nutritional support, drugs, and timing of feeding and medication administration are indicated.
Zur Frühtherapie der  Säuglingshämangiome*
Authors: Djawari Dj.
Published: March 2003

Zusammenfassung: Bei den Säuglingshämangiomen hat sich nun seit über 10 Jahren ein Umdenken durchgesetzt. Das abwartende, als Lehrmeinung geltende Verhalten in der Therapie dieser Hautveränderungen wurde inzwischen völlig verlassen.  Wegen der Unberechenbarkeit  des Wachstums der Hämangiome werden diese einer Frühbehandlung unterzogen.  Die Kontaktkryochirurgie und Lasertherapie werden als  effektive Maßnahmen angesehen. Da jedoch über 80 % der Säuglingshämangiome zu den oberflächlichen Typen gehören, ziehen wir die Kontaktkryochirurgie als einfach durchführbare und besser wirksame Frühtherapie dieser Hautanomalien aus eigener Erfahrung vor.
Granuloma faciale – Erfolgreiche Behandlung mit Hydroxychloroquin und topischer  Steroidanwendung okklusiv –
Authors: Jazwiec‐Kanyion B. , Gründer K. , Mayser P.
Published: March 2003

Zusammenfassung: Es wird über ein Granuloma faciale = Granuloma eosinophilicum faciei bei einem  53‐jährigen gesunden Mann  in doppelter Ausprägung berichtet: paranasal und präaurikulär. Die Hautveränderungen waren unter Behandlung mit Hydroxychloroquin 2 mal 200 mg oral1 und topischer Steroidanwendung okklusiv2 im Verlauf von 2 Monaten zufriedenstellend rückläufig.
Mykosen im Kindesalter*
Authors: Bruch‐Gerharz D. , Lang K. , Ruzicka T.
Published: March 2003

Zusammenfassung: Pilzinfektionen im Kindesalter verursachen ganz unterschiedliche Krankheitsbilder, deren Spektrum von einfachen Nagelveränderungen bis zu einer schweren generalisierten Dermatitis reicht. Obwohl Mykosen der Haut und Schleimhäute gut therapierbar sind, wird ihre Diagnose nicht selten verschleppt. Die zunehmende Häufigkeit von Mykosen im Kindesalter unterstreicht jedoch die Notwendigkeit, diese Infektionskrankheit wieder konsequenter in die differentialdiagnostischen Überlegungen einzubeziehen.
Topische Immunmodulation in der Dermatologie
Authors: Hengge Ulrich R.
Published: March 2003

Zusammenfassung: Immunmodulatoren umfassen sowohl immunstimulatorische als auch immunsuppressive Medikamente. Falls erfolgreich, stellt die topische Immuntherapie eine bedeutende Verbesserung der Therapie von entzündlichen Erkrankungen, viralen Infektionen und Krebs der Haut und Schleimhäute dar. Das Konzept der Immuntherapie ist bereits seit mehr als 100 Jahren bekannt, jedoch wurden die grundlegenden Mechanismen erst in der jüngsten Vergangenheit aufgeklärt und verstanden. Die topische Immuntherapie mit obligaten Kontaktsensibilisatoren wie z. B. Diphencypron (DCP) oder Dinitrochlorobenzol (DNCB) induziert Hapten‐mediierte Immunantworten, die sowohl bei spezifischen Antigenen als auch durch die Induktion eines inflammatorischen Infiltrats Wirkung gegen virale (z. B. Verrucae vulgares) und vermutlich auch autoimmune Erkrankungen (z. B. Alopecia areata) entfalten.  Neuere Agenzien wie die Imidazoquinoline (Imiquimod und Resiquimod) bewirken eine Zytokinsekretion (Interferon‐α, Interleukin‐12, Tumor‐Nekrose‐Faktor‐α) von Monozyten und Makrophagen. Es entsteht ein lokales Th1‐dominiertes Immunmilieu, das durch Zell‐mediierte Immunität zur Therapie viraler Infektionen wie z. B. HPV, HSV, Mollusca contagiosa und Hautkrebs (z. B. initiale Plattenepithel‐ und Basalzellkarzinome) bei immunkompetenten und immunsupprimierten Patienten eingesetzt werden kann. Neben der Wirkung in einer verbesserten Antigenpräsentation durch dendritische Zellen haben diese Substanzen einen Effekt auf B‐Zellen, der zur Synthese von Antikörpern der Klasse IgG2a führt. In dieser Hinsicht ähneln Imidazoquinoline den kürzlich entdeckten immunstimulatorischen CpG‐Sequenzen, die auf das angeborene („innate”) Immunsystem wirken. Diese CpG‐Sequenzen wirken als „Gefahrensignal” und kommen in bakterieller und viraler DNA vor, während sie in Säugerzell‐DNA methyliert und somit inaktiviert sind. Sowohl die CpG‐stimulatorischen Sequenzen als auch die Imidazoquinoline induzieren die gleichen Zytokine jedoch mit unterschiedlicher Intensität und Kinetik. Andererseits wird das topisch wirksame Immunsuppressivum Tacrolimus mit großem Erfolg bei der Behandlung chronisch‐entzündlicher Hauterkrankungen  – wie der atopischen Dermatitis – bei Kindern und Erwachsenen eingesetzt. Die topische Immuntherapie mit immunstimulatorischen und immunsuppressiven Agenzien birgt ein großes Potential für eine effektive und patientenfreundliche Behandlung verschiedener infektiöser und maligner Hauterkrankungen. Aufgrund ihrer Adjuvanseigenschaften sind Immunverstärker eventuell auch geeignet, konventionelle (Protein‐) und DNA‐Vakzinierungen gegen Krebs, Atopie und Allergie in ihrer Effizienz zu verbessern.