Characterization and application of nonlinear plastic materials for post-CPA pulse compression

We demonstrate the three-fold post-chirped-pulse-amplification (post-CPA) pulse compression of a high peak power laser pulse using allyl diglycol carbonate (CR39), which was selected as the optimal material for near-field self-phase modulation out of a set of various nonlinear plastic materials, each characterized with respect to its nonlinear refractive index and optical transmission. The investigated materials could be applied for further pulse compression at high peak powers, as well as for gain narrowing compensation within millijoule-class amplifiers. The post-CPA pulse compression technique was tested directly after the first CPA stage within the POLARIS laser system, with the compact setup containing a single 1 mm thick plastic sample and a chirped mirror pair, which enabled a substantial shortening of the compressed pulse duration and, hence, a significant increase in the laser peak power without any additional modifications to the existing CPA chain.

Full characterization of the amplified spontaneous emission from a diode-pumped high-power laser system

We present the first complete temporal and spatial characterization of the amplified spontaneous emission (ASE) of laser radiation generated by a diode-pumped high-power laser system. The ASE of the different amplifiers was measured independently from the main pulse and was characterized within a time window of -10ms ≤ t ≤ 10ms and an accuracy of up to 15fs around the main pulse. Furthermore, the focusability and the energy of the ASE from each amplifier was measured after recompression. Using our analysis method, the laser components, which need to be optimized for a further improvement of the laser contrast, can be identified. This will be essential for laser-matter interaction experiments requiring a minimized ASE intensity or fluence.

All-reflective, highly accurate polarization rotator for high-power short-pulse laser systems

We present the setup of a polarization rotating device and its adaption for high-power short-pulse laser systems. Compared to conventional halfwave plates, the all-reflective principle using three zero-phase shift mirrors provides a higher accuracy and a higher damage threshold. Since plan-parallel plates, e.g. these halfwave plates, generate postpulses, which could lead to the generation of prepulses during the subsequent laser chain, the presented device avoids parasitic pulses and is therefore the preferable alternative for high-contrast applications. Moreover the device is easily scalable for large beam diameters and its spectral reflectivity can be adjusted by an appropriate mirror coating to be well suited for ultra-short laser pulses.

Clinical signs, therapy and zoonotic risk of pet guinea pigs with dermatophytosis

Systematic studies about pet guinea pigs with dermatophytosis are rare. The aim of this study was to evaluate clinical signs, therapy and zoonotic risk of pet guinea pigs with dermatophytosis. Questionnaires from both owners (n = 74) of pet guinea pigs with dermatophytosis and their veterinarians (n = 101) were analysed regarding clinical signs, therapy and data pertinent to zoonotic potential. Trichophyton (T.) mentagrophytes was found in 97% of cases. In the weeks preceding the onset of the clinical signs, a new guinea pig joined the household in 43% of cases. One third of the affected guinea pigs had lived in the household for less than 3 months. Predominant clinical signs were alopecia (83%), scaling (73%) and crusting (70%). The most commonly affected body site was the head (75%). In approximately one quarter of the cases humans showed clinical signs of dermatophytosis, in half the households, only children were affected. Skin lesions were seen most often on the face, the neck and the arms. Pet guinea pigs carrying dermatophytes must be considered a serious zoonotic risk for their owners, especially for children. A major risk factor for dermatophytosis seems to be a recent acquisition of a new guinea pig.

[Environmental factors, clinical signs, therapy and zoonotic risk of rabbits with dermatophytosis]

OBJECTIVE

The aim of this study was to evaluate the environmental factors, clinical signs, therapy and zoonotic risk of pet rabbits with dermatophytosis.

MATERIAL AND METHODS

In the present study, questionnaires with separate questions for the veterinarian and the owners were sent to veterinarians who treated rabbits with positive fungal cultures. Eleven of the questionnaires were completed by veterinarians and owners, while eight questionnaires were exclusively answered by the veterinarians. The questionnaires included questions on the environment of the animals (origin, maintenance, feeding, group size, new arrivals, changes), clinical signs, diagnosis, therapy and zoonosis.

RESULTS

Trichophyton (T.) mentagrophytes (m.) was the most frequently isolated dermatophyte species (15/19). Half of the animals were younger than five months and female rabbits were affected twice as frequently. In four of 11 cases new rabbits arrived in the household in the weeks prior to the onset of the dermatophytosis and in seven cases the affected animals lived in the household for less than three months. The typical group size was two animals and in half of the cases the companion rabbit was also affected. The rabbits most often showed alopecia with scaling and/or crusts, especially on the head, the ears being affected in half these animals. In three of 11 cases (27.3%) children in the family showed clinical signs of dermatophytosis, with lesions located on the hands, face and shoulder.

CONCLUSION

Pet rabbits with dermatophytosis must be considered a serious zoonotic risk for their owners, especially children. In this study, risk factors for dermatophytosis appear to be the recent acquisition of a new rabbit and the age of the animals.

CLINICAL RELEVANCE

In rabbits with alopecia with scaling and/or crusts on the head, a dermatophyte infection should be ruled out. The owner should be adequately informed about the zoonotic risk of dermatophytosis, especially if children live in the household.

Dermatophytes in pet Guinea pigs and rabbits

PROBLEM ADDRESSED

The frequency of dermatophytes in pet Guinea pigs and rabbits.

OBJECTIVES

To determine the frequency and types of dermatophytes in pet Guinea pigs and rabbits.

METHODS AND APPROACH

First, 2153 samples collected from pet Guinea pigs (n=1132) and rabbits (n=1021) with suspected dermatophytosis and submitted to three different laboratories for fungal culture were analysed. Subsequently, healthy Guinea pigs and rabbits, animals with skin lesions and with noncutaneous diseases were examined prospectively for dermatophytes.

RESULTS

Trichophyton (T.) mentagrophytes was the most common fungal species isolated (91.6% and 72.3% of positive cultures from Guinea pigs (n=431) and rabbits (n=83), respectively). Animals with positive fungal culture did not show any gender predisposition, but affected animals were younger than those with negative fungal culture (P<0.0001) or than healthy animals of the prospective part of the study. Dermatophytes were isolated from 14/164 healthy Guinea pigs and 0/140 healthy rabbits. In addition, fungal cultures of Guinea pigs with skin lesions (n=26) and other diseases (n=25) were positive in 7.7% and 8.0% respectively. Samples collected from 17 rabbits with skin lesions and 32 rabbits with noncutaneous disease were all negative in culture.

CONCLUSIONS

T. mentagrophytes is the most common dermatophyte in pet Guinea pigs and rabbits, asymptomatic carriers are regularly seen in Guinea pigs, but not in rabbits.

Comparison of the efficacy and safety of pantoprazole magnesium and pantoprazole sodium in the treatment of gastro-oesophageal reflux disease: a randomized, double-blind, controlled, multicentre trial

BACKGROUND

Proton pump inhibitors (PPIs) are well established as first-line agents for the treatment of moderate-to-severe gastro-oesophageal reflux disease (GORD). Although all PPIs heal oesophageal lesions and provide symptomatic relief, breakthrough symptoms may occur as acidity levels rebound. Pantoprazole magnesium (pantoprazole-Mg) has a longer elimination half-life than pantoprazole sodium (pantoprazole-Na), resulting in prolonged drug exposure.

OBJECTIVE

This study compares the clinical efficacy and safety of once-daily pantoprazole-Mg 40 mg with that of once-daily pantoprazole-Na 40 mg in the management of GORD.

METHODS

This was a randomized, double-blind, controlled, multicentre study of non-inferiority design in outpatients with GORD. The study was conducted in 53 centres in Germany from 12 May 2003 to 18 September 2003. Male or female outpatients (aged ≥18 years) with endoscopically confirmed GORD stage I-III (according to the Savary-Miller classification modified by Siewert) were enrolled. Using a computer-generated randomization list, patients were randomized to treatment with pantoprazole-Mg 40 mg plus placebo or pantoprazole-Na 40 mg plus placebo, both given once daily for 4 or 8 weeks depending on healing of oesophagitis. The primary objective was endoscopic healing at 8 weeks.

RESULTS

The intent-to-treat (ITT) group consisted of 636 patients (322 receiving pantoprazole-Mg and 314 receiving pantoprazole-Na). Endoscopically confirmed healing of reflux oesophagitis after 8 weeks occurred in 87.3% (95% CI 83.1, 90.7) of patients receiving pantoprazole-Mg and 85.0% (95% CI 80.6, 88.8) of patients receiving pantoprazole-Na (ITT population). The lower bound of the 95% CI for the between-group treatment difference was -1.3, which was within the predefined margin of non-inferiority of -10% to 0%. Healing rates after 4 weeks were superior in the pantoprazole-Mg group (72.7% [95% CI 67.5, 77.5]) compared with the pantoprazole-Na group (66.2% [95% CI 60.7, 71.5]), and the one-sided (lower bound) of the 95% CI for the difference between healing rates for the two treatments was within the predefined non-inferiority margin of -10% to 0%. Both treatments had a similar effect on GORD healing in subgroups of patients based on baseline oesophagitis grade and Helicobacter pylori status. Pantoprazole-Mg had similar efficacy to pantoprazole-Na in relieving a broad range of GORD-related symptoms across the course of the study, although symptomatic relief at 4 weeks was numerically higher in the pantoprazole-Mg group than in the pantoprazole-Na group (statistical analyses were not performed). Both treatments were well tolerated; most adverse events were of mild or moderate severity and unrelated to the study medication, and there were no unexpected safety concerns.

CONCLUSION

Pantoprazole-Mg is clinically as effective and well tolerated as pantoprazole-Na in the treatment of GORD stages I-III, demonstrating non-inferiority for oesophageal healing at 8 weeks and superior healing rates at 4 weeks associated with high levels of symptomatic relief.

Genome-wide functional element detection using pairwise statistical alignment outperforms multiple genome footprinting techniques

MOTIVATION

Comparative genomic sequence analysis is a powerful approach for identifying putative functional elements in silico. The availability of full-genome sequences from many vertebrate species has resulted in the development of popular tools, for example, the phastCons software package that search large numbers of genomes to identify conserved elements. While phastCons can analyze many genomes simultaneously, it ignores potentially informative insertion and deletion events and relies on a fixed, precomputed multiple sequence alignment.

RESULTS

We have developed a new method, GRAPeFoot, which simultaneously aligns two full genomes and annotates a set of conserved regions exhibiting reduced rates of insertion, deletion and substitution mutations. We tested GRAPeFoot using the human and mouse genomes and compared its performance to a set of phastCons predictions hosted on the UCSC genome browser. Our results demonstrate that despite the use of only two genomes, GRAPeFoot identified constrained elements at rates comparable with phastCons, which analyzed data from 28 vertebrate genomes. This study demonstrates how integrated modelling of substitutions, indels and purifying selection allows a pairwise analysis to exhibit a sensitivity similar to a heuristic analysis of many genomes.

AVAILABILITY

The GRAPeFoot software and set of genome-wide functional element predictions are freely available to download online at http://www.stats.ox.ac.uk/ approximately satija/GRAPeFoot/.

High-dose ursodeoxycholic acid therapy for nonalcoholic steatohepatitis: a double-blind, randomized, placebo-controlled trial

In uncontrolled clinical studies, ursodeoxycholic acid (UDCA) had a beneficial effect on nonalcoholic steatohepatitis (NASH). However, a large controlled trial using UDCA (13-15 mg/kg/day) was unable to confirm these results. Accordingly, a randomized, placebo-controlled study was initiated with a high dose of UDCA (23-28 mg/kg/day). The allocation of patients and the evaluation of liver histology were performed according to a modified Brunt score and the nonalcoholic fatty liver disease activity score (NAS). With the modified Brunt score, 185 patients with histologically proven NASH were randomized [intention to treat (ITT)], and 147 were treated per protocol (PP). With the NAS, 137 patients were confirmed to have NASH, 48 had borderline NASH, and 1 did not have NASH. The treatment time was 18 months. At entry, the treatment groups were comparable. A second biopsy sample was obtained from 139 of 185 patients (NAS: 107/137). The primary criterion for evaluation was a change in the liver histology; the secondary criteria were single histological variables and liver biochemistry. Significant differences in the overall histology could not be detected between the two treatment groups with the modified Brunt score (P = 0.881) or NAS (P = 0.355). Only lobular inflammation improved significantly (P for the modified Brunt score = 0.011, P for NAS = 0.005). In subgroup analyses, significant improvements in lobular inflammation were also observed in males, younger patients up to 50 years of age, slightly overweight patients, and patients with hypertension and an increased histology score. The fibrosis score did not change (P for ITT = 0.133, P for PP = 0.140). With the exception of gamma-glutamyl transferase, UDCA did not improve laboratory data.

CONCLUSION

High-dose UDCA failed to improve the overall histology in patients with NASH in comparison with placebo.

Psychopathology in underweight and weight-recovered females with anorexia nervosa

OBJECTIVE

To compare general and eating disorder-specific psychopathology in patients with acute anorexia nervosa (acAN), weight-recovered patients (recAN) and healthy control women (HCW).

METHODS

One hundred anorexia nervosa patients (66 acAN and 34 recAN) and 88 HCW were included in our study. Psychopathology was assessed by self-report questionnaires [Symptom Check List 90 Revised (SCL-90-R), Eating Disorder Inventory-2 (EDI- 2)] as well as by interview [Structured Interview of Anorexia Nervosa and Bulimic Syndromes (SIAB-EX)] and compared using multivariate analysis of variance. Plasma leptin levels were determined using enzyme linked immunosorbent assay.

RESULTS

Mean comparisons indicated highly significant differences between acAN and recAN subjects on all psychopatholgy variables, except for perfectionism. RecAN subjects did not differ from HCW. Partial weight recovery was associated with decreasing levels of psychopathology. Correlational analyses suggested strong negative associations between leptin levels and psychopathology.

CONCLUSION

Prolonged malnutrition, as indicated by suppressed plasma leptin levels, is strongly related to eating disorder-specific as well as general psychopathological symptoms. Weight recovery is associated with the absence of psychopathology. These data emphasize the interaction between somatic and psychological variables.

High-efficiency, room-temperature nanosecond Yb:YAG laser

Yb(3+)-doped gain media offer favorable properties for diode-pumped laser amplifiers for high-energy ns-pulses. To reach high optical-to-optical conversion efficiencies at room temperature however, very high and often impractical fluences are required both for pumping and extraction. Low temperature operation offers a solution, but the required cryogenic cooling systems add considerable complexity, bulkiness and cost. Multi-passing both pump and extraction beams through the gain medium is an alternative approach to overcome efficiency limitations at room temperature. In this article we present numerical and experimental results to this effect.We demonstrated ns-pulse output from a diode-pumped Yb:YAG amplifier at an energy of 566 mJ and an optical-to-optical efficiency of 20%, which is almost a doubling of the efficiency achieved with ns-lasers employing Yb(3+)-doped gain media at this energy level.

Clinical trial: the glucagon-like peptide-1 analogue ROSE-010 for management of acute pain in patients with irritable bowel syndrome: a randomized, placebo-controlled, double-blind study

BACKGROUND

There is currently no treatment available to manage acute pain attacks in IBS patients regardless of subtype.

AIMS

To evaluate efficacy and safety of the GLP-1 analogue ROSE-010 in patients with irritable bowel syndrome (IBS) through a randomized, double-blind, placebo-controlled study.

METHODS

Eligible patients (n = 166) meeting Rome II criteria were randomly assigned to receive single subcutaneous injections of ROSE-010 100 microg, 300 microg and placebo in a cross-over design. Safety was assessed from spontaneously reported adverse events and measurement of vital signs. Patient-rated pain relief and intensity were measured on a 100-mm visual analogue scale. The primary efficacy variable was proportion of patients with >50% maximum total pain relief response from 10 to 60 min after treatment. Secondary endpoints included the maximum summed pain intensity difference, time to meaningful pain relief and patient ratings of satisfaction with treatment.

RESULTS

Twice as many patients were responders in the primary efficacy endpoint after both ROSE-010 injections compared to placebo (24%P = 0.011, 23%P = 0.005, and 12% after 300 microg, 100 microg and placebo injections, respectively). Similar results were obtained for the proportion of patients with total pain intensity response. Times to meaningful and total pain relief were shorter for both doses of ROSE-010 compared with placebo. Compared with placebo, more patients (P < 0.05) were satisfied with ROSE-010 and considered ROSE-010 better than previous IBS medications used.

CONCLUSION

ROSE-010 was well tolerated and provided fast and effective relief of acute pain attacks on demand in IBS patients.

High-energy, diode-pumped, nanosecond Yb:YAG MOPA system

Diode-pumped nanosecond multi-pass laser amplification to the joule level using an Yb:YAG slab crystal has been demonstrated. A maximum output pulse energy of 2.9 J at an optical-to-optical efficiency of 10% has been achieved. The seed pulses with a pulse duration of 6.4 ns were generated in a Q-switched Yb:YAG laser and amplified up to a pulse energy of 200mJ in a multi-pass booster amplifier. A maximum average output power of 15W at a repetition rate of 10 Hz has been measured. We also present a relay imaging semi-stable cavity for multi-pass amplification and a diode-pumping scheme employing horizontally stacked high-power laser diodes.

Novel measurement of rapid treatment success with ReQuest: first and sustained symptom relief as outcome parameters in patients with endoscopy-negative GERD receiving 20 mg pantoprazole or 20 mg esomeprazole

BACKGROUND/AIMS

A prime concern for gastroesophageal reflux disease (GERD) patients is fast symptom control. Sparse valid information is available on the rapidity of the effect of proton pump inhibitors in providing symptom relief. The new reflux questionnaire ReQuest is validated for daily assessment of changes in GERD symptoms. Therefore, this study investigated the efficacy of 20 mg pantoprazole and 20 mg esomeprazole with regard to the time to symptom relief in patients with endoscopy-negative GERD (enGERD) using ReQuest.

METHODS

529 patients were treated with pantoprazole or esomeprazole over 4 weeks. ReQuest symptom scores were assessed daily. The mean and median times to first and sustained symptom relief were determined.

RESULTS

Median time to first symptom relief was 2 days for both drugs (intention-to-treat population). The median time to sustained symptom relief was 3 days shorter with pantoprazole (10.0 vs. 13.0 days). The Hodges-Lehmann estimator for the difference in time to reach first and sustained symptom relief between both groups was 0.00 days. For both variables the one-sided 95% CI (Moses) was [0.00; infinity[, documenting no significant differences between the treatment groups.

CONCLUSIONS

The rapidity of symptom control can be evaluated by clinically significant parameters using ReQuest. Pantoprazole and esomeprazole are equally effective in the time to first and sustained symptom relief.

[Alcohol-related disorders: etiopathology and therapeutic considerations]

The scientific understanding of the neurobiological priniciples of alcoholism has made significant progress in recent years. Especially the effects of ethanol on the neurotransmitter-systems are well studied. Dopaminergic and GABAergic facilitation contribute to the stimulating effects of low doses of alcohol while many of its adverse effects are mediated by glutamatergic inhibition at higher doses. A reduced serotonine-metabolism was shown to be a risk factor for the development of an alcohol dependence. The historic success of absinthe is discussed in this context. Absinthe is a mixture of ethanol and thujone, a substance that leads to a GABAergic inhibition as well as a reduced serotonergic responsiveness. Many studies substantiate the role of cannabinoid as well as striatal opiate-receptors in alcohol-related disorders. Neuroimaging studies could prove the important role of the reward system in this connection. Genetic factors were shown to be predisposing, however biological and environmental factors have a regulatory effect on the gene expression. Disturbances of the hpa-axis (hypothalamus-pituitary gland-adrenal cortex) were also shown to play a role in alcohol dependence. The understanding of these neurobiological principles of alcohol-related disorders should contribute to enhance and improve their therapeutic options.

[Aggressive and impulsive behavior: neurobiological models explain how affectregulation might work and social skills develop]

A person's impulsive actions are characterized by a lack of sufficient planning or an assessment of possibly harmful consequences. An impulse control disorder can be diagnosed if such actions occur frequently, even in low-stress situations. In psychiatry there are a number of syndromes that are associated with an impulse control disorder. Neurobiological findings point to a reduced turnover of serotonin in the brain of persons with an impulse control disorder and aggressive behaviour. However, a reduced turnover of serotonin is also found in persons who can consume immoderate amounts of alcohol but who experience no such unpleasant effects and thus have a high risk of becoming dependent. The serotonin turnover of an individual is controlled by environmental influences in interaction with genetic factors. In this article, impulse control disorders will be discussed with regard to their origin and social effects.

Novel measurement of rapid treatment success with ReQuest: first and sustained symptom relief as outcome parameters in patients with endoscopy-negative GERD receiving 20 mg pantoprazole or 20 mg esomeprazole

BACKGROUND/AIMS

A prime concern for gastroesophageal reflux disease (GERD) patients is fast symptom control. Sparse valid information is available on the rapidity of the effect of proton pump inhibitors in provid ing symptom relief. The new reflux questionnaire ReQuest is validated for daily assessment of changes in GERD symptoms. Therefore, this study investigated the efficacy of 20 mg pantoprazole and 20 mg esomeprazole with regard to the time to symptom relief in patients with endoscopy-negative GERD (enGERD) using ReQuest.

METHODS

529 patients were treated with pantoprazole or esomeprazole over 4 weeks. ReQuest symptom scores were assessed daily. The mean and median times to first and sustained symptom relief were determined.

RESULTS

Median time to first symptom relief was 2 days for both drugs (intention-to-treat population). The median time to sustained symptom relief was 3 days shorter with pantoprazole (10.0 vs. 13.0 days). The Hodges-Lehmann estimator for the difference in time to reach first and sustained symptom relief between both groups was 0.00 days. For both variables the one-sided 95% CI (Moses) was [0.00; infinity] documenting no significant differences between the treatment groups.

CONCLUSIONS

The rapidity of symptom control can be evaluated by clinically significant parameters using ReQuest. Pantoprazole and esomeprazole are equally effective in the time to first and sustained symptom relief.

ParIS Genome Rearrangement server

SUMMARY

ParIS Genome Rearrangement is a web server for a Bayesian analysis of unichromosomal genome pairs. The underlying model allows inversions, transpositions and inverted transpositions. The server generates a Markov chain using a Partial Importance Sampler technique, and samples trajectories of mutations from this chain. The user can specify several marginalizations to the posterior: the posterior distribution of number of mutations needed to transform one genome into another, length distribution of mutations, number of mutations that have occurred at a given site. Both text and graphical outputs are available. We provide a limited server, a downloadable unlimited server that can be installed locally on any linux/Unix operating system, and a database of mitochondrial gene orders.

An efficient algorithm for statistical multiple alignment on arbitrary phylogenetic trees

We present an efficient algorithm for statistical multiple alignment based on the TKF91 model of Thorne, Kishino, and Felsenstein (1991) on an arbitrary k-leaved phylogenetic tree. The existing algorithms use a hidden Markov model approach, which requires at least O( radical 5(k)) states and leads to a time complexity of O(5(k)L(k)), where L is the geometric mean sequence length. Using a combinatorial technique reminiscent of inclusion/exclusion, we are able to sum away the states, thus improving the time complexity to O(2(k)L(k)) and considerably reducing memory requirements. This makes statistical multiple alignment under the TKF91 model a definite practical possibility in the case of a phylogenetic tree with a modest number of leaves.

Recombination, balancing selection and phylogenies in MHC and self-incompatibility genes

Using a coalescent model of multiallelic balancing selection with recombination, the genealogical process as a function of recombinational distance from a site under selection is investigated. We find that the shape of the phylogenetic tree is independent of the distance to the site under selection. Only the timescale changes from the value predicted by Takahata's allelic genealogy at the site under selection, converging with increasing recombination to the timescale of the neutral coalescent. However, if nucleotide sequences are simulated over a recombining region containing a site under balancing selection, a phylogenetic tree constructed while ignoring such recombination is strongly affected. This is true even for small rates of recombination. Published studies of multiallelic balancing selection, i.e., the major histocompatibility complex (MHC) of vertebrates, gametophytic and sporophytic self-incompatibility of plants, and incompatibility of fungi, all observe allelic genealogies with unexpected shapes. We conclude that small absolute levels of recombination are compatible with these observed distortions of the shape of the allelic genealogy, suggesting a possible cause of these observations. Furthermore, we illustrate that the variance in the coalescent with recombination process makes it difficult to locate sites under selection and to estimate the selection coefficient from levels of variability.

A molecular clock dates the common ancestor of European-type porcine reproductive and respiratory syndrome virus at more than 10 years before the emergence of disease

The disease caused by porcine reproductive and respiratory syndrome virus (PRRSV) emerged independently and almost simultaneously in Europe (1990) and North America (1987). The original reservoir of the virus and the date it entered the pig populations is not known. In this study, we demonstrate an accurate molecular clock for the European PRRSV ORF 3 gene, place the root in the genealogy, estimate the rate of nucleotide substitution, and date the most recent common viral ancestor of the data set to 1979; more than 10 years before the onset of the European epidemic. Based on these findings, we conclude that PRRSV virus most likely entered the pig population some time before the epidemic emergence of the virus, and hence, that emergence of European-type PRRSV is not the result of a recent species transmission event. Together, our results show that ORF3 sequencing is a valuable epidemiologic tool for examining the emergence and spread of PRRSV in Europe. As such, the panel of well-characterized and highly divergent ORF3 sequences described in this study provides a reference point for future molecular epidemiologic studies.

A simulation study of the reliability of recombination detection methods

There exist many methods to detect recombination or mosaic structure in a sample of DNA sequences. But how reliable are they? Four methods were investigated with respect to their power to detect recombination in simulated samples with different amounts of recombination and mutation. In addition, we investigated the impact of the shape of the underlying genealogy on their performances. We found that the methods detected far fewer recombinations than were theoretically possible and that methods based on the principle of incompatibility in general had more power than methods that did not make use of this principle explicitly. This seemed, in particular, to be the case for phylogenies generated under population expansion scenarios which result in long branches at the tips and small deep branches. In addition to the results obtained through simulations, a series of new theoretical results on recombination is presented.

Interleukin-12 and interleukin-18 are indispensable for protective immunity against enteropathogenic Yersinia

Previous results have demonstrated an essential role of gamma interferon (IFN-gamma) in resistance against Yersinia enterocolitica. Hence, we investigated the course of Yersinia infection in mice deficient for the IFN-gamma-inducing cytokines interleukin-12 (IL-12 p40(-/-)) or interleukin-18 (IL-18(-/-)). The experiments described herein argue for a critical role of both cytokines in protective immune responses against this pathogen.