Pseudomonas aeruginosa bloodstream infections in children and adolescents: risk factors associated with carbapenem resistance and mortality.

BACKGROUND: Pseudomonas aeruginosa bloodstream infections (PA-BSIs) are a serious disease and a therapeutic challenge due to increasing resistance to carbapenems. Our objectives were to describe the prevalence and risk factors associated with carbapenem resistance (CR) and mortality in children with PA-BSI. METHODS: A retrospective, multi-centre study was carried out, including patients aged <20 years with PA-BSI in four tertiary hospitals in Madrid (Spain) during 2010-2020. Risk factors for CR PA-BSIs and 30-day mortality were evaluated in a multi-variable logistic regression model. RESULTS: In total, 151 patients with PA-BSI were included, with a median age of 29 months (interquartile range: 3.5-87.1). Forty-five (29.8%) cases were CR, 9.9% multi-drug resistant and 6.6% extensively drug resistant. The prevalence of CR remained stable throughout the study period, with 26.7% (12/45) of CR mediated by VIM-type carbapenemase. Patients with BSIs produced by CR-PA were more likely to receive inappropriate empiric treatment (53.3% vs 5.7%, P<0.001) and to have been previously colonized by CR-PA (8.9% vs 0%, P=0.002) than BSIs caused by carbapenem-susceptible P. aeruginosa. CR was associated with carbapenem treatment in the previous month (adjusted odds ratio (aOR) 11.15) and solid organ transplantation (aOR 7.64). The 30-day mortality was 23.2%, which was associated with mechanical ventilation (aOR 4.24), sepsis (aOR 5.72), inappropriate empiric antibiotic therapy (aOR 5.86), and source control as a protective factor (aOR 0.16). CONCLUSION: This study shows a concerning prevalence of CR in children with PA-BSIs, leading to high mortality. Inappropriate empiric treatment and sepsis were associated with mortality. The high prevalence of CR with an increased risk of inappropriate empiric treatment should be closely monitored.

Differential response of Scots pine seedlings to variable intensity and ratio of red and far-red light.

We investigated the response to increasing intensity of red (R) and far-R (FR) light and to a decrease in R:FR ratio in Pinus sylvestris L. (Scots pine) seedling. The results showed that FR high-irradiance response for hypocotyl elongation may be present in Scots pine and that this response is enhanced by increasing light intensity. However, both hypocotyl inhibition and pigment accumulation were more strongly affected by the R light compared with FR light. This is in contrast to previous reports in Arabidopsis thaliana (L.) Heynh. In the angiosperm, A. thaliana R light shows an overall milder effect on inhibition of hypocotyl elongation and on pigment biosynthesis compared with FR suggesting conifers and angiosperms respond very differently to the different light regimes. Scots pine shade avoidance syndrome with longer hypocotyls, shorter cotyledons and lower chlorophyll content in response to shade conditions resembles the response observed in A. thaliana. However, anthocyanin accumulation increased with shade in Scots pine, which again differs from what is known in angiosperms. Overall, the response of seedling development and physiology to R and FR light in Scots pine indicates that the regulatory mechanism for light response may differ between gymnosperms and angiosperms.

Fungal Infection Increases the Rate of Somatic Mutation in Scots Pine (Pinus sylvestris L.).

Somatic mutations are transmitted during mitosis in developing somatic tissue. Somatic cells bearing the mutations can develop into reproductive (germ) cells and the somatic mutations are then passed on to the next generation of plants. Somatic mutations are a source of variation essential to evolve new defense strategies and adapt to the environment. Stem rust disease in Scots pine has a negative effect on wood quality, and thus adversely affects the economy. It is caused by the 2 most destructive fungal species in Scandinavia: Peridermium pini and Cronartium flaccidum. We studied nuclear genome stability in Scots pine under biotic stress (fungus-infected, 22 trees) compared to a control population (plantation, 20 trees). Stability was assessed as accumulation of new somatic mutations in 10 microsatellite loci selected for genotyping. Microsatellites are widely used as molecular markers in population genetics studies of plants, and are particularly used for detection of somatic mutations as their rate of mutation is of a much higher magnitude when compared with other DNA markers. We report double the rate of somatic mutation per locus in the fungus-infected trees (4.8×10(-3) mutations per locus), as compared to the controls (2.0×10(-3) mutations per locus) when individual samples were analyzed at 10 different microsatellite markers. Pearson's chi-squared test indicated a significant effect of the fungal infection which increased the number of mutations in the fungus-infected trees (χ(2) = 12.9883, df = 1, P = 0.0003134).

Ecotypic variation in response to light spectra in Scots pine (Pinus sylvestris L.).

We investigated Scots pine adaptive responses to the light spectra by measuring hypocotyl length in seeds sampled from three natural Scots pine ecotypes across a latitudinal cline ranging from 63° to 68° N in Sweden where the adaptive cline is known to be steeper. Seeds were germinated under dark (D) and three monochromatic continuous light wavelengths: blue (B), red (R) and far-red (FR). Analysis of variance revealed a northward decrease in the inhibitory effect of FR with respect to D, the so-called far red high irradiance response. Ecotypic variation for hypocotyl development was observed under the FR and D treatments, while the trends for the B and R treatments were not statistically significant. Under FR the ecotypic variation showed an increase in hypocotyl length northwards, in contrast to the treatment under D which showed a decrease in the hypocotyl length northwards. These results could be interpreted in view of the previously reported northward increase in FR requirement to maintain growth in Norway spruce and Scots pine. Prior to the performance of the main light experiment, the maternal effect on progeny performance was investigated, which showed the absence of maternal environment effect on the performance of the seedlings.

Maternal heterozygosity and progeny fitness association in an inbred Scots pine population.

Associations between heterozygosity and fitness traits have typically been investigated in populations characterized by low levels of inbreeding. We investigated the associations between standardized multilocus heterozygosity (stMLH) in mother trees (obtained from12 nuclear microsatellite markers) and five fitness traits measured in progenies from an inbred Scots pine population. The traits studied were proportion of sound seed, mean seed weight, germination rate, mean family height of one-year old seedlings under greenhouse conditions (GH) and mean family height of three-year old seedlings under field conditions (FH). The relatively high average inbreeding coefficient (F) in the population under study corresponds to a mixture of trees with different levels of co-ancestry, potentially resulting from a recent bottleneck. We used both frequentist and Bayesian methods of polynomial regression to investigate the presence of linear and non-linear relations between stMLH and each of the fitness traits. No significant associations were found for any of the traits except for GH, which displayed negative linear effect with stMLH. Negative HFC for GH could potentially be explained by the effect of heterosis caused by mating of two inbred mother trees (Lippman and Zamir 2006), or outbreeding depression at the most heterozygote trees and its negative impact on the fitness of the progeny, while their simultaneous action is also possible (Lynch. 1991). However,since this effect wasn't detected for FH, we cannot either rule out that the greenhouse conditions introduce artificial effects that disappear under more realistic field conditions.

Simultaneous estimation of multiple quantitative trait loci and growth curve parameters through hierarchical Bayesian modeling.

A novel hierarchical quantitative trait locus (QTL) mapping method using a polynomial growth function and a multiple-QTL model (with no dependence in time) in a multitrait framework is presented. The method considers a population-based sample where individuals have been phenotyped (over time) with respect to some dynamic trait and genotyped at a given set of loci. A specific feature of the proposed approach is that, instead of an average functional curve, each individual has its own functional curve. Moreover, each QTL can modify the dynamic characteristics of the trait value of an individual through its influence on one or more growth curve parameters. Apparent advantages of the approach include: (1) assumption of time-independent QTL and environmental effects, (2) alleviating the necessity for an autoregressive covariance structure for residuals and (3) the flexibility to use variable selection methods. As a by-product of the method, heritabilities and genetic correlations can also be estimated for individual growth curve parameters, which are considered as latent traits. For selecting trait-associated loci in the model, we use a modified version of the well-known Bayesian adaptive shrinkage technique. We illustrate our approach by analysing a sub sample of 500 individuals from the simulated QTLMAS 2009 data set, as well as simulation replicates and a real Scots pine (Pinus sylvestris) data set, using temporal measurements of height as dynamic trait of interest.

Joint analysis of spatial genetic structure and inbreeding in a managed population of Scots pine.

We have investigated the fine-scale spatial genetic structure in a managed Scots pine forest. For this purpose, we perform a Bayesian genetic-cluster analysis of 96 geographically mapped individual seed trees of Swedish Scots pine based on 14 microsatellite loci. The analysis was carried out with the recently developed program GENECLUST (François et al., 2006), which provides the facility to jointly incorporate both spatial information from a geographical neighborhood structure through a Potts-Dirichlet model and account for variable degrees of inbreeding within the clusters. To evaluate whether inbreeding and spatial interaction should be included in the best-fitting statistical model for our data, we used the deviance information criterion (DIC), a weighted measure of model fit that accounts for an effective number of free parameters in a model. Analysis shows that a model with a single estimated cluster, with high levels of inbreeding (0.25) and with a moderate amount of spatial dependency within the unique cluster (Psi=0.2-0.4), best explains the data. We also carried out Bayesian parentage analysis, which enabled us to exclude the possibility that the sample constitutes one single full-sib family.

[Strabismus and congenital cataracts]. / Estrabismo y cataratas congénitas.

PURPOSE: To study the prevalence, characteristics, indications for and results of strabismus treatment secondary to congenital cataracts. MATERIALS AND METHODS: This was a retrospective study of 21 cases from 29 with congenital cataracts with strabismus (unilateral in 11 and bilateral in 10 cases). In 20 patients surgery on the cataracts was performed, with an intraocular lens inserted in 15 patients. Botulinum toxin and/or strabismus surgery were deemed to be indicated when the deviation was stable after rehabilitation therapy. A good motor end result was considered when the final deviation was < or =5 degrees, and a good sensorial result was when there was no suppression in the Worth test even without stereopsis in the TNO test. RESULTS: The strabismus prevalence was 72.4%. Strabismus was present before cataract surgery was performed in 12 cases, 8 with esotropia (ET) and 4 with exotropia (XT). Strabismus which appeared after cataract surgery was classified as 13 ET, 5 XT, 1 ET with vertical anisotropia in <>, and 2 XT with dissociated vertical deviation (DVD). The strabismus angle was variable in 6 patients and was not treated. The other 6 cases required strabismus treatment. Botulinum toxin was injected as the only treatment in 1 patient, strabismus surgery was performed in 4, and strabismus surgery and botulinum toxin were used in another case. The average age at the time of treatment was 5.2 years. The motor result was good in 5 cases (83.3%) and the sensorial result good in two (33.3%). CONCLUSIONS: Strabismus secondary to congenital cataracts occurred in a significant number of patients and increased after cataract extraction. Esotropia occurred twice as often as exotropia. Strabismus surgery was not required in most of the cases. The motor results were better than sensorial results.

Comparing Bayesian estimates of genetic differentiation of molecular markers and quantitative traits: an application to Pinus sylvestris.

Comparison of the level of differentiation at neutral molecular markers (estimated as F(ST) or G(ST)) with the level of differentiation at quantitative traits (estimated as Q(ST)) has become a standard tool for inferring that there is differential selection between populations. We estimated Q(ST) of timing of bud set from a latitudinal cline of Pinus sylvestris with a Bayesian hierarchical variance component method utilizing the information on the pre-estimated population structure from neutral molecular markers. Unfortunately, the between-family variances differed substantially between populations that resulted in a bimodal posterior of Q(ST) that could not be compared in any sensible way with the unimodal posterior of the microsatellite F(ST). In order to avoid publishing studies with flawed Q(ST) estimates, we recommend that future studies should present heritability estimates for each trait and population. Moreover, to detect variance heterogeneity in frequentist methods (ANOVA and REML), it is of essential importance to check also that the residuals are normally distributed and do not follow any systematically deviating trends.

Comparing EST-based genetic maps between Pinus sylvestris and Pinus taeda.

A genetic map of Pinus sylvestris was constructed using ESTP (expressed sequence tag polymorphism) markers and other gene-based markers, AFLP markers and microsatellites. Part of the ESTP markers (40) were developed and mapped earlier in Pinus taeda, and additional markers were generated based on P. sylvestris sequences or sequences from other pine species. The mapping in P. sylvestris was based on 94 F(1) progeny from a cross between plus-tree parents E635C and E1101. AFLP framework maps for the parent trees were first constructed. The ESTP and other gene sequence-based markers were added to the framework maps, as well as five published microsatellite loci. The separate maps were then integrated with the aid of AFLPs segregating in both trees (dominant segregation ratios 3:1) as well as gene markers and microsatellites segregating in both parent trees (segregation ratios 1:1:1:1 or 1:2:1). The integrated map consisted of 12 groups corresponding to the P. taeda linkage groups, and additionally three and six smaller groups for E1101 and E635C, respectively. The number of framework AFLP markers in the integrated map is altogether 194 and the number of gene markers 61. The total length of the integrated map was 1,314 cM. The set of markers developed for P. sylvestris was also added to existing maps of two P. taeda pedigrees. Starting with a mapped marker from one pedigree in the source species resulted in a mapped marker in a pedigree of the other species in more than 40% of the cases, with about equal success in both directions. The maps of the two species are largely colinear, even if the species have diverged more than 70 MYA. Most cases of different locations were probably due to problems in identifying the orthologous members of gene families. These data provide a first ESTP-containing map of P. sylvestris, which can also be used for comparing this species to additional species mapped with the same markers.

Nucleotide diversity at two phytochrome loci along a latitudinal cline in Pinus sylvestris.

Forest tree species provide many examples of well-studied adaptive differentiation, where the search for the underlying genes might be possible. In earlier studies and in our common conditions in a greenhouse, northern populations set bud earlier than southern ones. A difference in latitude of origin of one degree corresponded to a change of 1.4 days in number of days to terminal bud set of seedlings. Earlier physiological and ecological genetics work in conifers and other plants have suggested that such variation could be governed by phytochromes. Nucleotide variation was examined at two phytochrome loci (PHYP and PHYO, homologues of the Arabidopsis thaliana PHYB and PHYA, respectively) in three populations: northern Finland, southern Finland and northern Spain. In our samples of 12-15 sequences (2980 and 1156 base pairs at the two loci) we found very low nonsynonymous variation; pi was 0.0003 and 0.0002 at PHYP and PHYO loci, respectively. There was no functional differentiation between populations at the photosensory domains of either locus. The overall silent variation was also low, only 0.0024 for the PHYP locus. The low estimates of silent variation are consistent with the estimated low synonymous substitution rates between Pinus sylvestris and Picea abies at the PHYO locus. Despite the low level of nucleotide variation, haplotypic diversity was relatively high (0.42 and 0.41 for fragments of 1156 nucleotides) at the two loci.

[Myocardial revascularization in patients with acute myocardial infarction complicated with shock]. / Revascularización miocárdica en pacientes con infarto agudo del miocardio complicado con choque.

In the last 20 years, the acute myocardial infarction 30 day mortality rate has been reduced significantly, following pharmacological and mechanical reperfusion therapies. Nevertheless, cardiogenic shock complicating acute myocardial infarction remains the leading cause of death because of the extensive ventricular function damage non. Randomized studies were over optimistic reporting markedly lower mortality rates among patients who had undergone revascularization for shock. Further randomised studies showed that the angiographic improvement is not always followed by a significant mortality reduction. However, angiographic study and revascularisation is the treatment of choice. In addition to an early reperfusion, new pharmacological and/or genetic ways to improve the ventricular function have to be found.

Transjugular liver biopsy in 52 patients with an automated Trucut-type needle.

A three-year prospective study was conducted to assess the efficacy and safety of transjugular liver biopsy with a Trucut-type needle employing an automated device. Fifty-two consecutive patients (39 women and 13 men), ages 46.3+/-14.6 years, in whom percutaneous liver biopsy was contraindicated were included in the study. An 18-gauge transjugular hepatic needle with a 20-mm throw length, a cutting cannula at the distal end, and an automated trigger device on the proximal end was used. All procedures were performed under fluoroscopic control, and the following variables were assessed: (1) number of passes, (2) size and average number of the obtained fragments, (3) number of portal triads, and (4) adequacy of the specimen for histologic diagnosis. The procedure was successful in 49/52 patients, and all samples obtained were satisfactory for histologic analysis even when cirrhosis or bridging fibrosis were present. Mean biopsy specimen length was 1.7+/-0.88 cm; mean number of passes was 2.42+/-1.01, the mean number of biopsy fragments and portal triads per attempt were 2.5+/-1.01 and 6.24+/-3.18, respectively. No major complications were observed. Transjugular hepatic biopsy with this new cutting system is an effective and safe procedure in patients with contraindication for percutaneous liver biopsy.