Extensive mitochondrial introgression in North American Great Black-backed Gulls (Larus marinus) from the American Herring Gull (Larus smithsonianus) with little nuclear DNA impact.

Recent genetic studies have shown that introgression rates among loci may greatly vary according to their location in the genome. In particular, several cases of mito-nuclear discordances have been reported for a wide range of organisms. In the present study, we examine the causes of discordance between mitochondrial (mtDNA) and nuclear DNA introgression detected in North American populations of the Great Black-backed Gull (Larus marinus), a Holarctic species, from the Nearctic North American Herring Gull (Larus smithsonianus). Our results show that extensive unidirectional mtDNA introgression from Larus smithsonianus into Larus marinus in North America cannot be explained by ancestral polymorphism but most likely results from ancient hybridization events occurring when Larus marinus invaded the North America. Conversely, our nuclear DNA results based on 12 microsatellites detected very little introgression from Larus smithsonianus into North American Larus marinus. We discuss these results in the framework of demographic and selective mechanisms that have been postulated to explain mito-nuclear discrepancies. We were unable to demonstrate selection as the main cause of mito-nuclear introgression discordance but cannot dismiss the possible role of selection in the observed pattern. Among demographic explanations, only drift in small populations and bias in mate choice in an invasive context may explain our results. As it is often difficult to demonstrate that selection may be the main factor driving the introgression of mitochondrial DNA in natural populations, we advocate that evaluating alternative demographic neutral hypotheses may help to indirectly support or reject hypotheses invoking selective processes.

Meta-analysis of passive immunoprophylaxis in paediatric patients at risk of severe RSV infection.

AIM: To review respiratory syncytial virus (RSV), passive immunoprophylaxis (PI) trials and meta-analysis (MA). METHODS: A literature review. RESULTS: Two MA of PI were found. Overall 3927 patients were randomized. PI reduces RSV hospitalization in patients with bronchopulmonary dysplasia (RR 0.58; 95% CI 0.41, 0.82) and with acyanotic congenital heart disease (RR 0.29; 95% CI 0.14, 0.62). In patients with cyanotic heart disease or premature infants without bronchopulmonary dysplasia, results are inconclusive. Passive immunoprophylaxis has a null effect in mechanical ventilation and death. CONCLUSION: Passive immunoprophylaxis reduces RSV hospitalization in a subset of patients. However, it has no effect in harder endpoints of RSV disease severity.

Management and outcomes in digestive cancer surgery: design and initial results of a multicenter cohort study.

BACKGROUND: most studies that analyze the influence of structure factors on clinical outcomes are retrospective, based on clinical-administrative databases, and mainly focusing on surgical volume. OBJECTIVE: to study variations in the process and outcomes of oncologic surgery for esophagus, stomach, pancreas, liver metastases and rectum cancers in Catalonia, as well as the factors associated with these variations. PATIENTS AND METHOD: a retrospective (2002) and prospective (2003-05) multicenter cohort study. Data forms were designed to collect patient, process, and care outcome characteristics before surgery, at hospital discharge, and at 3 and 6 months after discharge. Main outcome measures were hospital and follow-up mortality, complications, re-interventions, and relapse rates. RESULTS: 49 hospitals (80%) participated in the retrospective phase, 44 of which (90%) also participated in the prospective phase: 3,038 patients (98%) were included. No differences were observed in the profile of operated patients according to hospital level of complexity, but clinical-pathological staging and other functional status variables could not be assessed because of over 20% of missing values. There was significant variability in the volume of interventions as well as in certain aspects of the healthcare process depending on type of cancer and center complexity. High rates of esophageal cancer mortality (18.2% at discharge, 27.3% at 6 months) and of complications and re-interventions for all cancers assessed, especially rectal cancer (18.4% re-interventions at 6 months), were identified. CONCLUSIONS: the study of the variability identified will require adequate risk-adjustment and should take into account different structure factors. It is necessary that information included in medical records be improved.

Speciation with gene flow in the large white-headed gulls: does selection counterbalance introgression?

We investigated the role of selection in generating and maintaining species distinctness in spite of ongoing gene flow, using two zones of secondary contact between large gull species in Europe (Larus argentatus and Larus cachinnans) and North America (Larus glaucescens and Larus occidentalis). We used the pattern of neutral genetic differentiation at nine microsatellite loci (F(ST)) as an indicator of expected changes under neutral processes and compared it with phenotypic differentiation (P(ST)) for a large number of traits (size, plumage melanism and coloration of bare parts). Even assuming very low heritability, interspecific divergence between L. glaucescens and L. occidentalis in plumage melanism and orbital ring colour clearly exceeded neutral differentiation. Similarly, melanism of the central primaries was highly divergent between L. argentatus and L. cachinnans. Such divergence is unlikely to have arisen randomly and is therefore attributed to spatially varying selection. Variation in plumage melanism in both transects agrees with Gloger's rule, which suggests that latitude (and associated sun and humidity gradients) could be the selective pressure shaping differentiation in plumage melanism. We suggest that strong species differentiation in orbital ring colour results from sexual selection. We conclude that these large gull species, along with other recently diverged species that hybridize after coming into secondary contact, may differ only in restricted regions of the genome that are undergoing strong disruptive selection because of their phenotypic effects.

Molecular and morphological patterns of introgression between two large white-headed gull species in a zone of recent secondary contact.

Incomplete reproductive isolation promotes gene flow between diverging taxa. However, any gene encoding for traits involved in the reproductive barriers will be less prone to introgression than neutral markers. Comparing introgression rates among loci is thus informative of the number and functions of loci involved in the reproductive barriers. This study aimed at identifying possible mechanisms of restriction to gene flow across a zone of recent secondary contact between Larus argentatus and Larus cachinnans by comparing introgression patterns for nine microsatellite loci, a fragment of mitochondrial DNA and a set of phenotypic traits. The low linkage disequilibrium between neutral nuclear markers indicated introgression without any barrier to gene flow. However, asymmetric introgression of mitochondrial DNA suggested that interspecific crosses may be more successful in one direction. The introgression rate for phenotypic traits was variable and low compared to neutral molecular markers. This was particularly evident in colouration of bare parts: individuals with intermediate colouration were scarcer in sympatry than expected if the genomes recombined freely. We hypothesized that one of these variables, the orbital ring colour, may play a role in mate choice, acting as an incomplete premating barrier through assortative mating. This study emphasizes that multilocus approaches are useful to discriminate among possible mechanisms responsible for the maintenance of hybrid zones.

Phylogenetic relationships within the Laridae (Charadriiformes: Aves) inferred from mitochondrial markers.

Gulls (Aves: Laridae) constitute a recent and cosmopolite family of well-studied seabirds for which a robust phylogeny is needed to perform comparative and biogeographical analyses. The present study, the first molecular phylogeny of all Larids species (N=53), is based on a combined segment of mtDNA (partial cytochrome b and control region). We discuss our phylogenetic tree in the light of previous suggestions based on morphological, behavioral, and plumage characters. Although the phylogeny is not fully resolved, it highlights several robust species groups and confirms or identifies for the first time some sister relationships that had never been suggested before. The Dolphin Gull (Leucophaeus scoresbii) for instance, is identified as the sister species of the Grey Gull (Larus modestus) and the Ross's Gull (Rhodostethia rosea) forms a monophyletic group with the Little Gull (Larus minutus). Our results clearly demonstrate that the genus Larus as currently defined is not monophyletic, since current taxonomy of gulls is based on the use of convergent phenotypic characters. We propose a new systematic arrangement that better reflects their evolutionary history.

[Experimental, innovative and standard procedures. Ethics and science in the introduction of medical technology]. / Procedimiento experimental, innovador y establecido. Etica y ciencia en la introducción de la tecnología médica.

The dividing lines between experimental, innovative and standard medical procedures are frequently blurred in current clinical practice. This is even more true in the fields of surgery and implantable devices. These differ substantially from pharmacological interventions, which are better regulated.However, the character of the various medical interventions applied in human subjects should be ethically and scientifically delimited as clearly as possible. This task cannot be abandoned to personal discretion and criteria, which are currently used, especially in the field of surgical innovation. External and independent review of the risk-benefit ratio of proposed innovations should enable specification of the particular features of a technique in the patient-doctor relationship, as well as the ethical and scientific requirements for more appropriate evaluation.

C-C versus C-O anionic domino cycloalkylation of stabilized carbanions: facile one-pot stereoselective preparation of functionalized bridged bicycloalkanones and cyclic enol ethers.

alpha,alpha'-Diactivated cyclic- or acyclic ketones undergo a chemoselective base promoted (K2CO3, DBU) one-pot C-C cycloalkylation, with 1,3- and 1,4-dihalides having a cis-like fixed configuration. This reaction gives highly functionalized bicyclo[3.2.1]octan-9-one and bicyclo[4.2.1]nonan-9-one derivatives, which are easily transformed to seven- and eight-membered rings through a high yield retro-Dieckmann cleavage. Starting from trans-1,4-dibromo-2-butenes, the transformation is governed by stereoelectronic factors and leads, through a chemo- and stereoselective C-O cycloalkylation, to synthetically valuable monocyclic or fused polycyclic functionalized enol ethers of high synthetic value. Semiempirical calculations showed a small difference in energy and the late character of the transition states leading to cis and trans isomers of the corresponding fused polycyclic enol ethers. These results, although minimizing the influence of a destabilizing 1,3-interaction on the outcome of the reaction, are qualitatively in agreement with the experimental results.

Técnica anestésica combinada subaracnoidea-epidural con doble catéter en cirugía de revascularización de extremidades inferiores / combined subarachnoid-epidural anesthesia with double catheter in lower limb revascularization surgery

No disponilbe (AU)

[Sciatic nerve block. Description of a new posterior approach in the gluteal area]. / Bloqueo del nervio ciático. Descripción de un nuevo trayecto de abordaje posterior en el glúteo.

OBJECTIVE: To describe and assess the clinical usefulness of a new posterior approach for sciatic nerve block to the gluteal zone. PATIENTS AND METHODS: This prospective descriptive study of 40 adults undergoing lower limb surgery measured the difficulty, efficacy and success of the described sciatic nerve block. TECHNIQUE: the patient was placed in Sim's position for a posterior approach. A line was then drawn from the upper part of the iliac spine to the sacral hiatus. From the midpoint of that line, a second line of equal length, perpendicular to the first and medial, was then drawn. The end of that line was the point of puncture. The needle was inserted perpendicular to all planes. Mepivacaine 1.5% (0.3 ml/kg) was injected. RESULTS: The sciatic nerve was located upon the first attempt in 90% of the patients within 21.86 +/- 12.62 s. The block failed in 2.5%. Time taken to establish the block was 19.17 +/- 9.62 m. One transitory, mild complication occurred. No vascular puncture occurred. CONCLUSIONS: We describe a new approach for sciatic nerve block using only two points of osseous reference identified by palpation. The level of efficacy and safety is high.

Bloqueo del nervio ciático. descripción de un nuevo trayecto de abordaje posterior en el glúteo / Sciatic nerve block. Description of a new posterior approach in the gluteal region

Objetivos. Describir y valorar clínicamente un nuevo abordaje posterior para la anestesia del nervio ciático en el glúteo.Pacienrtes y métodos. Estudio descriptivo y prospectivo, en 40 pacientes adultos sometidos a cirugía de la extremidad inferior, valorando la dificultad, eficacia y éxito del bloqueo ciático que describimos. Técnica de bloqueo: el paciente se coloca para el abordaje posterior en posición de Sim. Se traza una línea que une la espina ilíaca posterosuperior y el hiato sacro. Otra línea perpendicular a la anterior parte de su punto medio con igual longitud y con sentido medial, indicándonos su extremo el lugar de punción. La aguja de bloqueo es insertada perpendicularmente a todos los planos, y se administra mepivacaína al 1,5 por ciento (0,3 ml/kg).Resultados. Se localizó el nervio ciático al primer intento en un 90 por ciento de los casos con un tiempo de 21,86 ñ 12,62 s. En el 10 por ciento restante se consiguió en un segundo intento con un tiempo de 68,25 ñ 38,78 s. El fallo de bloqueo fue de un 2,5 por ciento. El tiempo de instauración del bloqueo fue de 19,17 ñ 9,62 minutos. Sólo hubo una complicación transitoria y considerada leve. No hubo ninguna punción vascular.Conclusiones. Describimos un nuevo abordaje para el bloqueo del nervio ciático utilizando únicamente dos puntos de referencia óseos identificados por palpación con un alto grado de eficacia y seguridad (AU)

No disponible

Scoring system has better discriminative value than Helicobacter pylori testing in patients with dyspepsia in a setting with high prevalence of infection.

OBJECTIVE: To prospectively assess the accuracy of a scoring system to predict organic diseases in dyspeptic patients in an area of South Europe, and to compare it with that of Helicobacter pylori testing in patients with dyspepsia in an environment with high prevalence of H. pylori infection. METHODS: Symptoms and demographic data were recorded in 501 consecutive dyspeptic patients referred to an outpatient gastroenterology clinic. A simple scoring system was constructed from the predictive factors obtained in a multi-variate logistic regression analysis. Overall predictive accuracy was assessed with the c statistic. The model was validated using bootstrap techniques. The accuracy of clinical judgement and H. pylori testing to predict endoscopic diagnosis was also assessed. RESULTS: Organic dyspepsia (peptic ulcer, oesophagitis or malignancies) was diagnosed in 45% of the patients. The test for H. pylori was positive in 68%, and 29% of infected patients had an ulcer. The organic dyspepsia predictive model had an accuracy of 0.79, which decreased to 0.77 after validation adjustment. The predictive accuracies for clinical judgement and H. pylori testing were 0.69 and 0.61, respectively. The addition of H. pylori testing to the scoring system resulted in a minor improvement of the predictive accuracy. CONCLUSION: In an environment with a high rate of H. pylori infection and a low prevalence of peptic ulcer among infected patients, a scoring system has higher predictive accuracy for the diagnosis of organic disease than H. pylori testing. Moreover, in this setting, H. pylori testing adds a minimum value to the predictive capability of the scoring system.

Subjective versus statistical model assessment of mortality risk in open heart surgical procedures.

BACKGROUND: The aim of this study was to compare the predictive accuracy for open heart surgical mortality between a statistical model based on collection of clinical data and surgeons' subjective risk assessment. METHODS: Predictive discrimination of both risk assessments (surgeons' and model) was compared through the area under the receiver operating characteristic curve. Logistic regression analysis was used to assess the relation between surgeons' and model predictions to actual outcomes. Calibration of the subjective estimates was evaluated with a chi2 test. RESULTS: Overall, the area under the receiver operating characteristic curve was 0.76 for the statistical model and 0.70 for the subjective assessment. Logistic regression analysis showed that the statistical model remained significant after accounting for the subjective assessment. Calibration of subjective mortality predictions was poor. CONCLUSIONS: Surgeons' risk assessment tends to cluster in the middle ranges of risk. Subjective assessment seems accurate in identifying the two extremes of risk but is inaccurate for intermediate risk levels. A multivariate statistical model improves the accuracy of subjective predictions.

[The unequal clinical profile, quality of life and hospital mortality in patients undergoing aortocoronary bypass in the public and private centers of Catalonia. The CIRCORCA Study]. / Desigual perfil clínico, calidad de vida y mortalidad hospitalaria en pacientes operados de injerto aortocoronario en centros públicos y privados de Cataluña. El estudio CIRCORCA.

INTRODUCTION AND AIMS: The influence of the type of health care funding and management of hospital centres on hospital mortality in coronary artery bypass surgery (CABG) has not been analyzed in detail. We therefore assessed clinical and quality of life preoperative profiles and in-hospital mortality in public and private patients undergoing coronary bypass surgery in Catalonia. METHODS: Clinical questionnaires, Duke Activity Status Index (DASI) and SF-36 were preoperatively administered to all patients undergoing first coronary bypass surgery without associated procedures in Catalonia between November 1996-June 1997. In-hospital morbidity and mortality were recorded. RESULTS: Predictors of in-hospital death, including DASI, SF-36 and comorbidity scores, were significantly worse in public than in private patients. In-hospital mortality rate was more than ten times greater in public than in private patients (8.2% vs 0.7%; p < 0.001). Multivariate analysis identified private funding of health care, among others, as an independent predictor of in-hospital survival. Non evidence-based indications for surgery were significantly more common in private than in public patients (6% vs 0.7%, p < 0.001). CONCLUSIONS: a) In catalonia, the risk profile of public patients undergoing coronary bypass surgery was significantly higher than that of private patients, accounting, at least in part, for a remarkable mortality difference; b) non evidence-based indications for surgery were more common in private than in public patients; c) these unequal patterns raise questions about the adequacy of care and referral patterns in both private and public sectors.

Cardiac surgical mortality: comparison among different additive risk-scoring models in a multicenter sample.

OBJECTIVE: To compare the performance of several risk-scoring models to predict surgical mortality following open heart surgery. DESIGN: A prospective observational study. SETTING: Seven tertiary cardiac centers (3 private and 4 public and teaching hospitals) in Catalonia (Spain). PATIENTS: A consecutive sample of 1287 patients submitted to open heart surgery during a 6 1/2-month period (February 14, 1994, to August 31, 1994). INTERVENTION: None. MAIN OUTCOME MEASURE: Model discrimination capability was assessed with the c-statistic. A chi(2) test to compare observed and predicted mortality rates was used as a measure of model calibration. Performance of centers was evaluated through the standardized mortality ratio and using the center as an indicator variable in a logistic regression model. The agreement among models for individual predictions was tested using weighted K statistics. RESULTS: Models developed in other health care contexts showed, as expected, lower c-statistics and an inappropriate calibration. There were no statistically significant differences among hospitals after adjusting for baseline patients' risk factors with the use of any of the different models. Models also agree in the standardized rank of centers. Weighted K statistics indicated poor agreement among models for individual patient risk prediction. CONCLUSIONS: Models can be a useful tool to compare providers' performance and to give a more in-depth look at the process of care when appropriately customized to the context. Severity-adjusted models can also play a role in supporting the informed and subjective surgeon's assessment, but it is inappropriate to use them for individual predictions.

[Activity and morbimortality of coronary surgery in Spain]. / Actividad y morbimortalidad de la cirugía coronaria en España.

The goal of the study is to describe the current knowledge about coronary artery by-pass surgery in Spain related to activity, institutions, and clinical outcomes. A search in the MEDLINE (1982-97) and IME (1976-97) databases and manual search in medical journals, official publications of scientific societies was performed. References whose authors or institutions in charge were located in Spain, and including data on activity, mortality and morbidity of coronary artery bypass surgery alone or in combination with other procedures. In 1995, 7,936 coronary procedures were carried out (alone or in combination) in 51 Spanish centres, representing an increase of 123% in those procedures registered and published in 1988. Hospital mortality, according to the Registry of the Spanish Society of Cardiovascular Surgery (1995), was 7.2%. Data from multicenter studies showed, allowing for variations among centres, 8.8% (1975-82) and 8.1% (1994) mortality in isolated coronary revascularization. Other studies refer to the particular experience in a centre, examining either predictive mortality factors or outcomes in specific clinical conditions. Surgical mortality has been only partially analysed in multicentre studies, although several groups refer to the incidence of their own specific complications. There are few multicentre studies assessing morbidity and mortality in coronary artery surgery and some results (quality of life, economical) have been poorly evaluated. An alternative to be considered is the creation of an advisory commission aimed at establishing health care standards and at supporting an information system on the patients characteristics, techniques applied, and results obtained in the provision of cardiological procedures that, due to their invasiveness, complexity and cost, can be considered as tertiary cardiological care.

Assessing open heart surgery mortality in Catalonia (Spain) through a predictive risk model.

OBJECTIVE: To develop a risk stratification model to assess open heart surgery mortality in Catalonia (Spain) in order to use risk-adjusted hospital mortality rates as an approach to analyze quality of care. METHODS: Data were prospectively collected through a specific data-sheet during 6 1/2 months in consecutive adult patients subjected to open heart surgery. The dependent variable was surgical mortality, and independent variables included were presurgical (sociodemographic data, clinical antecedents, morphological and functional studies) and surgical. The model was built on a subsample (70% of study population) through univariate and logistic regression analysis and validated in the rest of the sample. RESULTS: The total sample was of 1309 procedures in seven hospitals; 47% of them were valve procedures. The overall crude mortality rate was 10.9% and varied among centers (range, 2.8-14.8%). Risk factors included in the model received a weight based on the logistic regression coefficient and a score was generated for each patient. The factors with the highest weight were patient older than 80 and second reoperation. Score was stratified in five categories of increasing risk. There was a good agreement between observed and predicted mortality rates in the validation group. Overall patient distribution was as follows: 52% low risk level, 16% fair, 13% high, 12% very high, and 6% extremely high risk level. Mortality rate increased from 4.2% in the low risk to 54.4% in the highest risk group. Case mix adjustment was performed through the risk score level. There were statistically significant differences in the risk profiles of patients admitted among centers. After adjustment by risk profiles, there were no differences in mortality by hospital. CONCLUSION: A risk stratification model through a multicentric, prospective and exhaustive collection of data in all types of open heart procedures was developed. In spite of wide differences on crude rates and in the risk profiles of patients admitted, we did not find statistically significant differences in adjusted mortality rates among centers. Timely and accurate information about surgical outcomes can lead to improvements in clinical practice and quality of care.