Does Sex Speed Up Evolutionary Rate and Increase Biodiversity?

Most empirical and theoretical studies have shown that sex increases the rate of evolution, although evidence of sex constraining genomic and epigenetic variation and slowing down evolution also exists. Faster rates with sex have been attributed to new gene combinations, removal of deleterious mutations, and adaptation to heterogeneous environments. Slower rates with sex have been attributed to removal of major genetic rearrangements, the cost of finding a mate, vulnerability to predation, and exposure to sexually transmitted diseases. Whether sex speeds or slows evolution, the connection between reproductive mode, the evolutionary rate, and species diversity remains largely unexplored. Here we present a spatially explicit model of ecological and evolutionary dynamics based on DNA sequence change to study the connection between mutation, speciation, and the resulting biodiversity in sexual and asexual populations. We show that faster speciation can decrease the abundance of newly formed species and thus decrease long-term biodiversity. In this way, sex can reduce diversity relative to asexual populations, because it leads to a higher rate of production of new species, but with lower abundances. Our results show that reproductive mode and the mechanisms underlying it can alter the link between mutation, evolutionary rate, speciation and biodiversity and we suggest that a high rate of evolution may not be required to yield high biodiversity.

Feedback von Schülerinnen und Schülern als Quelle des Lernprozesses im Praktikum von Lehramtsstudierenden

Rückmeldungen von Schülerinnen und Schülern zum Unterricht nehmen eine wichtige Rolle zur Verbesserung der Unterrichtsqualität ein. Während der Ausbildung von Lehrpersonen wird dieses Potenzial bisher aber selten genutzt. Der Beitrag stellt Ergebnisse aus dem Forschungsprojekt "Lernen im Praktikum" vor. Befragt wurden 150 Studierende des Lehramts für 7.-9. Klassen (Sekundarstufe 1) zur Bedeutung von Schülerrückmeldungen im Praktikum sowie 1331 Schülerinnen und Schüler aus Praktikumsklassen zum Praktikum und zum Lernprozess der Praktikantinnen und Praktikanten. Die Ergebnisse unterstützen einerseits die Relevanz systematischer Schülerrückmeldungen für das Lernen im Praktikum. Andererseits machen sie auf die Notwendigkeit aufmerksam, die Kriterien, die Schülerbeurteilungen zugrunde liegen, weiter zu erforschen.

Forget about theory - practice is all? - Student teachers' learning in practicum

In 1999, all student teachers at secondary I level at the University of Bern who had to undertake an internship were asked to participate in a study on learning processes during practicum: 150 students and their mentors in three types of practicum participated—introductory practicum (after the first half‐year of studies), intermediate practicum (after two years of studies) and final practicum (after three years of studies). At the end of the practicum, student teachers and mentors completed questionnaires on preparing, teaching and post‐processing lessons. All student teachers, additionally, rated their professional skills and aspects of personality (attitudes towards pupils, self‐assuredness and well‐being) before and after the practicum. Forty‐six student teachers wrote daily semi‐structured diaries about essential learning situations during their practicum. Results indicate that in each practicum students improved significantly in preparing, conducting and post‐processing lessons. The mentors rated these changes as being greater than did the student teachers. From the perspective of the student teachers their general teaching skills also improved, and their attitudes toward pupils became more open. Furthermore, during practicum their self‐esteem and subjective well‐being increased. Diary data confirmed that there are no differences between different levels of practicum in terms of learning outcomes, but give some first insight into different ways of learning during internship.

The IFNL3/4 ΔG variant increases susceptibility to cytomegalovirus retinitis among HIV-infected patients.

BACKGROUND Cytomegalovirus (CMV) retinitis is a major cause of visual impairment and blindness among patients with uncontrolled HIV infections. Whereas polymorphisms in interferon-lambda 3 (IFNL3, previously named IL28B) strongly influence the clinical course of hepatitis C, few studies examined the role of such polymorphisms in infections due to viruses other than hepatitis C virus. OBJECTIVES To analyze the association of newly identified IFNL3/4 variant rs368234815 with susceptibility to CMV-associated retinitis in a cohort of HIV-infected patients. DESIGN AND METHODS This retrospective longitudinal study included 4884 white patients from the Swiss HIV Cohort Study, among whom 1134 were at risk to develop CMV retinitis (CD4 nadir <100 /μl and positive CMV serology). The association of CMV-associated retinitis with rs368234815 was assessed by cumulative incidence curves and multivariate Cox regression models, using the estimated date of HIV infection as a starting point, with censoring at death and/or lost follow-up. RESULTS A total of 40 individuals among 1134 patients at risk developed CMV retinitis. The minor allele of rs368234815 was associated with a higher risk of CMV retinitis (log-rank test P = 0.007, recessive mode of inheritance). The association was still significant in a multivariate Cox regression model (hazard ratio 2.31, 95% confidence interval 1.09-4.92, P = 0.03), after adjustment for CD4 nadir and slope, HAART and HIV-risk groups. CONCLUSION We reported for the first time an association between an IFNL3/4 polymorphism and susceptibility to AIDS-related CMV retinitis. IFNL3/4 may influence immunity against viruses other than HCV.

S-nitroso albumin enhances bone formation in a rabbit calvaria model.

Nitric oxide (NO) is a mediator involved in bone regeneration. We therefore examined the effect of the novel NO donor, S-nitroso human serum albumin (S-NO-HSA) on bone formation in a rabbit calvaria augmentation model. Circular grooves (8 mm diameter, two per animal) were created by a trephine drill in the cortical bone of 40 rabbits and titanium caps were placed on the rabbit calvaria bone filled with a collagen sponge soaked with either 100 μL S-NO-HSA (5%, 20%) or human albumin (5%, 20%). After 4 weeks the titanium hemispheres were subjected to histological and histomorphometric analysis. Bone formation and the volume of the residual collagen sponge were evaluated. S-NO-HSA treatment groups had a significantly higher volume of newly formed bone underneath the titanium hemispheres compared to the albumin control groups (5%: 15.5 ± 4.0% versus 10.6 ± 2.9%; P < 0.05; 20%: 14.0 ± 4.6% versus 6.0 ± 3.8%; P < 0.01). The volume of residual collagen sponge was also significantly lower in the S-NO-HSA groups compared to the control groups (5%: 0.4 ± 0.5% versus 2.6 ± 2.4%; P < 0.05 and 20%: 1.5 ± 2.7% versus 13.0 ± 18.7%; P < 0.01). This study demonstrates for the first time that S-NO-HSA promotes bone formation by slow NO release. Additionally, S-NO-HSA increases collagen sponge degradation.

Comprehensive screening for mutations associated with colorectal cancer in unselected cases reveals penetrant and nonpenetrant mutations.

Germline mutation testing in patients with colorectal cancer (CRC) is offered only to a subset of patients with a clinical presentation or tumor histology suggestive of familial CRC syndromes, probably underestimating familial CRC predisposition. The aim of our study was to determine whether unbiased screening of newly diagnosed CRC cases with next generation sequencing (NGS) increases the overall detection rate of germline mutations. We analyzed 152 consecutive CRC patients for germline mutations in 18 CRC-associated genes using NGS. All patients were also evaluated for Bethesda criteria and all tumors were investigated for microsatellite instability, immunohistochemistry for mismatch repair proteins and the BRAF*V600E somatic mutation. NGS based sequencing identified 27 variants in 9 genes in 23 out of 152 patients studied (18%). Three of them were already reported as pathogenic and 12 were class 3 germline variants with an uncertain prediction of pathogenicity. Only 1 of these patients fulfilled Bethesda criteria and had a microsatellite instable tumor and an MLH1 germline mutation. The others would have been missed with current approaches: 2 with a MSH6 premature termination mutation and 12 uncertain, potentially pathogenic class 3 variants in APC, MLH1, MSH2, MSH6, MSH3 and MLH3. The higher NGS mutation detection rate compared with current testing strategies based on clinicopathological criteria is probably due to the large genetic heterogeneity and overlapping clinical presentation of the various CRC syndromes. It can also identify apparently nonpenetrant germline mutations complicating the clinical management of the patients and their families.

Is low parental education associated with congenital heart defects?

Objective. The purpose of this study was to determine if there are associations between low parental education and congenital heart defects. ^ Methods. This was a cross-sectional study of 281,262 live born singletons, 1765 of whom were identified by the Texas Birth Defects Monitoring Division (TBDMD) as having heart defects without known chromosomal anomalies. Data on the specific diagnoses of these infants were linked to their corresponding birth certificates. Only infants born between January 1, 1995 and December 31, 1997, whose mothers resided in the Texas public health regions under surveillance by the TBDMD were included in the study. The number of years of schooling of the most educated parent was used to calculate crude, stratified and adjusted odds ratios. ^ Results. An increase in the likelihood of having an infant with any type of congenital heart defect was found among parents with less than 16 years of education, compared to those with 16 or more years of schooling. The association became more marked with increasing paternal age, and was found among whites and Hispanics but not among blacks. Statistically significant associations with low parental education were found for ventricular septal defects, transposition of the great vessels and miscellaneous heart and vessel defects. Among whites, there was an inverse association between parental education and likelihood of having an infant with a severe ASD. This association was not found among non-whites. The suggestion of an association between low parental education and tetralogy of Fallot, was also found, but was not statistically significant. Parents with ≥16 years of education had a greater likelihood of having an infant with severe endocardial cushion lesions or total anomalous pulmonary return than less well educated parents. ^ Conclusion. This study suggests that parental education is associated with certain types of heart defects, especially among whites and Hispanics. ^

The Dental School Applicant Pool and the Oral Healthcare Workforce

One of the major challenges faced by the dental profession today is the recruitment of the most qualified dental school applicants who are capable of serving the nation’s future oral healthcare needs. The Association of Schools of Public Health (ASPH) also recognizes this challenge, describing one of the three core functions of public health as “assuring that all populations have access to appropriate and cost effective care, including health promotion and disease prevention services.” To achieve this core function, the ASPH cites “a competent public health and personal healthcare workforce” as one of the ten essential public health services. Unfortunately, the goals of both quality and equality in terms of the dental workforce and access to oral healthcare have yet to be realized. When considering access to oral health services on a national or state level, a thoughtful and thorough consideration of the dental school applicant pool is essential. According to a recent study published in the Journal of the American Dental Association, the annual number of retiring dentists will exceed the number of newly licensed dental practitioners in 2009, a trend which is projected to continue throughout the next decade. The approximately 4,400 dentists produced each year from the nation’s 57 accredited dental education programs are charged with the responsibility of meeting the oral healthcare needs of the population at large.

ETIOLOGIC AND CLINICAL FACTORS WHICH DIFFERENTIATE PATIENTS WITH CHROMOSOMAL ABNORMALITIES FROM DIPLOID PATIENTS IN ACUTE NONLYMPHOCYTIC LEUKEMIA

Tumor-specific chromosomal abnormalities have been demonstrated in bone marrow of approximately 50% of newly diagnosed acute nonlymphocytic (ANLL) patients. This study examined two hypotheses: (1) Aneuploid (AA) patients are diagnosed later in the course of their disease than diploid (NN) patients; and (2) AA patients are more likely to have been exposed to environmental agents. Of 324 patients eligible for study, environmental exposure data were obtained for 236 (73%) of them. No evidence was found to suggest that AA patients had more advanced disease than NN patients. Aneuploid patients were more likely than NN patients to: (a) report treatment with cytotoxic drugs for a prior medical condition (odds ratio, adjusted for age, sex and other exposures (OR) = 4.25, 95% confidence intervals, 1.38 to 13.17); (b) smoke cigarettes, OR = 1.82 (1.02, 3.26) and (c) drink alcoholic beverages, OR = 1.91 (1.05, 3.48). No statistically significant associations between aneuploidy and occupational exposures were present, OR = 3.59 (0.76, 17.13). Problems in interpreting these ORs are discussed. ^

Geographic variation in the utilization and survival associated with oxaliplatin chemotherapy in patients with stage III colon cancer

Background: Overall objectives of this dissertation are to examine the geographic variation and socio-demographic disparities (by age, race and gender) in the utilization and survival of newly FDA-approved chemotherapy agents (Oxaliplatin-containing regimens) as well as to determine the cost-effectiveness of Oxaliplatin in a large nationwide and population-based cohort of Medicare patients with resected stage-III colon cancer. Methods: A retrospective cohort of 7,654 Medicare patients was identified from the Surveillance, Epidemiology and End Results – Medicare linked database. Multiple logistic regression was performed to examine the relationship between receipt of Oxaliplatin-containing chemotherapy and geographic regions while adjusting for other patient characteristics. Cox proportional hazard model was used to estimate the effect of Oxaliplatin-containing chemotherapy on the survival variation across regions using 2004-2005 data. Propensity score adjustments were also made to control for potential bias related to non-random allocation of the treatment group. We used Kaplan-Meier sample average estimator to calculate the cost of disease after cancer-specific surgery to death, loss-to follow-up or censorship. Results: Only 51% of the stage-III patients received adjuvant chemotherapy within three to six months of colon-cancer specific surgery. Patients in the rural regions were approximately 30% less likely to receive Oxaliplatin chemotherapy than those residing in a big metro region (OR=0.69, p=0.033). The hazard ratio for patients residing in metro region was comparable to those residing in big metro region (HR: 1.05, 95% CI: 0.49-2.28). Patients who received Oxalipaltin chemotherapy were 33% less likely to die than those received 5-FU only chemotherapy (adjusted HR=0.67, 95% CI: 0.41-1.11). KMSA-adjusted mean payments were almost 2.5 times higher in the Oxaliplatin-containing group compared to 5-FU only group ($45,378 versus $17,856). When compared to no chemotherapy group, ICER of 5-FU based regimen was $12,767 per LYG, and ICER of Oxaliplatin-chemotherapy was $60,863 per LYG. Oxaliplatin was found economically dominated by 5-FU only chemotherapy in this study population. Conclusion: Chemotherapy use varies across geographic regions. We also observed considerable survival differences across geographic regions; the difference remained even after adjusting for socio-demographic characteristics. The cost-effectiveness of Oxaliplatin in Medicare patients may be over-estimated in the clinical trials. Our study found 5-FU only chemotherapy cost-effective in adjuvant settings in patients with stage-III colon cancer.^

Rosalia de Castro y la visión poética de Galicia

Este artículo estudia la visión de la poeta española Rosalía de Castro (1837-1885) de su Galicia natal a partir de algunos de sus poemas, en especial del libro En las orillas del Sar (1884), la colección lírica considerada como la más importante de la autora. Desde el análisis de algunas piezas significativas sobre el tema de Galicia, se cubre inicialmente su visión personal de contestación a favor de su tierra natal. La segunda parte del estudio se centra en la temática social en Rosalía de Castro en relación con la defensa del emigrante gallego.

La teoría de la transición demográfica en Argentina : interpretaciones y derivaciones (1930-1950)

El trabajo tiene por objetivo mostrar cómo los círculos dirigentes de Argentina interpretaron la teoría de la transición demográfica presente en el país en los años 1930-1950 y cuales fueron las derivaciones hacia el tema del capital humano. Este concepto está atravesado por análisis sociológicos, sicológicos, biológicos de una gran vaguedad y sin rigurosos análisis sobre el desarrollo económico, partiendo de analogías no demostradas. Por consiguiente, el primer tema del trabajo se refiere a las fuentes que inspiraron a la dirigencia argentina en la asimilación de la teoría. Seguidamente, se señalan las relaciones y las analogías expuestas entre la situación demográfica argentina y la de los países industrializados de Europa. El tercer aspecto se centra en las derivaciones sociológicas, psicológicas, biológicas que extraen de la relación economía-población. Con lo cual, en forma tímida y sin claridad conceptual, se introducen en el tema del capital humano en el desarrollo económico del país.

Reflexiones metodológicas sobre algunas contribuciones de la terapia familiar sistémica a un estudio antropológico de la familia

El fenómeno migratorio ha sido tratado a partir de diferentes estudios históricos, sociológicos, demográficos y antropológicos. Muchas veces estos abordajes solo ofrecen respuestas parciales a las problemáticas que conforman la migración. Nuestras investigaciones se centraron en el estudio de grupos de inmigrantes caboverdeanos en Argentina, aportando modelos sobre la organización e interacción de esos grupos, con el fin de explorar temas críticos, como inmigración y familia, identidad y etnicidad, entre otros. Luego de años de trabajo hemos ajustado metodologías, sobre todo las derivadas de la antropología tradicional, buscando alternativas, "reciclando" premisas, pautas y técnicas de otras disciplinas como la psicología (en particular la terapia familiar de orientación sistémica). En este trabajo reflexionamos sobre algunas cuestiones metodológicas, particularmente el uso de genogramas puestos en práctica en el estudio del parentesco y de la familia caboverdeana en un contexto migratorio, cuyo análisis fue uno de los objetivos planteados en el proyecto de investigación sobre el mencionado grupo en la Argentina

Un desafío pendiente para el próximo quinquenio : Los objetivos de desarrollo del milenio

En el año 2000, los gobiernos de 189 países se comprometieron a alcanzar dieciocho metas para combatir la desigualdad y mejorar el desarrollo humano en el mundo a través del cumplimiento de los denominados Objetivos de Desarrollo del Milenio (ODM) de la Organización de las Naciones Unidas (ONU), todo ello con un horizonte para el año 2015. Los ODM deben ser monitoreados por los institutos de estadística existentes en la mayoría de los países que calculan indicadores económicos. En la Argentina, el Instituto Nacional de Estadística y Censos tiene una larga experiencia en la creación y cálculo de índices, específicamente, del índice de Precios al Consumidor el cual ha sido considerado como el mejor índice de precios de toda América Latina. Sin embargo, desde el año 2007 se ha implementado una nueva metodología para su cálculo. En esta comunicación se presentan resultados de trabajos realizados desde diferentes puntos de vista que aportan los métodos exploratorios y confirmatorios tendientes a conocer la situación de pobreza e indigencia y la distribución de los ingresos de los habitantes del Aglomerado Gran Rosario. Los análisis exploratorios y confirmatorios aplicados presentan incuestionables resultados que reflejan la coherencia de las conclusiones a que se ha arribado. Los datos primarios de calidad utilizados permitieron plasmar análisis dinámicos con la información homogénea disponible. Finalmente y a la luz de estas circunstancias, ¿se podrá saber fehacientemente si se alcanzarán los Objetivos de Desarrollo del Milenio en el año 2015?

Reflexiones sobre la gestión "integrada" de cuencas hídricas en Buenos Aires : Las redes de organización social en las políticas de saneamiento ambiental

La gestión integrada de cuencas resulta ser una directriz de los organismos internacionales. Desde la gestión local se apela a la participación social, al tiempo que las redes de organizaciones socio-territoriales reclaman mayor injerencia en procesos de control para el saneamiento de las cuencas en Buenos Aires. En cualquier caso, sobrevuelan ideas tales como "integración" (de componentes) y "participación" (de grupos y sectores), que no necesariamente son concebidas unívocamente por todos los actores sociales en juego. Mientras tanto, el control de la contaminación del agua sigue siendo una zona gris en la gestión, a pesar de la creación de autoridades de cuenca. Desde un enfoque de redes, el presente trabajo rastrea en documentos de organismos internacionales, entrevistas a funcionarios locales y miembros de organizaciones territoriales, las acepciones sobre la "gestión integrada" y la "participación" en torno a cuencas metropolitanas degradadas