Brazilian Thoracic Society recommendations for the diagnosis and monitoring of asbestos-exposed individuals.

Asbestos was largely used in Brazil. It is a mineral that induces pleural and pulmonary fibrosis, and it is a potent carcinogen. Our objective was to develop recommendations for the performance of adequate imaging tests for screening asbestos-related diseases. We searched peer-reviewed publications, national and international technical documents, and specialists' opinions on the theme. Based on that, the major recommendations are: Individuals exposed to asbestos at the workplace for ≥ 1 year or those with a history of environmental exposure for at least 5 years, all of those with a latency period > 20 years from the date of initial exposure, should initially undego HRCT of the chest for investigation. Individuals with pleural disease and/or asbestosis should be considered for regular lung cancer monitoring. Risk calculators should be adopted for lung cancer screening, with a risk estimate of 1.5%.

Lung cancer screening in Brazil: recommendations from the Brazilian Society of Thoracic Surgery, Brazilian Thoracic Association, and Brazilian College of Radiology and Diagnostic Imaging.

Although lung cancer (LC) is one of the most common and lethal tumors, only 15% of patients are diagnosed at an early stage. Smoking is still responsible for more than 85% of cases. Lung cancer screening (LCS) with low-dose CT (LDCT) reduces LC-related mortality by 20%, and that reduction reaches 38% when LCS by LDCT is combined with smoking cessation. In the last decade, a number of countries have adopted population-based LCS as a public health recommendation. Albeit still incipient, discussion on this topic in Brazil is becoming increasingly broad and necessary. With the aim of increasing knowledge and stimulating debate on LCS, the Brazilian Society of Thoracic Surgery, the Brazilian Thoracic Association, and the Brazilian College of Radiology and Diagnostic Imaging convened a panel of experts to prepare recommendations for LCS in Brazil. The recommendations presented here were based on a narrative review of the literature, with an emphasis on large population-based studies, systematic reviews, and the recommendations of international guidelines, and were developed after extensive discussion by the panel of experts. The following topics were reviewed: reasons for screening; general considerations about smoking; epidemiology of LC; eligibility criteria; incidental findings; granulomatous lesions; probabilistic models; minimum requirements for LDCT; volumetric acquisition; risks of screening; minimum structure and role of the multidisciplinary team; practice according to the Lung CT Screening Reporting and Data System; costs versus benefits of screening; and future perspectives for LCS.

Lung cancer screening in Brazil: recommendations from the Brazilian Society of Thoracic Surgery, Brazilian Thoracic Association, and Brazilian College of Radiology and Diagnostic Imaging / Recomendações da Sociedade Brasileira de Cirurgia Torácica, Sociedade Brasileira de Pneumologia e Tisiologia e Colégio Brasileiro de Radiologia e Diagnóstico por Imagem para o rastreamento do câncer de pulmão no Brasil

ABSTRACT Although lung cancer (LC) is one of the most common and lethal tumors, only 15% of patients are diagnosed at an early stage. Smoking is still responsible for more than 85% of cases. Lung cancer screening (LCS) with low-dose CT (LDCT) reduces LC-related mortality by 20%, and that reduction reaches 38% when LCS by LDCT is combined with smoking cessation. In the last decade, a number of countries have adopted population-based LCS as a public health recommendation. Albeit still incipient, discussion on this topic in Brazil is becoming increasingly broad and necessary. With the aim of increasing knowledge and stimulating debate on LCS, the Brazilian Society of Thoracic Surgery, the Brazilian Thoracic Association, and the Brazilian College of Radiology and Diagnostic Imaging convened a panel of experts to prepare recommendations for LCS in Brazil. The recommendations presented here were based on a narrative review of the literature, with an emphasis on large population-based studies, systematic reviews, and the recommendations of international guidelines, and were developed after extensive discussion by the panel of experts. The following topics were reviewed: reasons for screening; general considerations about smoking; epidemiology of LC; eligibility criteria; incidental findings; granulomatous lesions; probabilistic models; minimum requirements for LDCT; volumetric acquisition; risks of screening; minimum structure and role of the multidisciplinary team; practice according to the Lung CT Screening Reporting and Data System; costs versus benefits of screening; and future perspectives for LCS.

RESUMO O câncer de pulmão (CP) é uma das neoplasias mais comuns e letais no Brasil, e apenas 15% dos pacientes são diagnosticados nos estágios iniciais. O tabagismo persiste como o responsável por mais de 85% de todos os casos. O rastreamento do CP (RCP) por meio da TC de baixa dosagem de radiação (TCBD) reduz a mortalidade do CP em 20%, e, quando combinado com a cessação do tabagismo, essa redução chega a 38%. Na última década, diversos países adotaram o RCP como recomendação de saúde populacional. No Brasil, embora ainda incipiente, a discussão sobre o tema é cada vez mais ampla e necessária. Com o intuito de aumentar o conhecimento e estimular o debate sobre o RCP, a Sociedade Brasileira de Cirurgia Torácica, a Sociedade Brasileira de Pneumologia e Tisiologia e o Colégio Brasileiro de Radiologia e Diagnóstico por Imagem constituíram um painel de especialistas para elaborar as recomendações para o RCP. As recomendações aqui apresentadas foram baseadas em revisão narrativa da literatura, com ênfase em grandes estudos populacionais, em revisões sistemáticas e em recomendações de diretrizes internacionais, sendo construídas após ampla discussão pelo grupo de especialistas. Os temas revisados foram os seguintes: porque rastrear, considerações gerais sobre tabagismo, epidemiologia do CP, critérios de elegibilidade, achados incidentais, lesões granulomatosas, modelos probabilísticos, requisitos mínimos da TCBD, aquisições volumétricas, riscos do rastreamento, estrutura mínima e papel da equipe multidisciplinar, conduta segundo o Lung CT Screening Reporting and Data System (Lung-RADS), custos vs. benefícios e perspectivas do rastreamento.

Brazilian Thoracic Society recommendations for the diagnosis and monitoring of asbestos-exposed individuals

ABSTRACT Asbestos was largely used in Brazil. It is a mineral that induces pleural and pulmonary fibrosis, and it is a potent carcinogen. Our objective was to develop recommendations for the performance of adequate imaging tests for screening asbestos-related diseases. We searched peer-reviewed publications, national and international technical documents, and specialists' opinions on the theme. Based on that, the major recommendations are: Individuals exposed to asbestos at the workplace for ≥ 1 year or those with a history of environmental exposure for at least 5 years, all of those with a latency period > 20 years from the date of initial exposure, should initially undego HRCT of the chest for investigation. Individuals with pleural disease and/or asbestosis should be considered for regular lung cancer monitoring. Risk calculators should be adopted for lung cancer screening, with a risk estimate of 1.5%.

Does Multidisciplinary Team Management Improve Clinical Outcomes in NSCLC? A Systematic Review With Meta-Analysis.

Introduction: The implementation of multidisciplinary teams (MDTs) has been found to be effective for improving outcomes in oncology. Nevertheless, there is still a dearth of robust literature on patients with NSCLC. The aim of this study was to conduct a systematic review regarding the impact of MDTs on patient with NSCLC outcomes. Methods: Databases were systematically searched up to February 2023. Two reviewers independently performed study selection and data extraction. Risk of bias was evaluated using the Newcastle-Ottawa and certainty of evidence by the Grading of Recommendations Assessment, Development and Evaluation approach. Overall survival was the primary outcome. Secondary outcomes included mortality, length of survival, progression-free survival, time from diagnosis to treatment, complete staging, treatment received, and adherence to guidelines. A meta-analysis with a random-effect model was performed. Statistical analysis was performed with the R 3.6.2 package. Results: A total of 22 studies were included in the systematic review. Ten outcomes were identified, favoring the MDT group over the non-MDT group. Pooled analysis revealed that patients managed by MDTs had better overall survival (three studies; 38,037 participants; hazard ratio 0.60, 95% confidence interval [CI]: 0.49-0.75, I2 = 78%), shorter treatment time compared with patients in the non-MDT group (six studies; 15,235 participants; mean difference = 12.20 d, 95% CI: 10.76-13.63, I2 = 63%), and higher proportion of complete staging (four studies; 14,925 participants; risk ratio = 1.36, 95% CI: 1.17-1.57, I2 = 89%). Conclusions: This meta-analysis revealed that MDT-based patient care was associated with longer overall survival and better quality-of-care-related outcomes.

The importance of the endothelial nitric oxide synthase on the release of 6-nitrodopamine from mouse isolated atria and ventricles and their role on chronotropism.

6-nitrodopamine (6-ND) is released from rat isolated atria, where it acts as a potent positive chronotropic agent. The release of 6-ND from rat isolated atria and ventricles is significantly reduced when pre-incubated with l-NAME, and the release was not affected by tetrodotoxin pre-treatment, indicating that in the heart, the origin of 6-ND is not neurogenic. Since l-NAME inhibits all three isoforms of NO synthase, it was investigated the basal release of 6-ND from isolated atria and ventricles from nNOS-/-, iNOS-/- and eNOS-/- mice of either sex. The release of 6-ND was measured by LC-MS/MS. There were no significant differences in the 6-ND basal release from isolated atria and ventricles from male control mice, as compared to female control mice. The 6-ND release from atria obtained from eNOS-/- mice was significantly reduced when compared to atria obtained from control mice. The 6-ND release in nNOS-/- mice was not significantly different compared to control animals whereas the 6-ND release from atria obtained from iNOS-/- mice was significantly higher when compared to control group. Incubation of the isolated atria with l-NAME caused a significant decrease in the basal atrial rate of control, nNOS-/-, and iNOS-/- mice, but not in eNOS-/- mice. The results clearly indicate that eNOS is the isoform responsible for the synthesis of 6-ND in the mice isolated atria and ventricles and supports the concept that 6-ND is the major mechanism by which endogenous NO modulates heart rate.

Morphological and topographic evaluation of the mandibular canal and its relationship with the facial profile, skeletal class, and sex.

PURPOSE: The aim of this study was to evaluate the morphology and topography of the mandibular canal in patients with different facial profiles, skeletal classes, and sexes. METHODS: Cone-beam computed tomography volumes of 103 patients were classified according to facial profile and skeletal class. Two examiners classified the mandibular canal into a linear, spoon-shaped, elliptical arc, or turning curvature and measured four related linear distances. The most frequent mandibular canal curvature was identified and multi-way ANOVA with Tukey's test compared the linear measurements between facial types, skeletal class, and sexes (α = 0.05). Kappa and intraclass correlation coefficients were used to assess the reproducibility of qualitative and quantitative variables, respectively. RESULTS: The examiners showed excellent reproducibility. The four curvatures of the mandibular canal were found, but the spoon-shaped and elliptical arch were the most frequent. No significant differences were observed for most of the linear measurements between the different facial profiles, skeletal classes, and sexes (p > 0.05). CONCLUSION: Spoon-shaped and elliptical arch are the most frequent curvatures of the mandibular canal; furthermore, its morphology and topography seem to be little influenced by the facial profile, skeletal class, and sex.

Ediacaran Corumbella has a cataphract calcareous skeleton with controlled biomineralization.

Corumbella is a terminal Ediacaran tubular, benthic fossil of debated morphology, composition, and biological affinity. Here, we show that Corumbella had a biomineralized skeleton, with a bilayered construction of imbricated calcareous plates and rings (sclerites) yielding a cataphract organization, that enhanced flexibility. Each sclerite likely possessed a laminar microfabric with consistent crystallographic orientation, within an organic matrix. Original aragonitic mineralogy is supported by relict aragonite and elevated Sr (mean = ca. 11,800 ppm in central parts of sclerites). In sum, the presence of a polarisation axis, sclerites with a laminar microfabric, and a cataphract skeletal organization reminiscent of early Cambrian taxa, are all consistent with, but not necessarily indicative of, a bilaterian affinity. A cataphract skeleton with an inferred complex microstructure confirms the presence of controlled biomineralization in metazoans by the terminal Ediacaran, and offers insights into the evolution of development and ecology at the root of the 'Cambrian radiation'.

Stereoselective Synthesis of Hydrindane and Hydroazulene Derivatives by Transannular Cyclization of Nine- and Ten-Membered Carbocycles.

Treatment of cis-fused bicyclic diene dicarboxylates with Li/naphthalene triggers a tandem ring-opening and transannular cyclization process that stereoselectively yields hydroazulenes and hydrindanes derivatives. Cyclononadienyl diesters, which can be isolated after the ring-opening step by judicious choice of the reaction conditions, undergo a tandem conjugate addition/intramolecular Michael addition upon treatment with chiral lithium amides to give bicyclic ß-amino esters in a process where 4 contiguous stereocenters are formed with high diastereocontrol. A concise route toward the highly enantioenriched AEF ring core of the aconitine-type alkaloids has been developed as an application of this methodology. The starting cis-fused bicyclic dicarboxylates are easily prepared in one step by reductive alkylation of diisopropyl phthalate (Na/THF, followed by the appropriate bis-electrophiles).

The role of volcanic-derived clays in the preservation of Ediacaran biota from the Itajaí Basin (ca. 563 Ma, Brazil).

The early evolution of metazoans has been reconstructed by studies on exceptionally preserved molds in siliciclastic rocks from the Ediacaran Period. However, there remains considerable controversy regarding the formation mechanisms of this unusual 'Ediacaran-style' preservation. Proposed hypotheses usually include early authigenesis of minerals, but evidence for this is scarce. In a recently discovered deposit of Ediacaran biota in Brazil, we show that the classic moldic preservation is related to clay mineral authigenesis. Specifically, these clays originated from the alteration of original pyroclastic sediments, likely enhanced by microbial activity, leading to early illitization and morphological templating of the fossiliferous surfaces at a micrometric scale. Such high-fidelity preservation was made possible by rapid burial during volcanic events and the in-situ templating of tissue by clays via microbially-mediated mineralization. This newly described Lagerstätte demonstrates that a number of minerals can facilitate preservation, and that perhaps 'Ediacaran-style' preservation result from different processes leading to the same broad style of preservation.

Machine learning model for predicting severity prognosis in patients infected with COVID-19: Study protocol from COVID-AI Brasil.

The new coronavirus, which began to be called SARS-CoV-2, is a single-stranded RNA beta coronavirus, initially identified in Wuhan (Hubei province, China) and currently spreading across six continents causing a considerable harm to patients, with no specific tools until now to provide prognostic outcomes. Thus, the aim of this study is to evaluate possible findings on chest CT of patients with signs and symptoms of respiratory syndromes and positive epidemiological factors for COVID-19 infection and to correlate them with the course of the disease. In this sense, it is also expected to develop specific machine learning algorithm for this purpose, through pulmonary segmentation, which can predict possible prognostic factors, through more accurate results. Our alternative hypothesis is that the machine learning model based on clinical, radiological and epidemiological data will be able to predict the severity prognosis of patients infected with COVID-19. We will perform a multicenter retrospective longitudinal study to obtain a large number of cases in a short period of time, for better study validation. Our convenience sample (at least 20 cases for each outcome) will be collected in each center considering the inclusion and exclusion criteria. We will evaluate patients who enter the hospital with clinical signs and symptoms of acute respiratory syndrome, from March to May 2020. We will include individuals with signs and symptoms of acute respiratory syndrome, with positive epidemiological history for COVID-19, who have performed a chest computed tomography. We will assess chest CT of these patients and to correlate them with the course of the disease. Primary outcomes:1) Time to hospital discharge; 2) Length of stay in the ICU; 3) orotracheal intubation;4) Development of Acute Respiratory Discomfort Syndrome. Secondary outcomes:1) Sepsis; 2) Hypotension or cardiocirculatory dysfunction requiring the prescription of vasopressors or inotropes; 3) Coagulopathy; 4) Acute Myocardial Infarction; 5) Acute Renal Insufficiency; 6) Death. We will use the AUC and F1-score of these algorithms as the main metrics, and we hope to identify algorithms capable of generalizing their results for each specified primary and secondary outcome.

In situ filamentous communities from the Ediacaran (approx. 563 Ma) of Brazil.

Precambrian filamentous microfossils are common and diverse. Nevertheless, their taxonomic assignment can be difficult owing to their overall simple shapes typically lacking in diagnostic features. Here, we report in situ communities of well-preserved, large filamentous impressions from the Ediacaran Itajaí Basin (ca 563 Ma) of Brazil. The filaments are uniserial (unbranched) and can reach up to 200 µm in width and up to 44 mm in length. They occur as both densely packed or sparsely populated surfaces, and typically show a consistent orientation. Although simple in shape, their preferred orientation suggests they were tethered to the seafloor, and their overall flexibility (e.g. bent, folded and twisted) supports a biological (rather than sedimentary) affinity. Biometric comparisons with modern filamentous groups further support their biological affinity, suggesting links with either large sulfide-oxidizing bacteria (SOB) or eukaryotes. Other morphological and palaeoecological characteristics further corroborates their similarities with modern large filamentous SOB. Their widespread occurrence and association with complex Ediacaran macrobiota (e.g. frondose organisms, Palaeopascichnus) suggest that they probably played an important role in the ecological dynamics of these early benthic communities by providing firm substrates for metazoans to inhabit. It is further hypothesized that the dynamic redox condition in the latest Ediacaran, with the non-continuous rise in oxygen concentration and periods of hypoxia, may have created ideal conditions for SOB to thrive.

Knowledge of and attitudes toward the WHO MPOWER policies to reduce tobacco use at the population level: a comparison between third-year and sixth-year medical students.

OBJECTIVE: To evaluate third- and sixth-year medical students in Brazil in terms of their knowledge of and attitudes toward the WHO MPOWER policies to reduce tobacco use. METHODS: The WHO Global Health Professions Student Survey was applied in five cohorts of medical students evaluated in their third and sixth years of medical school, between 2008 and 2015. Comparisons were drawn between the two years of medical school in terms of the proportions of students who experimented with or used tobacco products in the last 30 days prior to the survey; knowledge of and compliance with smoke-free policies on the university campus; formal training on smoking cessation strategies; and self-recognition as role models for patients/society. RESULTS: Of the 943 students who completed the survey, approximately 6% had smoked cigarettes in the last 30 days prior to the survey. Comparing the third and sixth years of medical school, we observed a significant increase in the proportion of students who were knowledgeable about smoking cessation strategies (22.74% vs. 95.84%; p < 0.001) and in that of those who recognized their role as models for patients/society (84.5% vs. 89.7%; p = 0.023). Student knowledge of the smoking policies on the university campus was associated with an increase in self-recognition as role models (adjusted absolute difference = 6.7%; adjusted p = 0.050). CONCLUSIONS: Knowledge of smoking cessation strategies and self-recognition as role models for patients/society increase over the course of medical school and are associated with the implementation of smoke-free policies.

Knowledge of and attitudes toward the WHO MPOWER policies to reduce tobacco use at the population level: a comparison between third-year and sixth-year medical students / Conhecimento e atitudes sobre as políticas MPOWER da OMS para redução do uso do tabaco em nível populacional: comparação entre estudantes de medicina do terceiro e sexto anos

ABSTRACT Objective: To evaluate third- and sixth-year medical students in Brazil in terms of their knowledge of and attitudes toward the WHO MPOWER policies to reduce tobacco use. Methods: The WHO Global Health Professions Student Survey was applied in five cohorts of medical students evaluated in their third and sixth years of medical school, between 2008 and 2015. Comparisons were drawn between the two years of medical school in terms of the proportions of students who experimented with or used tobacco products in the last 30 days prior to the survey; knowledge of and compliance with smoke-free policies on the university campus; formal training on smoking cessation strategies; and self-recognition as role models for patients/society. Results: Of the 943 students who completed the survey, approximately 6% had smoked cigarettes in the last 30 days prior to the survey. Comparing the third and sixth years of medical school, we observed a significant increase in the proportion of students who were knowledgeable about smoking cessation strategies (22.74% vs. 95.84%; p < 0.001) and in that of those who recognized their role as models for patients/society (84.5% vs. 89.7%; p = 0.023). Student knowledge of the smoking policies on the university campus was associated with an increase in self-recognition as role models (adjusted absolute difference = 6.7%; adjusted p = 0.050). Conclusions: Knowledge of smoking cessation strategies and self-recognition as role models for patients/society increase over the course of medical school and are associated with the implementation of smoke-free policies.

RESUMO Objetivo: Avaliar estudantes de medicina do terceiro e sexto anos no Brasil em relação a seu conhecimento e atitudes sobre as políticas MPOWER da OMS para redução do uso do tabaco. Métodos: A Pesquisa Global de Estudantes de Profissões da Saúde da OMS foi aplicada em cinco coortes de estudantes de medicina avaliados no terceiro e sexto anos da graduação, entre 2008 e 2015. Foram feitas comparações entre os dois anos da graduação em relação às proporções de estudantes que experimentaram ou fizeram uso de produtos de tabaco nos últimos 30 dias antes da pesquisa; conhecimento e cumprimento das políticas antifumo no campus universitário; treinamento formal sobre estratégias de cessação do tabagismo; e autorreconhecimento como modelo de comportamento para pacientes/sociedade. Resultados: Dos 943 estudantes que preencheram a pesquisa, aproximadamente 6% haviam fumado cigarro nos últimos 30 dias antes da pesquisa. Ao compararmos o terceiro e sexto anos da graduação, observamos um aumento significativo na proporção de estudantes que tinham conhecimento sobre estratégias de cessação do tabagismo (22,74% vs. 95,84%; p < 0,001) e na daqueles que reconheciam seu papel como modelo para pacientes/sociedade (84,5% vs. 89,7%; p = 0,023). O conhecimento dos estudantes sobre as políticas de tabagismo existentes no campus universitário associou-se ao aumento no autorreconhecimento como modelo de comportamento (diferença absoluta ajustada = 6,7%; p ajustado = 0,050). Conclusões: O conhecimento sobre estratégias de cessação do tabagismo e a autorreconhecimento como modelo de comportamento para pacientes/sociedade aumentaram ao longo da graduação e estão associados à implementação de políticas antifumo.

Neuronal Plasma Membrane Integrity is Transiently Disturbed by Traumatic Loading.

The acute response of neurons subjected to traumatic loading involves plasma membrane disruption, yet the mechanical tolerance for membrane compromise, time course, and mechanisms for resealing are not well understood. We have used an in vitro traumatic neuronal injury model to investigate plasma membrane integrity immediately following a high-rate shear injury. Cell-impermeant fluorescent molecules were added to cortical neuronal cultures prior to insult to assess membrane integrity. The percentage of cells containing the permeability marker was dependent on the molecular size of the marker, as smaller molecules gained access to a higher percentage of cells than larger ones. Permeability increases were positively correlated with insult loading rate. Membrane disruption was transient, evidenced by a membrane resealing within the first minute after the insult. In addition, chelation of either extracellular Ca2+ or intracellular Ca2+ limited membrane resealing. However, injury following chelation of both extracellular and intracellular Ca2+ caused diminished permeability as well as a greater resealing ability compared to chelation of extracellular or intracellular Ca2+ alone. Treatment of neuronal cultures with jasplakinolide, which stabilizes filamentous actin, reduced permeability increases, while latrunculin-B, an actin depolymerizing agent, both reduced the increase in plasma membrane permeability and promoted resealing. This study gives insight into the dynamics of neuronal membrane disruption and subsequent resealing, which was found to be calcium dependent and involve actin in a role that differs from non-neuronal cells. Taken together, these data will lead to a better understanding of the acute neuronal response to traumatic loading.

Chemical characterization of pterosaur melanin challenges color inferences in extinct animals.

Melanosomes (melanin-bearing organelles) are common in the fossil record occurring as dense packs of globular microbodies. The organic component comprising the melanosome, melanin, is often preserved in fossils, allowing identification of the chemical nature of the constituent pigment. In present-day vertebrates, melanosome morphology correlates with their pigment content in selected melanin-containing structures, and this interdependency is employed in the color reconstruction of extinct animals. The lack of analyses integrating the morphology of fossil melanosomes with the chemical identification of pigments, however, makes these inferences tentative. Here, we chemically characterize the melanin content of the soft tissue headcrest of the pterosaur Tupandactylus imperator by alkaline hydrogen peroxide oxidation followed by high-performance liquid chromatography. Our results demonstrate the unequivocal presence of eumelanin in T. imperator headcrest. Scanning electron microscopy followed by statistical analyses, however, reveal that preserved melanosomes containing eumelanin are undistinguishable to pheomelanin-bearing organelles of extant vertebrates. Based on these new findings, straightforward color inferences based on melanosome morphology may not be valid for all fossil vertebrates, and color reconstructions based on ultrastructure alone should be regarded with caution.

C-C Bond-Forming and Bond-Breaking Processes from the Reaction of Diesters with Me3SnLi. Synthesis of Complex Bridged Polycycles and Dialkyl Aromatic Compounds.

1,2-Aromatic diesters can be transformed into strained bridged polycyclic structures by a two-step procedure consisting of an initial reductive alkylation promoted by alkaline metals, followed by a reaction of the resulting unsaturated diesters with Me3SnLi. We propose that a stanna-Brook rearrangement plays a fundamental role in the formation of the polycyclic organotin acetals obtained. These unusual compounds could be further functionalized by tin-lithium exchange followed by alkylation of the newly formed tertiary carbanion. Alternatively, dialkylated aromatic hydrocarbons have been prepared via a decarbonilation reaction promoted by Me3SnLi. 1,4-Aromatic diesters were reductively dialkylated and then transformed into norbornadienone derivatives by reaction with Me3SnLi. Several stable dibenzonorbornadienones 41 have been prepared in just two steps starting from anthracene 38. The corresponding naphthalene analogues gave 1,4-dialkylnaphthalenes. The synthetic protocols described provide access to structures that are not easily obtained through existing synthetic methodologies.

Mechanoporation is a potential indicator of tissue strain and subsequent degeneration following experimental traumatic brain injury.

BACKGROUND: An increases in plasma membrane permeability is part of the acute pathology of traumatic brain injury and may be a function of excessive membrane force. This membrane damage, or mechanoporation, allows non-specific flux of ions and other molecules across the plasma membrane, and may ultimately lead to cell death. The relationships among tissue stress and strain, membrane permeability, and subsequent cell degeneration, however, are not fully understood. METHODS: Fluorescent molecules of different sizes were introduced to the cerebrospinal fluid space prior to injury and animals were sacrificed at either 10 min or 24 h after injury. We compared the spatial distribution of plasma membrane damage following controlled cortical impact in the rat to the stress and strain tissue patterns in a 3-D finite element simulation of the injury parameters. FINDINGS: Permeable cells were located primarily in the ipsilateral cortex and hippocampus of injured rats at 10 min post-injury; however by 24 h there was also a significant increase in the number of permeable cells. Analysis of colocalization of permeability marker uptake and Fluorojade staining revealed a subset of permeable cells with signs of degeneration at 24 h, but plasma membrane damage was evident in the vast majority of degenerating cells. The regional and subregional distribution patterns of the maximum principal strain and shear stress estimated by the finite element model were comparable to the cell membrane damage profiles following a compressive impact. INTERPRETATION: These results indicate that acute membrane permeability is prominent following traumatic brain injury in areas that experience high shear or tensile stress and strain due to differential mechanical properties of the cell and tissue organization, and that this mechanoporation may play a role in the initiation of secondary injury, contributing to cell death.