Micromechanical modelling of short fibre composites considering fibre length distributions

Mechanical response of short fibre composites is varying locally with respect to the microstructural constitution of the material, which in turn is a consequence of flow conditions during manufacturing. This local constitution is described by local fibre volume content, local fibre orientation distribution and local fibre length distribution. For short fibre reinforced plastics, both distributions are affected by flow conditions during an injection moulding process. Current material models for predicting the homogenised material response account for the local volume fraction and local fibre orientation distribution. Fibre length distribution, however, is usually approximated with a single average fibre length. To investigate the effects of fibre length distribution on the elasto-plastic response of short fibre composites, a micromechanical Orientation Averaging model has been extended. Two methods are presented in this work. In the first method, an additional averaging scheme over the fibre length distribution is included. In the second method, a novel representative fibre length is presented based on a stiffness-weighted average. The predictionsobtained from these methods are then compared and evaluated against experimental results of uniaxial tensile tests taken from literature. Good agreements are found using both methods. However, for the investigated behaviour, using a representative fibre length is still beneficial due to the superior computational performance

Character and environmental lability of cyanobacteria-derived dissolved organic matter

Autotrophic dissolved organic matter (DOM) is central to the carbon biogeochemistry of aquatic systems, and the full complexity of autotrophic DOM has not been extensively studied, particularly by high-resolution mass spectrometry (HRMS). Terrestrial DOM tends to dominate HRMS studies in freshwaters due to the propensity of such compounds to ionize by negative mode electrospray, and possibly also because ionizable DOM produced by autotrophy is decreased to low steady-state concentrations by heterotrophic bacteria. In this study, we investigated the character of DOM produced by the widespread cyanobacteriaMicrocystis aeruginosausing high-pressure liquid chromatography-electrospray ionization-high-resolution mass spectrometry.M. aeruginosaproduced thousands of detectable compounds in axenic culture. These compounds were chromatographically resolved and the majority were assigned to aliphatic formulas with a broad polarity range. We found that the DOM produced byM. aeruginosawas highly susceptible to removal by heterotrophic freshwater bacteria, supporting the hypothesis that this autotroph-derived organic material is highly labile and accordingly only seen at low concentrations in natural settings

Follow-up of patients with curatively resected colorectal cancer: a practice guideline

BACKGROUND: A systematic review was conducted to evaluate the literature regarding the impact of follow-up on colorectal cancer patient survival and, in a second phase, recommendations were developed. METHODS: The MEDLINE, CANCERLIT, and Cochrane Library databases, and abstracts published in the 1997 to 2002 proceedings of the annual meeting of the American Society of Clinical Oncology were systematically searched for evidence. Study selection was limited to randomized trials and meta-analyses that examined different programs of follow-up after curative resection of colorectal cancer where five-year overall survival was reported. External review by Ontario practitioners was obtained through a mailed survey. Final approval of the practice guideline report was obtained from the Practice Guidelines Coordinating Committee. RESULTS: Six randomized trials and two published meta-analyses of follow-up were obtained. Of six randomized trials comparing one follow-up program to a more intense program, only two individual trials detected a statistically significant survival benefit favouring the more intense follow-up program. Pooling of all six randomized trials demonstrated a significant improvement in survival favouring more intense follow-up (Relative Risk Ratio 0.80 (95%CI, 0.70 to 0.91; p = 0.0008). Although the rate of recurrence was similar in both of the follow-up groups compared, asymptomatic recurrences and re-operations for cure of recurrences were more common in patients with more intensive follow-up. Trials including CEA monitoring and liver imaging also had significant results, whereas trials not including these tests did not. CONCLUSION: Follow-up programs for patients with curatively resected colorectal cancer do improve survival. These follow-up programs include frequent visits and performance of blood CEA, chest x-rays, liver imaging and colonoscopy, however, it is not clear which tests or frequency of visits is optimal. There is a suggestion that improved survival is due to diagnosis of recurrence at an earlier, asymptomatic stage which allows for more curative resection of recurrence. Based on this evidence and consideration of the biology of colorectal cancer and present practices, a guideline was developed. Patients should be made aware of the risk of disease recurrence or second bowel cancer, the potential benefits of follow-up and the uncertainties requiring further clinical trials. For patients at high-risk of recurrence (stages IIb and III) clinical assessment is recommended when symptoms occur or at least every 6 months the first 3 years and yearly for at least 5 years. At the time of those visits, patients may have blood CEA, chest x-ray and liver imaging. For patients at lower risk of recurrence (stages I and Ia) or those with co-morbidities impairing future surgery, only visits yearly or when symptoms occur. All patients should have a colonoscopy before or within 6 months of initial surgery, and repeated yearly if villous or tubular adenomas >1 cm are found; otherwise repeat every 3 to 5 years. All patients having recurrences should be assessed by a multidisciplinary team in a cancer centre

Transanal endoscopic microsurgery versus endoscopic mucosal resection for large rectal adenomas (TREND-study)

Background: Recent non-randomized studies suggest that extended endoscopic mucosal resection (EMR) is equally effective in removing large rectal adenomas as transanal endoscopic microsurgery (TEM). If equally effective, EMR might be a more cost-effective approach as this strategy does not require expensive equipment, general anesthesia and hospital admission. Furthermore, EMR appears to be associated with fewer complications. The aim of this study is to compare the cost-effectiveness and cost-utility of TEM and EMR for the resection of large rectal adenomas. Methods/design. Multicenter randomized trial among 15 hospitals in the Netherlands. Patients with a rectal adenoma 3 cm, located between 115 cm ab ano, will be randomized to a TEM- or EMR-treatment strategy. For TEM, patients will be treated under general anesthesia, adenomas will be dissected en-bloc by a full-thickness excision, and patients will be admitted to the hospital. For EMR, no or conscious sedation is used, lesions will be resected through the submucosal plane i

Protocolo eletrônico de coleta de dados clínicos da microcirurgia endoscópica transanal (TEM): desenvolvimento e aplicação Electronic protocol of clinical data collection in transanal endoscopic microsurgery (TEM): development and application

INTRODUÇÃO: A coleta de dados na forma prospectiva melhora a assistência ao paciente e o acesso à informação. Os registros feitos em prontuários de papel geralmente não trazem informação satisfatória, pois os dados acabam sendo perdidos ou não coletados adequadamente. A informática na saúde possibilita o melhor uso da informação, servindo, inclusive, como suporte para pesquisas científicas. OBJETIVOS: 1 - Criar, informatizar e armazenar uma base de dados clínicos da Microcirurgia Endoscópica Transanal (TEM), incorporando-a ao SINPE© e realizando coleta de dados; 2 - apresentar estudo descritivo dos resultados da coleta de dados realizada em 59 pacientes submetidos a TEM. MÉTODOS: Primeiro foi realizada a criação da base teórica de dados da TEM, que foi a seguir informatizada e incorporando-a ao SINPE© e realizou-se a coleta de dados. Segundo, efetuou-se estudo descritivo com interpretação das informações obtidas através de estatísticas e gráficos pelo módulo SINPE©Analisador. RESULTADOS: A utilização do software possibilitou a criação do protocolo da TEM. Os dados armazenados pela coleta de 59 pacientes submetidos ao procedimento cirúrgico foram resgatados e analisados pelo módulo SINPE Analisador©, gerando gráficos e estudos descritivos automaticamente. Verificou-se que 74,55% (41) dos pacientes apresentavam, antes do procedimento operatório, o diagnóstico de adenoma. No estadiamento pré-operatório realizado por ultrassonografia transrretal, notou-se que a maioria dos tumores apresentaram estadiamento pré-operatório de adenoma (uT0). Em relação ao acometimento linfonodal dois foram avaliados no ultrassom como comprometidos. Quanto à profundidade de ressecção da parede retal verificou-se que mais de 60% dos pacientes submetidos à TEM realizaram ressecção em bloco de toda a parede retal, ou seja, até a gordura perirretal. Verificou-se, que o número total de pacientes portadores de adenocarcinoma foi maior no estudo histopatológico da peça cirúrgica que na biópsia pré-operatória. Os resultados do estadiamento histopatológico da peça cirúrgica apresentou diferenças entre o estadiamento pré-operatório e pós-operatório. A presença de carcinoma incidental em pacientes que possuíam diagnóstico pré-operatório de adenoma, foi de 13 (31,7%). Realizou-se avaliação dos pacientes portadores de adenocarcinoma que foram submetidos à ressecção em bloco da parede retal, ou seja, até a gordura perirretal. Foram diagnosticados, no exame histológico pós-operatório, 22 pacientes (37,28% dos pacientes submetidos à TEM) portadores de adenocarcinoma. Destes 19 foram submetidos à ressecção até a gordura perirretal (86,36% dos pacientes portadores de adenocarcinoma). O estadiamento realizado pela ultrassonografia transrretal demonstrou 24 tumores uT0. No exame histopatológico das peças cirúrgicas, observou-se que 11 apresentavam adenoma, nove carcinoma in situ, ou seja, dos 24 tumores estadiados em uT0, 20 apresentaram estadiamento pós-operatório compatível o exame pré-operatório (83,33%). CONCLUSÕES: O software SINPE© representou ferramenta adequada à pesquisa clínica e contribuiu com o levantamento preciso e fácil dos dados coletados em pesquisa prospectiva.<br>BACKGROUND: Prospective data collection improves patient care and information access. Written medical records frequently are not well done, due to bad collected data associated to the risk of loosing important items. The use of computer technology in health care system provides better information. OBJECTIVES: To create, computerize and store a clinical database to Transanal Endoscopic Microsurgery (TEM), and it´s incorporation into SINPE© software; to present a descriptive study from 59 patients submitted to TEM. METHODS: Initially was created an Word® questionnaire containing all clinical data concerning to TEM; afterwards, this base was computerized and incorporated into SINPE© and, then, data started to be collected. Later, a descriptive study was done using the database with statistic analysis generated through SINPE©Analisador module. Finally, datamining studies verified patterns and tendencies which could not be visualized from simple data collection. RESULTS: The software allowed creation of TEM protocol. The data stored by collecting 59 patients undergoing the surgical procedure were recovered and analyzed by SINPE©Analisador module, generating charts and statistic automatically. It was found that 74.55% (41) of the patients presented with the diagnosis of adenoma before the surgical procedure. Preoperative staging conducted by transrectal ultrasonography defined most tumors as adenomas (uT0). Ultrasound identified that two lymph nodes were involved. With regard to the depth of the rectal wall resection, it was found that over 60% of the patients who underwent TEM had a full-thickness resection of all rectal wall, i.e., up to the peri-rectal fat. The total number of adenocarcinoma patients was greater in the histopathological study of the surgical specimen than in the preoperative biopsy. The results for the histopathological staging of the surgical specimen revealed differences between pre- and postoperative staging. Incidental carcinoma was present in 13 (31.7%) patients with a preoperative diagnosis of adenoma. An evaluation was conducted of the adenocarcinoma patients who underwent the full-thickness resection of the rectal wall. Postoperative histological review diagnosed 22 patients (37.28% of the patients submitted to TEM) with adenocarcinoma. Of these, 19 underwent resection up to the peri-rectal fat (86.36% of the adenocarcinoma patients). The staging carried out through transrectal ultrasonography identified 24 uT0 tumors. The histopathological examinatin of the surgical specimens showed that 11 were adenomas and nine were carcinomas in situ. Thus, 20 (83.33%) of the 24 tumors that had been staged as uT0 presented a postoperative staging consistent with the preoperative assessment. CONCLUSIONS: SINPE© software is an adequate tool for clinical research and contributed to the accurate and easy management of the prospectively collected data