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Silk fiber, recognized as a versatile bioresource, holds wide-ranging significance in agriculture and the textile industry. During the breeding of silkworms to yield new varieties, optical sensing techniques have been employed to distinguish the colors of silk cocoons, aiming to assess their improved suitability across diverse industries. Despite visual comparison retaining its primary role in differentiating colors among a range of silk fibers, the presence of uneven surface texture leads to color distortion and inconsistent color perception at varying viewing angles. As a result, these distorted and inconsistent visual assessments contribute to unnecessary fiber wastage within the textile industry. To solve these issues, we have devised an optical system employing an integrating sphere to deliver consistent and uniform illumination from all orientations. Utilizing a ColorChecker, we calibrated the RGB values of silk cocoon images taken within the integrating sphere setup. This process accurately extracts the authentic RGB values of the silk cocoons. Our study not only helps in unraveling the intricate color of silk cocoons but also presents a unique approach applicable to various specimens with uneven surface textures.
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Bombyx , Seda , Animais , Seda/químicaRESUMO
Epidemiologic studies of the short-term effects of ambient particulate matter (PM) on the risk of acute cardiovascular or cerebrovascular events often use data from administrative databases in which only the date of hospitalization is known. A common study design for analyzing such data is the case-crossover design, in which exposure at a time when a patient experiences an event is compared to exposure at times when the patient did not experience an event within a case-control paradigm. However, the time of true event onset may precede hospitalization by hours or days, which can yield attenuated effect estimates. In this article, we consider a marginal likelihood estimator, a regression calibration estimator, and a conditional score estimator, as well as parametric bootstrap versions of each, to correct for this bias. All considered approaches require validation data on the distribution of the delay times. We compare the performance of the approaches in realistic scenarios via simulation, and apply the methods to analyze data from a Boston-area study of the association between ambient air pollution and acute stroke onset. Based on both simulation and the case study, we conclude that a two-stage regression calibration estimator with a parametric bootstrap bias correction is an effective method for correcting bias in health effect estimates arising from delayed onset in a case-crossover study.
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Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/efeitos adversos , Poluição do Ar/análise , Viés , Estudos Cross-Over , Exposição Ambiental , Humanos , Material ParticuladoRESUMO
OBJECTIVE: The aim of this study was to investigate the survival, patterns of failure, and prognostic factors in patients with stage II endometrial carcinoma treated with adjuvant radiotherapy. METHODS: We reviewed the medical records of patients who underwent total hysterectomy, bilateral salpingo-oophorectomy, and pelvic lymph node dissection followed by adjuvant radiotherapy in 10 participating hospitals of the Korean Radiation Oncology Group. Most patients received adjuvant external beam radiation therapy, with a median dose of 50.4 Gy; approximately 50% of these patients received an additional brachytherapy boost, with a median dose of 18 Gy. Adjuvant chemotherapy was administered to 19 patients. RESULTS: A total of 122 patients were examined. Over a median follow-up period of 62.7 months (range, 1.9-158.8 months), the 5-year overall survival (OS) and disease-free survival rates were found to be 91.1% and 85.1%, respectively. Recurrence was observed in 14 patients (11.5%), including 3 with local recurrence and 11 with distant metastases as the first site of recurrence. Univariate analysis indicated that lymphovascular invasion was related to an unfavorable OS. An age of 60 years or above, histologic grade 3, and lymphovascular invasion were identified as risk factors for OS. Because there were several risk factors related to OS, we assigned patients to a high-risk group (defined as cases with ≥1 risk factors) and a low-risk group. The 5-year OS rate of the high-risk group was significantly inferior to that of the low-risk group (82.9% vs 100%, P = 0.003). CONCLUSIONS: The high-risk group had a significantly poorer survival rate than the low-risk group, and distant metastasis was the main pattern of recurrence, thus indicating that further adjuvant chemotherapy should be considered in high-risk patients.
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Neoplasias do Endométrio/radioterapia , Neoplasias do Endométrio/cirurgia , Adulto , Idoso , Neoplasias do Endométrio/patologia , Feminino , Humanos , Histerectomia , Excisão de Linfonodo , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Prognóstico , Radioterapia Adjuvante , Estudos Retrospectivos , Salpingo-Ooforectomia , Resultado do TratamentoRESUMO
Alzheimer's disease (AD) is usually diagnosed by clinicians through cognitive and functional performance test with a potential risk of misdiagnosis. Since the progression of AD is known to cause structural changes in the corpus callosum (CC), the CC thickness can be used as a functional covariate in AD classification problem for a diagnosis. However, misclassified class labels negatively impact the classification performance. Motivated by AD-CC association studies, we propose a logistic regression for functional data classification that is robust to misdiagnosis or label noise. Specifically, our logistic regression model is constructed by adopting individual intercepts to functional logistic regression model. This approach enables to indicate which observations are possibly mislabeled and also lead to a robust and efficient classifier. An effective algorithm using MM algorithm provides simple closed-form update formulas. We test our method using synthetic datasets to demonstrate its superiority over an existing method, and apply it to differentiating patients with AD from healthy normals based on CC from MRI.
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Doença de Alzheimer/diagnóstico , Modelos Logísticos , Algoritmos , Doença de Alzheimer/classificação , Corpo Caloso/patologia , Humanos , Imageamento por Ressonância MagnéticaRESUMO
Genome-wide association studies (GWAS) routinely apply principal component analysis (PCA) to infer population structure within a sample to correct for confounding due to ancestry. GWAS implementation of PCA uses tens of thousands of single-nucleotide polymorphisms (SNPs) to infer structure, despite the fact that only a small fraction of such SNPs provides useful information on ancestry. The identification of this reduced set of ancestry-informative markers (AIMs) from a GWAS has practical value; for example, researchers can genotype the AIM set to correct for potential confounding due to ancestry in follow-up studies that utilize custom SNP or sequencing technology. We propose a novel technique to identify AIMs from genome-wide SNP data using sparse PCA. The procedure uses penalized regression methods to identify those SNPs in a genome-wide panel that significantly contribute to the principal components while encouraging SNPs that provide negligible loadings to vanish from the analysis. We found that sparse PCA leads to negligible loss of ancestry information compared to traditional PCA analysis of genome-wide SNP data. We further demonstrate the value of sparse PCA for AIM selection using real data from the International HapMap Project and a genomewide study of inflammatory bowel disease. We have implemented our approach in open-source R software for public use.
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Estudo de Associação Genômica Ampla , Grupos Populacionais/genética , Análise de Componente Principal , Algoritmos , Mapeamento Cromossômico/métodos , Biologia Computacional/métodos , Variação Genética , Genética Populacional , Projeto HapMap , Humanos , Doenças Inflamatórias Intestinais/genética , Modelos Estatísticos , Polimorfismo de Nucleotídeo Único , Análise de Regressão , SoftwareRESUMO
We study a three-player Tullock contest in an endogenous-timing framework, focusing on the players' decisions on timing of effort exertion. In this model, there are two points in time at which the players may choose their effort levels. The players decide independently and announce simultaneously when they each will expend their effort, and then each player chooses her effort level at the point in time which she announced. We find that, given moderate asymmetries among the players, each of the players announces the first point in time, and thus they all choose their effort levels simultaneously at the first point in time. This finding is in sharp contrast to a well-known result obtained from two-player asymmetric contests with endogenous timing.
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In 2019, an outbreak of Spodoptera frugiperda (Smith) was first reported in Korea. This study aimed to determine the growth rate and feeding amount of S. frugiperda by temperature to establish the right time window for its control and management. Linear regression analysis was used to determine the growth period and thermal requirements of S. frugiperda. The longest growth period of 97.2 ± 1.2 days was observed at 16 °C, and the shortest growth period of 15.5 ± 0.7 days was observed at 36 °C. In terms of each growth stage, the pupal period was the longest at all temperatures, followed by the egg period. The maximum corn leaf feeding amount (6.61 g) was observed for the larvae grown at 16 °C, and the minimum (2.9 g) was observed at 36 °C. However, the daily feeding amount of S. frugiperda larvae was the highest at 28 °C and 32 °C. The hatching rate according to temperature exceeded 70% at 24 °C, 28 °C, and 32 °C, and the survival rate of larvae and pupae was 100% at 24 °C to 32 °C. Based on these results, a temperature range of 28 °C to 32 °C is proposed as the optimum temperature for the growth of S. frugiperda.
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When synthesizing nanoparticles in the liquid phase, polymeric materials (mainly polyvinylpyrrolidone, PVP) are applied as capping and/or stabilizing agents. The polymer layer on the nanoparticles must likely be removed since it blocks the active sites of the catalyst and inhibits mass transfer of the reactants. However, we have found that the polymer can have a positive effect on the direct synthesis of hydrogen peroxide. By testing Pd/SiO2 catalysts with different amounts of PVP, it was revealed that an adequate amount of PVP resulted in a higher rate of hydrogen peroxide production (1001 mmolH2O2 gPd -1 h-1) than pristine Pd/SiO2 did (750 mmolH2O2 gPd -1 h-1), unlike other PVP added Pd/SiO2 catalysts containing excess PVP (less than 652 mmolH2O2 gPd -1 h-1). The effect of PVP on the catalysts was examined by transmission electron microscopy, Fourier transform infrared spectroscopy, CO chemisorption, thermogravimetric analysis, and X-ray photoelectron spectroscopy. For the catalysts containing PVP, the oxidation state of the palladium 3d shifted to high binding energy due to electron transfer from Pd to the PVP molecules. Consequently, the presence of PVP on the catalysts inhibited oxygen dissociation and decomposition of the produced hydrogen peroxide, resulting in a high selectivity and high production rate of hydrogen peroxide.
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Upbeat nystagmus is known to be caused by an imbalance of the vertical vestibulo-ocular reflex (VOR), favoring downward VOR activity, due to bilateral lesions of the medulla, ventral tegmentum, anterior cerebellar vermis, adjacent brachium conjunctivum and the midbrain. We report on two patients who had transient upbeat nystagmus due to unilateral pontine infarction that may have disrupted bilateral upward VOR pathways running in the ventral tegmental tracts.
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Infartos do Tronco Encefálico/complicações , Infartos do Tronco Encefálico/patologia , Lateralidade Funcional , Nistagmo Patológico/etiologia , Ponte/patologia , Idoso , Eletronistagmografia/métodos , Humanos , Angiografia por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-IdadeAssuntos
Cefaleia/diagnóstico , Hipertensão Intracraniana/diagnóstico , Imageamento por Ressonância Magnética/métodos , Nervo Óptico/diagnóstico por imagem , Nervo Óptico/patologia , Ultrassonografia/métodos , Adulto , Cefaleia/etiologia , Humanos , Hipertensão Intracraniana/complicações , MasculinoRESUMO
The attenuation and immunoenhancing effects of rpoS and phoP Salmonella enterica serovar strain Typhi (Salmonella typhi) mutants have not been compared. Here, three S. typhi deletion mutants (phoP, rpoS, and rpoS-phoP double mutant) are constructed and these mutants are characterized with respect to invasiveness, virulence, and protective immune response compared with wild-type Ty2. It was found that phoP and phoP-rpoS deletion mutants are less invasive to HT-29 cells than the wild-type Ty2 and the rpoS single-deleted strain. The LD(50) of immunized mice was higher for phoP than for rpoS mutants, and the highest for the phoP-rpoS double mutant. In addition, all S. typhi mutants showed an increase in the specific serum IgG levels and T-cell-mediated immunity, and showed equal protection abilities against a wild-type Ty2 challenge after two rounds of immunization in BALB/c mice. It is concluded that phoP genes appear to play a more important role than rpoS genes in both cellular invasion and virulence of S. typhi, but not in immunogenicity in mice. Furthermore, the data indicate that the phoP-rpoS double mutant may show promise as a candidate for an attenuated typhoid vaccine.
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Proteínas de Bactérias/genética , Salmonella typhi/imunologia , Fator sigma/genética , Vacinas Tíficas-Paratíficas/imunologia , Animais , Anticorpos Antibacterianos/sangue , Linhagem Celular Tumoral , Proliferação de Células , Feminino , Deleção de Genes , Humanos , Imunoglobulina G/sangue , Dose Letal Mediana , Camundongos , Camundongos Endogâmicos BALB C , Mutagênese Insercional , Salmonella typhi/genética , Salmonella typhi/patogenicidade , Análise de Sobrevida , Linfócitos T/imunologia , Febre Tifoide/imunologia , Febre Tifoide/prevenção & controle , Vacinas Tíficas-Paratíficas/genética , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologia , VirulênciaRESUMO
SUMMARY: ArrayXPath (http://www.snubi.org/software/ArrayXPath/) is a web-based service for mapping and visualizing microarray gene-expression data with integrated biological pathway resources using Scalable Vector Graphics (SVG). Deciphering the crosstalk among pathways and integrating biomedical ontologies and knowledge bases may help biological interpretation of microarray data. ArrayXPath is empowered by integrating gene-pathway, disease-pathway, drug-pathway and pathway-pathway correlations with integrated Gene Ontology, Medical Subject Headings and OMIM Morbid Map-based annotations. We applied Fisher's exact test and relative risk to evaluate the statistical significance of the correlations. ArrayXPath produces Javascript-enabled SVGs for web-enabled interactive visualization of gene-expression profiles integrated with gene-pathway-disease interactions enriched by biomedical ontologies.
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Gráficos por Computador , Perfilação da Expressão Gênica/métodos , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Software , Análise por Conglomerados , Bases de Dados Genéticas , Predisposição Genética para Doença , Internet , Medical Subject Headings , Integração de Sistemas , Interface Usuário-ComputadorRESUMO
We investigated the limits and extent of lubricants biodegradation at different nutrient conditions and evaluated several soil biological activities with regard to their usefulness for monitoring the bioremediation process in a soil contaminated with lubricants. To examine the effects of nutrient addition on lubricants biodegradation, a bench-scale investigation was conducted under different nutrient conditions for over 105 days testing period. When nutrients were added to contaminated soil with aged lubricant, great stimulation was occurred in fertilized soil for hydrocarbon degradation activity compared to non-fertilized soil. At the end of the experiment (105 days after), the initial level of contamination (9320+/-343 mg/kg) was reduced by 42-51% in the fertilized soil, whereas, only 18% of the hydrocarbon was eliminated in the non-fertilized soil. The effect of biostimulation of indigenous soil microorganisms declined with time, apparently 42% of the initial concentration of hydrocarbon remained at the end of experiment. Lubricants biodegradation process could be monitored well by soil biological parameters. In fertilized soil, biological parameters (number of HUB, soil respiration, dehydrogenase and catalase activities) were significantly enhanced and correlated with each other, as well as the residual lubricant concentration.
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Biodegradação Ambiental , Hidrocarbonetos/metabolismo , Resíduos Industriais , Poluentes do Solo/metabolismo , Lubrificação , Microbiologia do SoloRESUMO
OBJECTIVE: The purpose of this study was to evaluate the prognosis according to the number of high risk factors in patients with high risk factors after radical hysterectomy and adjuvant chemoradiation therapy for early stage cervical cancer. METHODS: Clinicopathological variables and clinical outcomes of patients with FIGO (International Federation of Gynecology and Obstetrics) stage IB1 to IIA cervical cancer who had one or more high risk factors after radical hysterectomy and adjuvant chemoradiation therapy were retrospectively analyzed. Patients were divided into two groups according to the number of high risk factors (group 1, single high risk factor; group 2, two or more high risk factors). RESULTS: A total of 93 patients were enrolled in the present study. Forty nine out of 93 (52.7%) patients had a single high risk factor, and 44 (47.3%) had two or more high risk factors. Statistically significant differences in stage and stromal invasion were observed between group 1 and group 2. However, age, histology, tumor size, and lymphovascular space invasion did not differ significantly between the groups. Distant recurrence occurred more frequently in group 2, and the probability of recurrence and death was higher in group 2. CONCLUSION: Patients with two or more high risk factors had worse prognosis in early stage cervical cancer. For these patients, consideration of new strategies to improve survival may be worthwhile. Conduct of further clinical trials is warranted for development of adjuvant treatment strategies individualized to each risk group.
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Although statins, or hydroxymethylglutaryl coenzyme A (HMG-Co A) reductase inhibitors, are generally used to decrease levels of circulating cholesterol, they have also been reported to have neuroprotective effects through various mechanisms. However, recent results have indicated that they may be harmful in patients with amyotrophic lateral sclerosis (ALS). In this study, we investigate whether atorvastatin protects motor neuron-like cells (NSC-34D) from oxidative stress. To evaluate the effects of atorvastatin or hydrogen peroxide or both on NSC-34D cells, the cells were treated with various combinations of these agents. To evaluate the viability of the cells, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays and trypan blue staining were performed. Levels of free radicals and intracellular signaling proteins were evaluated using the fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and Western blotting, respectively. Atorvastatin protected NSC-34D cells against oxidative stress in a concentration-dependent manner. This neuroprotective effect of atorvastatin was blocked by LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor and by FR180204, a selective extracellular signal-related kinase (ERK) inhibitor. Atorvastatin treatment increased the expression levels of p85αPI3K, phosphorylated Akt, phosphorylated glycogen synthase kinase-3ß, phosphorylated ERK, and Bcl-2, which are proteins related to survival. Furthermore, atorvastatin decreased the levels of cytosolic cytochrome C, Bax, cleaved caspase-9, and cleaved caspase-3, which are associated with death in oxidative stress-injured NSC-34D cells. We conclude that atorvastatin has a protective effect against oxidative stress in motor neurons by activating the PI3K and ERK pathways as well as by scavenging free radicals. These findings indicate that statins could help protect motor neurons from oxidative stress.
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Atorvastatina/farmacologia , Sequestradores de Radicais Livres/metabolismo , Sistema de Sinalização das MAP Quinases/fisiologia , Neurônios Motores/metabolismo , Estresse Oxidativo/fisiologia , Fosfatidilinositol 3-Quinases/metabolismo , Animais , Antioxidantes/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Radicais Livres/antagonistas & inibidores , Radicais Livres/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Camundongos , Neurônios Motores/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Estresse Oxidativo/efeitos dos fármacosRESUMO
The roles of persistent Na(+) currents (INaP) in intrinsic membrane properties were examined in rat substantia gelatinosa (SG) neurons of the trigeminal subnucleus caudalis using a conventional whole-cell patch clamp technique. In a voltage-clamp mode, riluzole inhibited the slow voltage ramp-induced INaP but had little effect on the peak amplitude of transient Na(+) currents in SG neurons. In a current-clamp mode, most SG neurons exhibited spontaneous action potentials and tonic firing pattern. Riluzole reduced both spontaneous and elicited action potentials in a concentration-dependent manner. The present results suggest that the riluzole-sensitive INaP plays an important role in the excitability of SG neurons and are thus, likely to contribute to the modulation of nociceptive transmission from the orofacial tissues.
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Potenciais de Ação , Neurônios/fisiologia , Substância Gelatinosa/fisiologia , Canais de Sódio Disparados por Voltagem/fisiologia , Animais , Neurônios/efeitos dos fármacos , Técnicas de Patch-Clamp , Ratos Sprague-Dawley , Riluzol/farmacologiaRESUMO
Acid-sensing ion channels (ASICs) are widely expressed in both the peripheral and central nervous system, and contribute to the modulation of central nociceptive transmission under both physiological and pathophysiological conditions. In this study, we characterized the proton-induced membrane currents in acutely isolated rat substantia gelatinosa (SG) neurons of the trigeminal subnucleus caudalis using the whole cell patch-clamp technique. Exposure to acidic conditions (pH<6.5) induced the inward currents in a pH-dependent manner. Amiloride, a general ASIC antagonist, significantly blocked the proton-induced currents in a non-competitive manner. The pH 6.0-induced membrane current (IpH6.0) was greatly attenuated in the Na(+)-free external solution, and the reversal potential of the proton-induced currents was similar to the theoretical Na(+) equilibrium potential. The IpH6.0 was reciprocally potentiated by a lower extracellular Ca(2+) concentration. The modulation of IpH6.0 by divalent cations and other modulators suggests that the proton-induced currents are mediated by multiple types of ASIC subunits, including ASIC1a and ASIC2a. Multi-cell RT-PCR analysis revealed that SG neurons express these subunits. Exposure to a pH 6.0 solution directly depolarized the membrane potential, and generated a burst of action potentials in a current-clamp mode. This acidic pH-induced depolarization was significantly blocked by amiloride. The present results suggest that ASICs expressed on SG neurons play important roles in the regulation of nociceptive transmission from the orofacial tissues.
Assuntos
Fenômenos Eletrofisiológicos/efeitos dos fármacos , Prótons , Substância Gelatinosa/citologia , Substância Gelatinosa/efeitos dos fármacos , Animais , Anti-Inflamatórios não Esteroides/farmacologia , Ácido Araquidônico/farmacologia , Cátions Bivalentes/farmacologia , Relação Dose-Resposta a Droga , Feminino , Ácido Láctico/farmacologia , Masculino , Potenciais da Membrana/efeitos dos fármacos , Ratos , Ratos Sprague-DawleyRESUMO
The presence of antibiotics in the natural environment has been a growing issue. This presence could also account for the influence that affects microorganisms in such a way that they develop resistance against these antibiotics. The aim of this study was to evaluate whether the antibiotic resistant gene (ARG) plasmid transfer can be facilitated by the impact of 1) environmentally representative micro-contaminant concentrations in ppb (part per billion) levels and 2) donor-recipient microbial complexity (pure vs. mixed). For this purpose, the multidrug resistant plasmid, pB10, and Escherichia coli DH5α were used as a model plasmid and a model donor, respectively. Based on conjugation experiments with pure (Pseudomonas aeruginosa PAKexoT) and mixed (activated sludge) cultures as recipients, increased relative plasmid transfer frequencies were observed at ppb (µg/L) levels of tetracycline and sulfamethoxazole micro-contaminant exposure. When sludge, a more complex community, was used as a recipient, the increases of the plasmid transfer rate were always statistically significant but not always in P. aeruginosa. The low concentration (10 ppb) of tetracycline exposure led to the pB10 transfer to enteric bacteria, which are clinically important pathogens.
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Antibacterianos/análise , Farmacorresistência Bacteriana/genética , Transferência Genética Horizontal/genética , Plasmídeos/genética , Esgotos/microbiologia , Análise de Variância , Escherichia coli , Pseudomonas aeruginosa , Sulfametoxazol , TetraciclinaRESUMO
This study was conducted to assess the feasibility of image guided radiotherapy (IGRT) for orthotopic 4T1 mouse mammary tumor using linear accelerator (LINAC). Eighteen Balb/C mice were inoculated with 4T1 cells on left mammary fat pad and nine of them were irradiated using LINAC. Tumors, planning target volumes (PTV), bowels adjacent to tumors, bones and lungs were delineated on planning CT images. IGRT plans were generated to irradiate prescription dose to at least 90% of the PTV and then compared with conventional 2-dimensional plans with anterior-posterior and posterior-anterior beams with 5 mm margins (2D AP/PA plan). Homemade dose-build-up-cradle was designed to encompass mouse bed for homogeneous dose build up. To confirm the irradiated dose, tumor doses were measured using diode detector placed on the surface of tumors. Plan comparison demonstrated equivalent doses to PTV while sparing more doses to normal tissues including bowel (from 90.9% to 40.5%, median value of mean doses) and bone marrow (from 12.9% to 4.7%, median value of mean doses) than 2D AP/PA plan. Quality assurance using diode detector confirmed that IGRT could deliver 95.3-105.3% of the planned doses to PTV. Tumors grew 505.2-1185.8% (mean 873.3%) in the control group and 436.1-771.8% (mean 615.5%) in the irradiated group. These results demonstrate that LINAC-based IGRT provides a reliable approach with accurate dose delivery in the radiobiological study for orthotropic tumor model maintaining tumor microenvironment.
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We develop a new principal components analysis (PCA) type dimension reduction method for binary data. Different from the standard PCA which is defined on the observed data, the proposed PCA is defined on the logit transform of the success probabilities of the binary observations. Sparsity is introduced to the principal component (PC) loading vectors for enhanced interpretability and more stable extraction of the principal components. Our sparse PCA is formulated as solving an optimization problem with a criterion function motivated from penalized Bernoulli likelihood. A Majorization-Minimization algorithm is developed to efficiently solve the optimization problem. The effectiveness of the proposed sparse logistic PCA method is illustrated by application to a single nucleotide polymorphism data set and a simulation study.