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1.
Ecotoxicol Environ Saf ; 280: 116538, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-38833980

RESUMO

Methamphetamine (Meth) is a potent psychostimulant with well-established hepatotoxicity. Gut microbiota-derived short-chain fatty acids (SCFAs) have been reported to yield beneficial effects on the liver. In this study, we aim to further reveal the mechanisms of Meth-induced hepatic injuries and investigate the potential protective effects of SCFAs. Herein, mice were intraperitoneally injected with 15 mg/kg Meth to induce hepatic injuries. The composition of fecal microbiota and SCFAs was profiled using 16 S rRNA sequencing and Gas Chromatography/Mass Spectrometry (GC/MS) analysis, respectively. Subsequently, SCFAs supplementation was performed to evaluate the protective effects against hepatic injuries. Additionally, Sigma-1 receptor knockout (S1R-/-) mice and fluvoxamine (Flu), an agonist of S1R, were introduced to investigate the mechanisms underlying the protective effects of SCFAs. Our results showed that Meth activated S1R and induced hepatic autophagy, inflammation, and oxidative stress by stimulating the MAPK/ERK pathway. Meanwhile, Meth disrupted SCFAs product-related microbiota, leading to a reduction in fecal SCFAs (especially Acetic acid and Propanoic acid). Accompanied by the optimization of gut microbiota, SCFAs supplementation normalized S1R expression and ameliorated Meth-induced hepatic injuries by repressing the MAPK/ERK pathway. Effectively, S1R knockout repressed Meth-induced activation of the MAPK/ERK pathway and further ameliorated hepatic injuries. Finally, the overexpression of S1R stimulated the MAPK/ERK pathway and yielded comparable adverse phenotypes to Meth administration. These findings suggest that Meth-induced hepatic injuries relied on the activation of S1R, which could be alleviated by SCFAs supplementation. Our study confirms the crucial role of S1R in Meth-induced hepatic injuries for the first time and provides a potential preemptive therapy.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas , Ácidos Graxos Voláteis , Microbioma Gastrointestinal , Metanfetamina , Camundongos Knockout , Receptores sigma , Receptor Sigma-1 , Metanfetamina/toxicidade , Animais , Receptores sigma/metabolismo , Ácidos Graxos Voláteis/metabolismo , Camundongos , Microbioma Gastrointestinal/efeitos dos fármacos , Masculino , Doença Hepática Induzida por Substâncias e Drogas/prevenção & controle , Fígado/efeitos dos fármacos , Fígado/metabolismo , Camundongos Endogâmicos C57BL , Estresse Oxidativo/efeitos dos fármacos , Fezes/química , Fezes/microbiologia
2.
Sci Total Environ ; 935: 173285, 2024 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-38772488

RESUMO

Dietary pollution of Aflatoxin B1 (AFB1) poses a great threat to global food safety, which can result in serious hepatic injuries. Following the widespread use of plastic tableware, co-exposure to microplastics and AFB1 has dramatically increased. However, whether microplastics could exert synergistic effects with AFB1 and amplify its hepatotoxicity, and the underlying mechanisms are still unelucidated. Here, mice were orally exposed to 100 nm polystyrene nanoplastics (NPs) and AFB1 to investigate the influences of NPs on AFB1-induced hepatic injuries. We found that exposure to only NPs or AFB1 resulted in colonic inflammation and the impairment of the intestinal barrier, which was exacerbated by combined exposure to NPs and AFB1. Meanwhile, co-exposure to NPs exacerbated AFB1-induced dysbiosis of gut microbiota and remodeling of the fecal metabolome. Moreover, NPs and AFB1 co-exposure exhibited higher levels of systemic inflammatory factors compared to AFB1 exposure. Additionally, NPs co-exposure further exacerbated AFB1-induced hepatic fibrosis and inflammation, which could be associated with the overactivation of the TLR4/MyD88/NF-κB pathway. Notably, Spearman's correlation analysis revealed that the exacerbation of NPs co-exposure was closely associated with microbial dysbiosis. Furthermore, microbiota from NPs-exposed mice (NPsFMT) partly reproduced the exacerbation of NPs on AFB1-induced systemic and hepatic inflammation, but not fibrosis. In summary, our findings indicate that gut microbiota could be involved in the exacerbation of NPs on AFB1-induced hepatic injuries, highlighting the health risks of NPs.


Assuntos
Aflatoxina B1 , Microbioma Gastrointestinal , Fígado , Microplásticos , Poliestirenos , Aflatoxina B1/toxicidade , Animais , Camundongos , Microbioma Gastrointestinal/efeitos dos fármacos , Poliestirenos/toxicidade , Microplásticos/toxicidade , Fígado/efeitos dos fármacos , Doença Hepática Induzida por Substâncias e Drogas , Disbiose/induzido quimicamente , Nanopartículas/toxicidade
3.
Nat Prod Res ; : 1-7, 2023 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-37154381

RESUMO

Five isocoumarin derivatives including three new compounds, aspermarolides A-C (1-3), and two known analogues, 8-methoxyldiaporthin (4) and diaporthin (5) were obtained from the culture extract of Aspergillus flavus CPCC 400810. The structures of these compounds were elucidated by spectroscopic methods. The double bond geometry of 1 and 2 were assigned by the coupling constants. The absolute configuration of 3 was determined by electronic circular dichroism experiment. All compounds showed no cytotoxic activities against the two human cancer cells HepG2 and Hela.

4.
Methods Mol Biol ; 2557: 765-784, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36512250

RESUMO

The architecture of the Golgi apparatus in mammalian cells changes dynamically in response to internal and external cues and may be permanently altered in disease states. Here, we present a method to quantify changes in Golgi morphology using immunofluorescence and confocal microscopy followed by CellProfiler software analysis. This method will assist researchers in evaluating alterations in the Golgi complex morphology of cultured cells under a variety of different experimental conditions.


Assuntos
Autoantígenos , Proteínas de Membrana , Animais , Complexo de Golgi , Imunofluorescência , Software , Mamíferos
5.
J Asian Nat Prod Res ; 25(8): 796-802, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36272140

RESUMO

In this paper, we present the discovery of a novel salicylic acid derivative, moldavica acid A (1), and a new natural dibenzo[b,f]oxepin, moldavica acid B (2), together with four known phenylpropionic acids (3-6) and protocatechuic acid (7) that were isolated from Dracocephalum moldavica L. Their structures were elucidated by comprehensive spectroscopic methods, including infrared and nuclear magnetic resonance. Compound 1 is the first example of salicylic acid linking a carboxylated α-pyrone via an ethyl bridge. Beyond expanding the knowledge of the chemical diversity of D. moldavica, both compounds 1 and 2 were shown to upregulate the expression of Kruppel-like factor 2, which could serve as a prospective therapeutic target for the treatment of atherosclerosis.

6.
Artigo em Inglês | MEDLINE | ID: mdl-35911138

RESUMO

Purpose: Real-world evidence refers to patient data derived from the healthcare process. In this study, we used National Health Insurance Research Database (NHIRD) assessments and clinical studies of Ge Gen Tang (GGT, ) in patients with common cold to establish a real-world study model of Traditional Chinese Medicine formulae. GGT is widely prescribed for the treatment of common cold in Taiwan, generally in combination with other medicines. The aim of this study was to determine whether a correlation exists between GGT combined with other medicines and an improvement in cold symptoms. We also established a GGT prescription compatibility system by analyzing Taiwan's NHIRD records for GGT prescription patterns in patients with different types of common cold. Materials and Methods: We extracted and analyzed records from the NHIRD for the period 2000-2015 to determine the most common clinical applications of GGT. GGT and GGT with Chuan Xiung Cha Tiao San were most commonly prescribed for common cold, as per NHIRD recommendations. Records for adults aged 20-65 years who were prescribed GGT for the treatment of common cold (Diagnosis Code ICD-9-460) were included in this study. We assessed the following indicators of the common cold, before and after treatment with GGT: nasal congestion, cough, runny nose, sneezing, sore throat, hoarseness, stiff shoulder, headache, and general physical condition. Results: The cold symptom scores before and after taking the GGT prescriptions significantly differed in the 29 volunteers. The 29 volunteers reported a significantly lower headache severity score after medication than before medication (p < 0.004). Furthermore, patient scores for general physical condition decreased significantly (p < 0.01) after medication.

7.
ACS Appl Mater Interfaces ; 13(14): 16418-16426, 2021 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-33818075

RESUMO

In this study, nanocrystals of a cerium-based metal-organic framework (Ce-MOF), Ce-MOF-808, are directly grown on the surface of carboxylic acid-functionalized carbon nanotubes (CNTs) by a facile one-step solvothermal synthesis method. Ce-MOF-CNT nanocomposites with various Ce-MOF-to-CNT ratios are synthesized, and their crystallinity, morphology, porosity, and electrical conductivity are examined. The redox-hopping and electrochemical behaviors of the pristine Ce-MOF in aqueous electrolytes are investigated, suggesting that the pristine Ce-MOF is electrochemically active but possesses a limited charge-transport behavior. As a demonstration, all the Ce-MOF, CNT, and nanocomposites are used as active materials for application in aqueous-based supercapacitors. The capacitive performance of the CNT can be significantly boosted with the help of redox-active Ce-MOF-808 nanocrystals.

8.
Nat Commun ; 12(1): 888, 2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33563962

RESUMO

The design principle of establishing an intracellular protein gradient for asymmetric cell division is a long-standing fundamental question. While the major molecular players and their interactions have been elucidated via genetic approaches, the diversity and redundancy of natural systems complicate the extraction of critical underlying features. Here, we take a synthetic cell biology approach to construct intracellular asymmetry and asymmetric division in Escherichia coli, in which division is normally symmetric. We demonstrate that the oligomeric PopZ from Caulobacter crescentus can serve as a robust polarized scaffold to functionalize RNA polymerase. Furthermore, by using another oligomeric pole-targeting DivIVA from Bacillus subtilis, the newly synthesized protein can be constrained to further establish intracellular asymmetry, leading to asymmetric division and differentiation. Our findings suggest that the coupled oligomerization and restriction in diffusion may be a strategy for generating a spatial gradient for asymmetric cell division.


Assuntos
Divisão Celular Assimétrica , Escherichia coli/citologia , Escherichia coli/metabolismo , Espaço Intracelular/metabolismo , Bacillus subtilis/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Caulobacter crescentus/genética , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Diferenciação Celular , Polaridade Celular , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica
9.
Chemistry ; 27(10): 3560-3567, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33166095

RESUMO

In this study, a strategy that can result in the polyaniline (PANI) solely confined within the nanopores of a metal-organic framework (MOF) without forming obvious bulk PANI between MOF crystals is developed. A water-stable zirconium-based MOF, UiO-66-NH2 , is selected as the MOF material. The polymerization of aniline is initiated in the acidic suspension of UiO-66-NH2 nanocrystals in the presence of excess poly(sodium 4-styrenesulfonate) (PSS). Since the pore size of UiO-66-NH2 is too small to enable the insertion of the bulky PSS, the quick formation of pore-confined solid PANI and the slower formation of well dispersed PANI:PSS occur within the MOF crystals and in the bulk solution, respectively. By taking advantage of the resulting homogeneous PANI:PSS polymer solution, the bulk PANI:PSS can be removed from the PANI/UiO-66-NH2 solid by successive washing the sample with fresh acidic solutions through centrifugation. As this is the first time reporting the PANI solely confined in the pores of a MOF, as a demonstration, the obtained PANI/UiO-66-NH2 composite material is applied as the electrode material for supercapacitors. The PANI/UiO-66-NH2 thin films exhibit a pseudocapacitive electrochemical characteristic, and their resulting electrochemical activity and charge-storage capacities are remarkably higher than those of the bulk PANI thin films.

10.
Chem Commun (Camb) ; 56(79): 11763-11766, 2020 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-32930153

RESUMO

A redox-active vanadium-based polyoxometalate, V10O28, was post-synthetically immobilized into a water-stable zirconium-based metal-organic framework, NU-902. The adsorbed V10O28 in NU-902 renders charge hopping in the framework in aqueous electrolytes, and the obtained V10O28@NU-902 can be used as a heterogeneous electrocatalyst for electrochemical dopamine sensors.


Assuntos
Ânions/química , Dopamina/análise , Estruturas Metalorgânicas/química , Polieletrólitos/química , Vanadatos/química , Adsorção , Catálise , Dopamina/química , Técnicas Eletroquímicas/métodos , Limite de Detecção , Oxirredução
11.
Sci Rep ; 10(1): 11952, 2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32686708

RESUMO

N-myristoyltransferase-1 (NMT1) catalyzes protein myristoylation, a lipid modification that is elevated in cancer cells. NMT1 sustains proliferation and/or survival of cancer cells through mechanisms that are not completely understood. We used genetic and pharmacological inhibition of NMT1 to further dissect the role of this enzyme in cancer, and found an unexpected essential role for NMT1 at promoting lysosomal metabolic functions. Lysosomes mediate enzymatic degradation of vesicle cargo, and also serve as functional platforms for mTORC1 activation. We show that NMT1 is required for both lysosomal functions in cancer cells. Inhibition of NMT1 impaired lysosomal degradation leading to autophagy flux blockade, and simultaneously caused the dissociation of mTOR from the surface of lysosomes leading to decreased mTORC1 activation. The regulation of lysosomal metabolic functions by NMT1 was largely mediated through the lysosomal adaptor LAMTOR1. Accordingly, genetic targeting of LAMTOR1 recapitulated most of the lysosomal defects of targeting NMT1, including defective lysosomal degradation. Pharmacological inhibition of NMT1 reduced tumor growth, and tumors from treated animals had increased apoptosis and displayed markers of lysosomal dysfunction. Our findings suggest that compounds targeting NMT1 may have therapeutic benefit in cancer by preventing mTORC1 activation and simultaneously blocking lysosomal degradation, leading to cancer cell death.


Assuntos
Aciltransferases/metabolismo , Lisossomos/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Neoplasias/metabolismo , Animais , Autofagia , Linhagem Celular Tumoral , Endossomos/metabolismo , Ativação Enzimática , Imunofluorescência , Humanos , Camundongos , Proteólise
13.
ACS Appl Mater Interfaces ; 11(38): 35319-35326, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31423762

RESUMO

Graphene quantum dots (GQD) with an average size of 3.1 nm were incorporated into a mesoporous porphyrinic zirconium-based metal-organic framework (MOF) by direct impregnation to render the donor-acceptor charge transfer from GQDs to porphyrinic linkers. The hybrid material still possesses around half porosity of the pristine MOF and shows a 100-fold higher electrical conductivity compared to that of the parent MOF. By utilizing the porphyrinic linkers as catalytically active units, the GQD-MOF material exhibits a better electrochemical sensing activity toward nitrite in aqueous solutions compared to both the pristine MOF and GQD.

14.
MethodsX ; 6: 718-726, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31011543

RESUMO

Invadopodia, cancer cell protrusive structures with associated proteolytic activity, provide cancer cells with the ability to remodel the extracellular matrix. Invadopodia facilitate invasive migration and their formation correlates with cancer cell invasiveness and metastatic potential. The unambiguous identification of invadopodia is an important step to undergo studies on invadopodia regulatory inputs, functional outputs, as well as the prevalence and significance of invadopodia for cancer cells and human tumors. The adaptor protein TKS5 is a known invadopodia regulatory protein, which is necessary for invadopodia formation and activity. TKS5 is highly enriched at invadopodia and, unlike other commonly used invadopodia markers, it does not accumulate significantly in other types of cellular protrusions. However, the use of TKS5 as a marker of invadopodia has not been generalized, in part due to the availability of suitable antibodies against the human protein. We have evaluated two commercial antibodies raised against human TKS5. Here, we detail protocols for the detection of invadopodia-associated TKS5 in human cells in culture and in paraffin-embedded archived tumor surgical specimens using commercial antibodies. These methods should facilitate the identification and study of human invadopodia. •TKS5 staining identifies invadopodia in human cancer cell lines and archived surgical tumor specimens.

15.
Exp Mol Pathol ; 106: 17-26, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30439350

RESUMO

Invadopodia, cancer cell protrusions with proteolytic activity, are functionally associated with active remodeling of the extracellular matrix. Here, we show that the invadopodia-related protein TKS5 is expressed in human pancreatic adenocarcinoma lines, and demonstrate that pancreatic cancer cells depend on TKS5 for invadopodia formation and function. Immunofluorescence staining of human pancreatic cancer cells reveals that TKS5 is a marker of mature and immature invadopodia. We also analyze the co-staining patterns of TKS5 and the commonly used invadopodia marker Cortactin, and find only partial co-localization of these two proteins at invadopodia, with a large fraction of TKS5-positive invadopodia lacking detectable levels of Cortactin. Whereas compelling evidence exist on the role of invadopodia as mediators of invasive migration in cultured cells and in animal models of cancer, these structures have never been detected inside human tumors. Here, using antibodies against TKS5 and Cortactin, we describe for the first time structures strongly resembling invadopodia in various paraffin-embedded human tumor surgical specimens from pancreas and other organs. Our results strongly suggest that invadopodia are present inside human tumors, and warrants further investigation on their regulation and occurrence in surgical specimens, and on the value of TKS5 antibodies as pathological research and diagnostic tools.


Assuntos
Proteínas Adaptadoras de Transporte Vesicular/fisiologia , Adenocarcinoma/patologia , Proteínas de Neoplasias/fisiologia , Neoplasias Pancreáticas/patologia , Podossomos/fisiologia , Adenocarcinoma/química , Adenocarcinoma/cirurgia , Adenocarcinoma/ultraestrutura , Adulto , Idoso , Linhagem Celular Tumoral , Cortactina/análise , Feminino , Técnica Direta de Fluorescência para Anticorpo , Humanos , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Neoplasias/química , Neoplasias/patologia , Neoplasias Pancreáticas/química , Neoplasias Pancreáticas/cirurgia , Neoplasias Pancreáticas/ultraestrutura , Inclusão em Parafina , Podossomos/química , Podossomos/ultraestrutura , Interferência de RNA , RNA Interferente Pequeno/genética
16.
Data Brief ; 22: 132-136, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30581916

RESUMO

In this article, using human pancreatic cancer cell lines and tumor specimens, we analyze the expression and localization of the invadopodia-related proteins TKS5 and Cortactin. Specifically, we present data on: a) TKS5 expression and localization by immunofluorescence in human pancreatic tumors, b) Cortactin expression by western blotting in various human pancreatic adenocarcinoma cell lines, c) TKS5 and Cortactin localization at invadopodia in BxPC-3 pancreatic adenocarcinoma cells, and d) TKS5 and Cortactin localization by co-immunofluorescence in human pancreatic cancer specimens. Data presented here is related to and supportive of the research article by Chen et al., "TKS5-positive invadopodia-like structures in human tumor surgical specimens" (Chen et al., 2019), where interpretation of the research data presented here is available.

17.
Reprod Toxicol ; 82: 111-123, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30316929

RESUMO

2-hydroxy-4-methoxybenzophenone (HMB) is an ultraviolet light-absorbing compound that is used in sunscreens, cosmetics and plastics. HMB has been reported to have weak estrogenic activity by in vivo and in vitro studies, making it a chemical with potential reproductive concern. To explore if prenatal and lactational HMB exposure alters gene expression profiles of the developing reproductive organs, we performed microarray analysis using the prostate and testis of postnatal day (PND) 30 male Sprague-Dawley rats offspring exposed to 0, 3000, or 30,000 ppm of HMB from gestational day 6 through PND 21. Gene expression profiles of the prostate and testis were differentially affected by HMB dose with significant alterations observed at the 30,000 ppm HMB group. Tissue-specific gene expression was also identified. These genes, whose expression was altered by HMB exposure, may be considered as candidate biomarker(s) for testicular or prostatic toxicity; however, further studies are necessary to explore this potential.


Assuntos
Benzofenonas/toxicidade , Cosméticos/toxicidade , Próstata/efeitos dos fármacos , Testículo/efeitos dos fármacos , Animais , Feminino , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Lactação , Masculino , Troca Materno-Fetal , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Próstata/metabolismo , Ratos Sprague-Dawley , Testículo/metabolismo
18.
Biomark Med ; 12(8): 849-859, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-30022678

RESUMO

AIM: We develop a subgroup selection procedure using both prognostic and predictive biomarkers to identify four patient subpopulations: low- and high-risk responders, and low- and high-risk nonresponders. METHODS: We utilize three regression models to identify three sets of biomarkers: S, prognostic biomarkers; T, predictive biomarkers; and U, prognostic and predictive biomarkers. The prognostic signature C(S) combines with a predictive signature, either C(T) or C(U), to develop two procedures C(S,T) and C(S,U) for identification of four subgroups. RESULTS: Simulation experiment showed that proposed models for identifying the biomarker sets S and U performed well, as did the procedure C(S,U) for subgroup identification. CONCLUSION: The proposed model provides more comprehensive characterization of patient subpopulations, and better accuracy in patient treatment assignment.


Assuntos
Tomada de Decisão Clínica , Simulação por Computador , Modelos Teóricos , Biomarcadores/metabolismo , Humanos
19.
Pharm Stat ; 17(2): 105-116, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29297979

RESUMO

For survival endpoints in subgroup selection, a score conversion model is often used to convert the set of biomarkers for each patient into a univariate score and using the median of the univariate scores to divide the patients into biomarker-positive and biomarker-negative subgroups. However, this may lead to bias in patient subgroup identification regarding the 2 issues: (1) treatment is equally effective for all patients and/or there is no subgroup difference; (2) the median value of the univariate scores as a cutoff may be inappropriate if the sizes of the 2 subgroups are differ substantially. We utilize a univariate composite score method to convert the set of patient's candidate biomarkers to a univariate response score. We propose applying the likelihood ratio test (LRT) to assess homogeneity of the sampled patients to address the first issue. In the context of identification of the subgroup of responders in adaptive design to demonstrate improvement of treatment efficacy (adaptive power), we suggest that subgroup selection is carried out if the LRT is significant. For the second issue, we utilize a likelihood-based change-point algorithm to find an optimal cutoff. Our simulation study shows that type I error generally is controlled, while the overall adaptive power to detect treatment effects sacrifices approximately 4.5% for the simulation designs considered by performing the LRT; furthermore, the change-point algorithm outperforms the median cutoff considerably when the subgroup sizes differ substantially.


Assuntos
Seleção de Pacientes , Medicina de Precisão/mortalidade , Medicina de Precisão/métodos , Bases de Dados Factuais/tendências , Humanos , Funções Verossimilhança , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/mortalidade , Neoplasias Pulmonares/terapia , Medicina de Precisão/tendências , Taxa de Sobrevida/tendências , Resultado do Tratamento
20.
Biom J ; 58(5): 1151-63, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27073016

RESUMO

Recently, personalized medicine has received great attention to improve safety and effectiveness in drug development. Personalized medicine aims to provide medical treatment that is tailored to the patient's characteristics such as genomic biomarkers, disease history, etc., so that the benefit of treatment can be optimized. Subpopulations identification is to divide patients into several different subgroups where each subgroup corresponds to an optimal treatment. For two subgroups, traditionally the multivariate Cox proportional hazards model is fitted and used to calculate the risk score when outcome is survival time endpoint. Median is commonly chosen as the cutoff value to separate patients. However, using median as the cutoff value is quite subjective and sometimes may be inappropriate in situations where data are imbalanced. Here, we propose a novel tree-based method that adopts the algorithm of relative risk trees to identify subgroup patients. After growing a relative risk tree, we apply k-means clustering to group the terminal nodes based on the averaged covariates. We adopt an ensemble Bagging method to improve the performance of a single tree since it is well known that the performance of a single tree is quite unstable. A simulation study is conducted to compare the performance between our proposed method and the multivariate Cox model. The applications of our proposed method to two public cancer data sets are also conducted for illustration.


Assuntos
Algoritmos , Modelos Biológicos , Medicina de Precisão/métodos , Simulação por Computador , Humanos , Neoplasias/terapia , Risco
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