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OBJECTIVE: To find new biomarkers for early diagnosis of breast cancer. RESULTS: 847 lipid species were identified from 78 plasma samples (37 breast cancer samples and 41 healthy controls) by ultra HPLC coupled with quadrupole time-of-flight tandem mass spectrometry. These include 321 glycerophospholipids (GPs), 265 glycerolipids (GLs), 91 sphingolipids (SPs), 77 fatty acyls (FAs), 68 sterol lipids (STs), 18 prenol lipids (PRs), 6 polyketides (PKs), and 1 saccharolipid (SL). Separation was observed from an orthogonal signal correction Partial Least Square Discrimination Analysis model. Based on this analysis, six differentiating lipids were identified: PC (20:2/20:5), PC (22:0/24:1), TG (12:0/14:1), and DG (18:1/18:2) had high levels, whereas PE (15:0/19:1) and N-palmitoyl proline had low levels in the breast cancer samples compared with the healthy controls. Furthermore, significant differences in metabolites were found among some clinical characteristics. CONCLUSIONS: Our results reveal that six specific lipids could serve as potential biomarkers for early diagnosis of breast cancer.
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Biomarcadores Tumorais/sangue , Neoplasias da Mama/patologia , Lipídeos/sangue , Adulto , Idoso , Biomarcadores Tumorais/análise , Neoplasias da Mama/sangue , Neoplasias da Mama/metabolismo , Estudos de Casos e Controles , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Análise dos Mínimos Quadrados , Lipídeos/análise , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Espectrometria de Massas em TandemRESUMO
Many experimental factors and uncontrollable factors may introduce errors in the distance measurement by continuous wave electron paramagnetic resonance. To deal with this problem, several C60 nitroxide diradical adducts with rigid structure and definite molecular dimension were used as distance calibration rulers. Based on the improvement of distance calculation program via adding simulation programs of experimental spectra and dipolar broadening function, respectively, the distance calibration method was developed under different conditions such as different solvent, solution concentration, measuring temperature, and microwave power. As a result, stable distance calibration rulers were established within the range of 8-13 Å. The distance calibration effect was evaluated resulting in a corresponding distance measurement precision of 0.84 Å. The results suggested that the influence of non-dipolar spectral broadening factors could be overcome, and the established experimental and calculation methods were suitable to a wide range of situations. The developed method will ensure more accurate and objective distance measurement in biomacromolecular analysis.
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Espectroscopia de Ressonância de Spin Eletrônica/métodos , Calibragem , Estrutura MolecularRESUMO
OBJECTIVE: To assess the diagnostic performance of clinically common single markers and combinations to distinguish nonmetastatic breast cancer and benign breast tumor. A predictive model with a better diagnostic ability for nonmetastatic breast cancer was established by using the diagnostic process. METHODS: A total of 222 patients with nonmetastatic breast cancer and 265 patients with benign breast disease were enrolled in this study. CEA, Ca 15-3, Ca 125, Ca 72-4, CYFRA 21-1, FERR, AFP, and NSE were measured by an electrochemiluminescent immunoenzymometric assay on the Elecsys system. There are four key steps for our diagnostic workflow, that is, feature selection, algorithm selection, parameter optimization, and outer test data was used to validate the optimal algorithm and markers. RESULTS: CEA, Ca 15-3, CYFRA 21-1, AFP, and FERR were selected using the t-test in our inner development set. The optimal algorithm among logical regression, decision tree, support vector machine, random forest, and gradient boost machine was selected by 10-fold cross-validation, and we found that random forest and logistic regression are the better classification. The outer test data was used to validate the best markers and classification. The random forest with CEA, Ca 15-3, CYFRA 21-1, AFP, and FERR showed the optimal combination for distinguishing breast cancer and benign breast disease. The AUC value was 0.888, the cut-off point was 0.484, and sensitivity and specificity were 78.9% and 90.1%. CONCLUSIONS: No single marker of these eight markers was good at identifying nonmetastatic breast cancer from benign tumors. But a diagnostic analysis workflow was established to develop a predictive model with better diagnostic capability for nonmetastatic breast cancer. This workflow is also applicable to the optimization of other disease markers and diagnostic models. The predictive model showed good diagnostic performance, and it could be gradually incorporated as a support method for the diagnosis of nonmetastatic breast cancer.
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The objective of this study was to identify potential biomarkers and possible metabolic pathways of malignant and benign thyroid nodules through lipidomics study. A total of 47 papillary thyroid carcinomas (PTC) and 33 control check (CK) were enrolled. Plasma samples were collected for UPLC-Q-TOF MS system detection, and then OPLS-DA model was used to identify differential metabolites. Based on classical statistical methods and machine learning, potential biomarkers were characterized and related metabolic pathways were identified. According to the metabolic spectrum, 13 metabolites were identified between PTC group and CK group, and a total of five metabolites were obtained after further screening. Its metabolic pathways were involved in glycerophospholipid metabolism, linoleic acid metabolism, alpha-linolenic acid metabolism, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, Phosphatidylinositol signaling system and the metabolism of arachidonic acid metabolism. The metabolomics method based on PROTON nuclear magnetic resonance (NMR) had great potential for distinguishing normal subjects from PTC. GlcCer(d14:1/24:1), PE-NME (18:1/18:1), SM(d16:1/24:1), SM(d18:1/15:0), and SM(d18:1/16:1) can be used as potential serum markers for the diagnosis of PTC.
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Although intestinal tuberculosis (ITB) typically affects ileocecal segments, the complication of tubercular enterocutaneous fistula is very rare. As an isolated phenomenon, primary intestinal manifestation without extraintestinal tuberculosis (TB) is exceptional and rarely reported. We present a patient with isolated ITB with six spontaneous thoracolumbar tubercular enterocutaneous fistulae. A 37-year-old Chinese woman was admitted to our institution complaining of escape of fecal matter through several openings in her back over the previous 20 years. She had nonspecific abdominal symptoms (occasional abdominal pain and alteration in bowel habit). External physical examination confirmed the presence of external thoracolumbar fecal fistulae in association with a scoliosis. Abdominal examination was unremarkable. Diagnostic colonoscopy with biopsy did not definitively confirm a diagnosis of TB. Microscopic examination in both microbiology and histopathology labs failed to identify acid-fast bacilli; however, gastrointestinal TB (GITB) was considered high on the differential diagnosis list. It was elected to perform open laparotomy with resection of the left hemi-colon. Postoperatively, she was treated with standard anti-tuberculous treatment for 6 months. The patient had an uneventful postoperative course, during which the fistulae gradually closed over the next year. This case with several low-output fistulas exiting the patient's back was successfully treated by a combination of surgery and antimicrobial therapy. The aim of this rare case report is to raise the awareness of atypical presentation of tubercular colonic enterocutaneous fistula so that timely diagnosis and intervention can salvage patient quality of life.
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OBJECTIVE: To investigate the expression of aquaporin 4 (AQP4) after microwave exposure and the correlation with the brain injury by radiation. METHODS: 70 male rats were exposed to microwave whose average power density was 0, 10, 30 and 100 mW/cm(2) respectively. Rats were sacrificed at 6 h, 1 d, 3 d and 7 d after exposure. Immunohistochemistry and Western blot were used to detect the expression of AQP4 in protein level in rat hippocampus, and the expression of AQP4 in gene level was measured by in situ hybridization and RT-PCR. RESULTS: The expression of AQP4 in rat hippocampus was abnormal after 10, 30, 100 mW/cm(2) microwave exposure. The protein level showed increased at first and then recovered at 10 and 30 mW/cm(2) groups, while increased progressively in 100 mW/cm(2) group within 14 d (P < 0.01). The gene expression of AQP4 was increased (0.51 +/- 0.02) at the beginning (6 h) and then regained after 10 mW/cm(2) microwave exposure, while in 30 and 100 mW/cm(2) groups, it rose to the peak at 7 d (0.46 +/- 0.02 and 0.43 +/- 0.08) and didn't get back (P = 0.004; P = 0.012). CONCLUSION: Microwave radiation can increase the expression of AQP4 in rat hippocampus. The change might participate in the process of increasing permeability of blood-brain barrier and lead to the brain edema after microwave radiation.
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Aquaporina 4/metabolismo , Hipocampo/metabolismo , Micro-Ondas/efeitos adversos , Animais , Aquaporina 4/genética , Hipocampo/efeitos da radiação , Masculino , Ratos , Ratos WistarRESUMO
The development of new dosimeters with good dosimetric properties is important for quality control in radiation applications. A new practical electron spin resonance (ESR) dosimeter based on carbonated hydroxyapatite that simulated the composition and structure of tooth enamel was specially synthesized. The synthesized material was investigated by transmission electron microscope, X-ray diffraction, fourier transform infrared spectroscopy and X-ray photo electron spectroscopy to confirm to the main composition of carbonated hydroxyapatite with CO32- successfully doped into the crystal lattice through optimizing the synthesis process of C/P molar ratio, pH value dynamical adjustment, annealing temperature and time. The dosimetric properties were systematically investigated by ESR spectroscopy. The results indicated that the radiation induced signal had a good dose response within a relatively wide dose range. The dose response was linear in the dose range of 0-400 Gy with a correlation coefficient of 0.9999 and had dose accumulative effect in the experimental dose range of 0-100 Gy. In a wider dose range up to 30 kGy, the dose response also presented linear feature in double-logarithmic coordinate system with a correlation coefficient of 0.9970. The dose detection limit was about 0.34Gy with a given probability of 95% confidence level depending upon a rigid calculation algorithm. The signal was extremely stable in the observation time of 360 days with a variation coefficient of 3.8%. The radiation sensitivity of the material showed no remarkable variation against photon energy from 662 KeV to 1.25 MeV and dose rate from 0.86 Gy/min to 12.17 Gy/min. The material showed more sensitive in lower photon energy range below 662 keV, which hint additional calibration may need when using in special photon energy condition. The preliminary results suggested that this newly developed dosimeter was potential to become a practical dosimeter that would expand the application fields of ESR dosimetry.
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Carbonatos/química , Durapatita/química , Espectroscopia de Ressonância de Spin Eletrônica , Dosímetros de Radiação , Limite de Detecção , FótonsRESUMO
Numerous studies have shown that acute microwave exposure causes cognitive deficits in animals, possibly via hyperthermia, but the biological effect of microwave exposure on memory processing is still unknown. The release of adenosine is demonstrated to be a general way for the cells to respond to metabolically stressful conditions such as hypoxia and ischemia. The present study aimed to examine whether adenosine mediates biological effects of microwave exposure on memory processing using a continuous multiple-trial inhibitory avoidance task. Results demonstrated that microwave exposure for 20 min before training impaired memory acquisition and retention performance in mice, assessed by the number of training trials and by latency to enter the dark compartment. The mice exposed to microwave radiation showed a dose-dependent hyperthermia. Moreover, the cell numbers of hippocampus were decreased in the mice receiving microwave exposure at an average power density of 50 mW/cm(2), indicating the anatomical correlation to hippocampal-amygdaloid structures corresponding with the memory disrupt of the mice. Administration of theophylline, a nonspecific adenosine receptor antagonist, 30 min before microwave exposure, completely antagonized the impairment of inhibitory avoidance acquisition but not retention. These results suggest that the adenosine regulation pathway was partially involved in microwave-induced impairment of inhibitory avoidance memory.
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Adenosina/metabolismo , Hipocampo/efeitos da radiação , Transtornos da Memória/etiologia , Micro-Ondas/efeitos adversos , Antagonistas de Receptores Purinérgicos P1 , Teofilina/uso terapêutico , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Aprendizagem da Esquiva/efeitos da radiação , Temperatura Corporal/efeitos da radiação , Febre/etiologia , Febre/metabolismo , Febre/fisiopatologia , Hipocampo/efeitos dos fármacos , Hipocampo/fisiopatologia , Masculino , Memória/efeitos dos fármacos , Memória/efeitos da radiação , Transtornos da Memória/tratamento farmacológico , Transtornos da Memória/fisiopatologia , Camundongos , Inibidores de Fosfodiesterase/uso terapêutico , Doses de Radiação , Receptores Purinérgicos P1/metabolismo , Resultado do TratamentoRESUMO
Second mitochondria-derived activator of caspases (SMAC) mimetics is a class of new anticancer agents. However, most cancers exhibit de novo or acquired resistance to SMAC mimetics, posting a problem for broad applications in clinic, and highlighting the necessity of exploring combinational strategies to circumvent SMAC mimetic-resistance. We here showed that Norcantharidin, a drug that is currently being used in cancer treatment, significantly enhanced SMAC mimetic Birinapant-mediated cell viability inhibition and robustly promoted apoptosis in established breast carcinoma cell lines, as well as in primary breast carcinoma cells. Mechanistically, we revealed that Norcantharidin effectively reduced the levels of two major protein isoforms of cellular FLICE-like inhibitor protein(c-FLIP), namely c-FLIP long (c-FLIPL) and c-FLIP short (c-FLIPS). Moreover, Norcantharidin markedly enhanced Birinapant-triggered caspase-8/caspase-3 cascade. Inhibition of caspase-8 activity by a synthetic peptide Z-IETD-FMK significantly attenuated cell death induction by the combination, suggesting that caspase-8 plays a critical role in the anticancer action. In conclusion, our study suggests that the combination of SMAC mimetics with Norcantharidin represents a novel strategy in breast cancer therapy and warrants further studies.
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Antineoplásicos/farmacologia , Neoplasias da Mama/genética , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/genética , Dipeptídeos/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Indóis/farmacologia , Apoptose/efeitos dos fármacos , Caspase 8/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Feminino , HumanosRESUMO
PURPOSE: Intracellular electroporation occurs when the cells are exposed to nanosecond pulsed electric field (nsPEF). It is believed the electroporation (formation and extension of pores on the membrane induced by external electric field) is affected significantly by the transmembrane potential. This paper analyzed transmembrane potential induced by nsPEF in the term of pulse frequency spectrum, aiming to provide a theoretical explanation to intracellular bio-effects. METHODS: Based on the double-shelled spherical cell model, the frequency dependence of transmembrane potential was obtained by solving Laplace's equation, while the time course of transmembrane potential was obtained by a method combined with discrete Fourier transform and Laplace transform. First-order Debye equation was used to describe the dielectric relaxation of the cell medium. RESULTS: Frequency-domain analysis showed that when the electric field frequency was higher than 105 Hz, the transmembrane potential on the organelle membrane (ΔΦo) was increasing to exceed the transmembrane potential on the cellular membrane (ΔΦc). In the time-domain analysis, transmembrane potentials induced by four nsPEF (short trapezoid, long trapezoid, bipolar and sine shapes) with the same field strength were compared with each other. It showed that ΔΦo is obviously larger than ΔΦc if the curve of the normalized frequency spectrum of the pulse is more similar with the curve of normalized ΔΦo in frequency domain. Pulses with major frequency components higher than 108 Hz lead to both small ΔΦo and ΔΦc. This may explain why high power pulsed microwave lead to unobvious bio-effects of cells than nsPEF with trapezoid form. CONCLUSION: Through the pulse frequency spectrum it is clearer to understand the relationship between nsPEF and the transmembrane potential.
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Membrana Celular/efeitos da radiação , Campos Eletromagnéticos , Eletroporação/métodos , Potenciais da Membrana/fisiologia , Potenciais da Membrana/efeitos da radiação , Modelos Biológicos , Animais , Membrana Celular/fisiologia , Simulação por Computador , Relação Dose-Resposta à Radiação , Humanos , Doses de RadiaçãoRESUMO
Nasal swab analysis is an effective method to provide valuable information for early and fast estimates of alpha radionuclide intakes and resultant doses. In this study, an inhalation environment was built by use of lead nitrate aerosol to simulate alpha radioactive aerosol inhalation. The result of exposure and swabbing experiments with guinea pigs shows that the lead smeared on nasal swabs represents â¼13 % of intake if samples are acquired within 90 min after exposure and declines over time with a half-time of 1.4 h. The results also indicate a decreasing swabbing efficiency with post-exposure time. This study could provide useful information for the method of nasal swab used in nuclear and radiological emergencies.
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Poluentes Radioativos do Ar/análise , Partículas alfa , Chumbo/análise , Cavidade Nasal/metabolismo , Nitratos/análise , Monitoramento de Radiação/métodos , Administração por Inalação , Animais , Cobaias , Chumbo/administração & dosagem , Masculino , Nitratos/administração & dosagemRESUMO
A set of fluence-to-dose conversion coefficients has been calculated for neutrons with energies <20 MeV using a developed voxel mouse model and Monte Carlo N-particle code (MCNP), for the purpose of neutron radiation effect evaluation. The calculation used 37 monodirectional monoenergetic neutron beams in the energy range 10(-9) MeV to 20 MeV, under five different source irradiation configurations: left lateral, right lateral, dorsal-ventral, ventral-dorsal, and isotropic. Neutron fluence-to-dose conversion coefficients for selected organs of the body were presented in the paper, and the effect of irradiation geometry conditions, neutron energy and the organ location on the organ dose was discussed. The results indicated that neutron dose conversion coefficients clearly show sensitivity to irradiation geometry at neutron energy below 1 MeV.
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Nêutrons , Especificidade de Órgãos/efeitos da radiação , Doses de Radiação , Absorção de Radiação , Animais , Masculino , Camundongos , Modelos AnimaisRESUMO
In vivo electron paramagnetic resonance tooth dosimetry could be a practical and ideal tool for quick mass triage of victims in the rescue following a disaster event involving irradiation radiation. Magnetic field modulation is an important issue to improve the sensitivity of X-band in vivo tooth dosimetry. We designed a couple of trapezoidal modulation coil sets fixed on the magnet poles that could be used to apply sufficient magnet field modulation into the detection aperture of the resonant cavity. Measurements of irradiated teeth with such coil sets demonstrated significant radiation-induced signals. The modulation generation efficiencies and magnetic field distributions in apertures with different cavity geometries were analytically calculated, simulated by a finite element method and evaluated by measurements of a free radical point sample to study the influences caused by the geometries of the apertures and other factors.
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Bioensaio/instrumentação , Espectroscopia de Ressonância de Spin Eletrônica/instrumentação , Magnetismo/instrumentação , Radiometria/instrumentação , Dente/química , Dente/efeitos da radiação , Transdutores , Desenho Assistido por Computador , Módulo de Elasticidade , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Campos Magnéticos , Micro-Ondas , Miniaturização , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
OBJECTIVE: To investigate the effect of high power microwave (HPM) radiation on the expression of beta(1)-adrenergic receptor (beta(1)-AR) and M(2)-muscarinic acetylcholine receptor (M(2)-AchR) in cardiomyocytes. METHODS: S-band HPM device of mean power density 2 approximately 90 mW/cm(2) was used to irradiate 150 healthy Wistar male rats. Immunohistochemistry and image analysis were used to study the pathological characteristics of heart tissue and the expression of beta(1)-AR and M(2)-AchR. RESULTS: Radiation of over 10 mW/cm(2) made myocardial fibers disordered in arrangement, degeneration even sarcoplasm condensation, Pace cells necrosis, and Purkinje cells lysis in a dose-dependent manner (r = 0.968, P < 0.05). beta(1)-AR expression in endocardium, membrane and cytoplasm of myocardium of left ventricle was increased on d1 after radiation, peaked on d3 (P < 0.05) and recovered on d14. M(2)-AchR expression was peaked on d1 (P < 0.01) and recovered on d14. CONCLUSION: Certain degree intensity of HPM radiation may cause heart injury, and increased expressions of beta(1)-AR and M(2)-AchR, which may play an important role in the pathophysiology of heart injury induced by HPM.
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Coração/efeitos da radiação , Micro-Ondas/efeitos adversos , Miócitos Cardíacos/metabolismo , Receptor Muscarínico M2/biossíntese , Receptores Adrenérgicos beta 1/biossíntese , Animais , Relação Dose-Resposta à Radiação , Masculino , Miócitos Cardíacos/efeitos da radiação , Ratos , Ratos WistarRESUMO
BACKGROUND: To investigate the expression and clinical significance of zinc finger protein 217 (ZNF217) in human colorectal carcinoma (CRC). MATERIALS AND METHODS: The expression of ZNF217 in 60 CRC tissues and matched tumor adjacent tissues, collected between January 2013 and June 2014, was assessed immunohistochemically. The relationship between the expression of ZNF217 and clinicopathlogical features was analyzed by Pearson chi-square test. In addition, siRNA was used to down-regulate the expression of ZNF217 in CRC cells. The effects of ZNF217 for cell migration and invasion were measured by wound healing assay and transwell assay, respectively. RESULTS: The expression level of ZNF217 was significantly higher in CRC tissues than in tumor adjacent tissues (p<0.05), positively correlating with tumor size, lymphatic metastasis and advanced TNM stage (p<0.05). Down-regulation of ZNF217 in CRC cells could significantly suppress cell migration and invasion. CONCLUSIONS: ZNF217 is overexpressed in colorectal carcinoma tissues and is associated with tumor malignant clinicopathological features. ZNF217 may promote CRC progression by inducing cell migration and invasion.
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Biomarcadores Tumorais/metabolismo , Movimento Celular , Proliferação de Células , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Transativadores/metabolismo , Adulto , Idoso , Apoptose , Biomarcadores Tumorais/genética , Western Blotting , Adesão Celular , Células Cultivadas , Colo/metabolismo , Neoplasias Colorretais/mortalidade , Feminino , Seguimentos , Humanos , Técnicas Imunoenzimáticas , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Invasividade Neoplásica , Estadiamento de Neoplasias , Prognóstico , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reto/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Taxa de Sobrevida , Transativadores/genéticaRESUMO
Splenic abscess is a rare clinical entity. The present study reports a case of a patient that suffered from splenic abscess secondary to septicemia resulting from Klebsiella pneumoniae infection following the removal of the feeding jejunostomy tube that was utilized subsequent to the patient undergoing total gastrectomy as part of the treatment regimen for gastric adenocarcinoma. The early clinical presentation was nonspecific and multiple splenic abscesses were subsequently identified. To reduce the risks of an additional surgical procedure in this particular patient, laparoscopic assisted splenotomy and catheter drainage were performed. Due to the severe complications that occurred in the present patient, no adjuvant chemotherapy was administered. Therefore, the unusual complication of splenic abscess subsequent to total gastrectomy should be noted, and the routine feeding jejunostomy tube placement at the time of total gastrectomy should be discussed and re-assessed.
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OBJECTIVE: To study the changes of morphology and function in rat hippocampus induced by high power microwave (HPM) radiation. METHODS: Fifty male Wistar rats were radiated by HPM. Then their learning and memory abilities were tested with Y maze and were sacrificed 6 h, 1 d, 3 d and 7 d after radiation. The hippocampus was taken out to study the basic pathologic changes, apoptosis and the expressions of neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP) by means of HE staining, Nissel body staining, in situ terminal end labeling and immunohistochemistry. RESULTS: The learning and memory abilities of rats reduced significantly after HPM radiation. HPM also resulted in rarefaction, edema and hemangiectasia of hippocampus, nervous cells degeneration and necrosis, decrease or disappearance of Nissel bodies. The injuries were more serious in field CA4 and dentate gyrus, which showed dose-effect relationship, and were progressively aggravated within 7 days. The apoptosis cells were significantly increased. NSE was increased in neurons. The NSE positive areas were also seen in the interstitial matrix and blood vessels. GFAP was increased in astrocytes, which became shorter and thicker. CONCLUSION: HPM can damage the abilities of learning and memory and results in morphologic changes in hippocampus. The major pathologic changes are degeneration, apoptosis and necrosis of neurons and edema in interstitium. NSE and GFAP play an important role in the pathologic process.
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Hipocampo/patologia , Hipocampo/efeitos da radiação , Memória/efeitos da radiação , Micro-Ondas/efeitos adversos , Animais , Apoptose/efeitos da radiação , Proteína Glial Fibrilar Ácida/metabolismo , Hipocampo/metabolismo , Aprendizagem/efeitos da radiação , Masculino , Fosfopiruvato Hidratase/metabolismo , Ratos , Ratos WistarRESUMO
The power absorbed by the human brain has possible implications in the study of the central nervous system-related biological effects of electromagnetic fields. In order to determine the specific absorption rate (SAR) of radio frequency (RF) waves in the human brain, and to investigate the effects of geometry and polarisation on SAR value, the finite-difference time-domain method was applied for the SAR computation. An anatomically realistic model scaled to a height of 1.70 m and a mass of 63 kg was selected, which included 14 million voxels segmented into 39 tissue types. The results suggested that high SAR values were found in the brain, i.e. â¼250 MHz for vertical polarisation and 900-1200 MHz both for vertical and horizontal polarisation, which may be the result of head resonance at these frequencies.
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Encéfalo/efeitos da radiação , Ondas de Rádio/efeitos adversos , Encéfalo/anatomia & histologia , Simulação por Computador , Campos Eletromagnéticos/efeitos adversos , Humanos , Modelos Anatômicos , Modelos Neurológicos , Doses de Radiação , Irradiação Corporal Total/efeitos adversosRESUMO
A set of conversion coefficients from kerma free-in-air to the organ absorbed dose for external photon beams from 10 keV to 10 MeV are presented based on a newly developed voxel mouse model, for the purpose of radiation effect evaluation. The voxel mouse model was developed from colour images of successive cryosections of a normal nude male mouse, in which 14 organs or tissues were segmented manually and filled with different colours, while each colour was tagged by a specific ID number for implementation of mouse model in Monte Carlo N-particle code (MCNP). Monte Carlo simulation with MCNP was carried out to obtain organ dose conversion coefficients for 22 external monoenergetic photon beams between 10 keV and 10 MeV under five different irradiation geometries conditions (left lateral, right lateral, dorsal-ventral, ventral-dorsal, and isotropic). Organ dose conversion coefficients were presented in tables and compared with the published data based on a rat model to investigate the effect of body size and weight on the organ dose. The calculated and comparison results show that the organ dose conversion coefficients varying the photon energy exhibits similar trend for most organs except for the bone and skin, and the organ dose is sensitive to body size and weight at a photon energy approximately <0.1 MeV.