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1.
J Obstet Gynaecol Res ; 46(4): 646-653, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32045956

RESUMO

AIM: To investigate the clinicopathologic characteristic and fertility results of patients with mucinous borderline ovarian tumors (MBOTs), and the effects of intraepithelial carcinoma (IECA) on them. METHODS: Fifty-two patients treated for MBOTs with or without IECA were retrospectively analyzed. RESULTS: Patients with IECA were more frequently observed at stage Ic (3/12 vs 1/40, P = 0.034) and accompanied by microinvasive carcinoma (3/12 vs 1/40, P = 0.034). The detected rate of IECA by intraoperative frozen section (5/12, 41.7%) was much lower than that of MBOTs (82.5%, P = 0.010). About 61.5% patients in our study underwent fertility-sparing surgery. Follow-up information was retained completely in 41 patients. And all four tumor recurrences were observed (9.8%) in conservative surgery group in 66 months, though there was no statistical association (P = 0.280). There were three patients who recurred more than once, even one occurred tumor-related death. Only one recurrent patient was in IECA group (P > 0.05). However, patients with IECA were more likely to receive adjuvant chemotherapy (3 of 12 vs 0 of 40, P = 0.010) and surgical staging (75% vs 52.5%, P = 0.200). As for fertility results, nine patients wished to be pregnant and seven of them (77.8%) were successful. CONCLUSION: For young patients with MBOTs, fertility results are satisfactory after conservative surgery. But patients should be fully informed about the relative high recurrent rate. And IECA has no statistical negative effects on MBOTs till now, but a long-term follow-up is required.


Assuntos
Adenocarcinoma Mucinoso/patologia , Carcinoma in Situ/patologia , Preservação da Fertilidade/estatística & dados numéricos , Fertilidade , Neoplasias Ovarianas/patologia , Adenocarcinoma Mucinoso/terapia , Adolescente , Adulto , Idoso , Carcinoma in Situ/terapia , Quimioterapia Adjuvante , Feminino , Preservação da Fertilidade/métodos , Humanos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/epidemiologia , Recidiva Local de Neoplasia/patologia , Estadiamento de Neoplasias , Neoplasias Ovarianas/terapia , Gravidez , Taxa de Gravidez , Estudos Retrospectivos , Resultado do Tratamento , Adulto Jovem
2.
Acta Radiol ; 61(9): 1266-1276, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31955611

RESUMO

BACKGROUND: Preoperative prediction of the recurrence of epithelial ovarian carcinoma (EOC) can guide the clinical treatment and improve the prognosis. However, there are still no reliable predictive biomarkers. PURPOSE: To evaluate whether whole solid tumor volume histogram parameters measured from quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can predict the recurrence in patients with EOC. MATERIAL AND METHODS: We followed up 56 patients with surgical and histopathologically diagnosed EOC who underwent quantitative DCE-MRI scans. The differences of the histogram parameters between patients with and without recurrence were compared. Mann-Whitney U test, Pearson's Chi-squared test, or Fisher's exact test, and receiver operating characteristic (ROC) curves were used for statistical analysis. RESULTS: All histogram parameters of Ktrans, kep, and ve were not significantly different between EOC patients with and without recurrence (P>0.05). For 30 patients with high-grade serous ovarian carcinoma (HGSOC), the histogram parameters of Ktrans (mean and 5th, 10th, 25th, 50th, 75th percentiles) and kep (mean and 50th percentile) in 12 patients with recurrence were significantly lower than those in 18 patients without recurrence (all P<0.05). ROC curves showed that the 5th percentile of Ktrans had the largest area under the curve (AUC) of 0.792 for predicting the recurrence in patients with HGSOC. When the threshold value was ≤0.0263/min, the sensitivity, specificity, and accuracy were 100%, 66.7%, and 80%, respectively. CONCLUSION: Instead of predicting the recurrence of EOC, whole solid tumor volume quantitative DCE-MRI histogram parameters could predict the recurrence of HGSOC and may be potential biomarkers for the prediction of HGSOC recurrence.


Assuntos
Carcinoma Epitelial do Ovário/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Recidiva Local de Neoplasia/diagnóstico por imagem , Neoplasias Ovarianas/diagnóstico por imagem , Adulto , Idoso , Carcinoma Epitelial do Ovário/patologia , Meios de Contraste , Estudos de Viabilidade , Feminino , Humanos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/patologia , Neoplasias Ovarianas/patologia , Valor Preditivo dos Testes , Carga Tumoral
3.
Abdom Radiol (NY) ; 43(11): 3132-3141, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29556691

RESUMO

PURPOSE: This study aimed to investigate the diagnostic performance of quantitative DCE-MRI for characterizing ovarian tumors. METHODS: We prospectively assessed the differences of quantitative DCE-MRI parameters (Ktrans, kep, and ve) among 15 benign, 28 borderline, and 66 malignant ovarian tumors; and between type I (n = 28) and type II (n = 29) of epithelial ovarian carcinomas (EOCs). DCE-MRI data were analyzed using whole solid tumor volume region of interest (ROI) method, and quantitative parameters were calculated based on a modified Tofts model. The non-parametric Kruskal-Wallis test, Mann-Whitney U test, Pearson's chi-square test, intraclass correlation coefficient (ICC), variance test, and receiver operating characteristic curves (ROC) were used for statistical analysis. RESULTS: The largest Ktrans and kep values were observed in ovarian malignant tumors, followed by borderline and benign tumors (all P < 0.001). Kep was the better parameter for differentiating benign tumors from borderline and malignant tumors, with a sensitivity of 89.3% and 95.5%, a specificity of 86.7% and 100%, an accuracy of 88.4% and 96.3%, and an area under the curve (AUC) of 0.94 and 0.992, respectively, whereas Ktrans was better for differentiating borderline from malignant tumors with a sensitivity of 60.7%, a specificity of 78.8%, an accuracy of 73.4%, and an AUC of 0.743. In addition, a combination with kep could further improve the sensitivity to 78.9%. The median Ktrans and kep values were significantly higher in type II than in type I EOCs. CONCLUSION: DCE-MRI with volume quantification is a technically feasible method, and can be used for the differentiation of ovarian tumors and for discriminating between type I and type II EOCs.


Assuntos
Imageamento por Ressonância Magnética/métodos , Neoplasias Ovarianas/diagnóstico por imagem , Neoplasias Ovarianas/patologia , Adolescente , Adulto , Idoso , Criança , Meios de Contraste , Diagnóstico Diferencial , Feminino , Humanos , Pessoa de Meia-Idade , Estudos Prospectivos , Sensibilidade e Especificidade
4.
Int J Gynecol Cancer ; 27(9): 1877-1887, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28906310

RESUMO

OBJECTIVE: This study aimed to investigate the conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) features of endometrial stromal sarcoma (ESS) including a preliminary investigation of the correlation between the apparent diffusion coefficient (ADC) value and Ki-67 expression. METHODS: The clinical and MRI data of 15 patients with ESS confirmed by surgery and pathology were analyzed retrospectively. The conventional MR morphological features, signal intensity on DWI, ADC value (n = 14), and clinicopathological marker Ki-67 (n = 13) were evaluated. RESULTS: Of 15 patients with ESS, 13 tumors were low-grade ESS (LGESS), and the remaining 2 were high-grade ESS (HGESS); 9 tumors were located in the myometrium, 5 were located in the endometrium and/or cervical canal, and 1 was located in extrauterine. Thirteen (87%) of 15 tumors showed a homo- or heterogeneous isointensity on T1-weighted imaging and a heterogeneous hyperintensity on T2-weighted imaging. The hypointense bands were observed in 11 tumors (73%) on T2-weighted imaging. The degenerations (cystic/necrosis/hemorrhage) were observed in 7 LGESS tumors and 2 HGESS tumors. The DWI hyperintensity was observed in 13 tumors (93%) and isointensity in remaining 1. The mean ADC value of the solid components in 14 ESSs was (1.05 ± 0.20) × 10mm/s. The contrast-enhanced MRI showed an obvious enhancement in 14 tumors (93%) (heterogeneous in 7 LGESSs and 2 HGESSs; homogeneous in 5 LGESSs). The ADC value was inversely correlated with the Ki-67 expression (r = -0.613, P = 0.026). CONCLUSIONS: Patients with ESS showed some characteristics on conventional MRI and DWI, and there was an inverse correlation between the ADC value and Ki-67 expression.


Assuntos
Neoplasias do Endométrio/diagnóstico por imagem , Neoplasias do Endométrio/metabolismo , Antígeno Ki-67/biossíntese , Sarcoma do Estroma Endometrial/diagnóstico por imagem , Sarcoma do Estroma Endometrial/metabolismo , Adulto , Idoso , Imagem de Difusão por Ressonância Magnética/métodos , Neoplasias do Endométrio/patologia , Feminino , Humanos , Pessoa de Meia-Idade , Sarcoma do Estroma Endometrial/patologia , Adulto Jovem
5.
J Magn Reson Imaging ; 46(5): 1499-1506, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28295854

RESUMO

PURPOSE: To investigate the use of diffusion kurtosis imaging (DKI) in differentiating borderline from malignant epithelial ovarian tumors (MEOTs) and to correlate DKI parameters with Ki-67 expression. MATERIALS AND METHODS: Fifty-two consecutive patients with epithelial ovarian tumors (17 borderline epithelial ovarian tumors, BEOTs; 35 MEOTs) were prospectively evaluated using DKI with b values of 0, 500, 1000, 1500, 2000, and 2500 s/mm2 and standard diffusion-weighted imaging (DWI) with b values of 0 and 1000 s/mm2 using a 1.5T magnetic resonance imaging (MRI) unit. The kurtosis (K) and diffusion coefficient (D) from DKI and apparent diffusion coefficient (ADC) from standard DWI were measured, compared, and correlated with Ki-67 expression between the two groups. Statistical analyses were performed using the Mann-Whitney U-test, receiver operating characteristic (ROC) curves, and Spearman's correlation. RESULTS: The K value was significantly lower in BEOTs than in MEOTs (0.55 ± 0.09 vs. 0.9 ± 0.2), while the D and ADC values were significantly higher in BEOTs than in MEOTs (2.27 ± 0.35 vs. 1.39 ± 0.37 and 1.72 ± 0.36 vs. 1.1 ± 0.25, respectively) (P < 0.001). For differentiating between BEOTs and MEOTs, the sensitivity, specificity, and accuracy were 88.2%, 94.3%, and 92.3% for K value; 88.2%, 91.4%, and 90.4% for D value; and 88.2%, 88.6%, and 88.5% for ADC value, respectively. However, there were no differences in the diagnostic performances among the three parameters above (K vs. ADC, P = 0.203; D vs. ADC, P = 0.148; K vs. D, P = 0.904). The K value was positively correlated with Ki-67 expression (r = 0.699), while the D and ADC values were negatively correlated with Ki-67 expression (r = -0.680, -0.665, respectively). CONCLUSION: Preliminary findings demonstrate that DKI is an alternative tool for differentiating BEOTs from MEOTs, and is correlated with Ki-67 expression. However, no added value is found for DKI compared with standard DWI. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1499-1506.


Assuntos
Imagem de Difusão por Ressonância Magnética , Imagem de Tensor de Difusão , Processamento de Imagem Assistida por Computador , Antígeno Ki-67/metabolismo , Neoplasias Epiteliais e Glandulares/diagnóstico por imagem , Neoplasias Epiteliais e Glandulares/metabolismo , Neoplasias Ovarianas/diagnóstico por imagem , Neoplasias Ovarianas/metabolismo , Adulto , Idoso , Carcinoma Epitelial do Ovário , Feminino , Humanos , Imuno-Histoquímica , Pessoa de Meia-Idade , Variações Dependentes do Observador , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Adulto Jovem
6.
J Biomech ; 45(16): 2769-77, 2012 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-23040882

RESUMO

In this study, a new cell density model was developed and incorporated into the formulation of the mechano-electrochemical mixture theory to investigate the effects of deprivation of nutrition supply at boundary source, degeneration, and dynamic loading on the cell viability of intervertebral disc (IVD) using finite element methods. The deprivation of nutrition supply at boundary source was simulated by reduction in nutrition level at CEP and AF boundaries. Cases with 100%, 75%, 60%, 50% and 30% of normal nutrition level at both CEP and AF boundaries were modeled. Unconfined axial sinusoidal dynamic compressions with different combinations of amplitude (u=10%± 2.5%, ± 5%) and frequency (f=1, 10, 20 cycle/day) were applied. Degenerated IVD was modeled with altered material properties. Cell density decreased substantially with reduction of nutrition level at boundaries. Cell death was initiated primarily near the NP-AF interface on the mid-plane. Dynamic loading did not result in a change in the cell density in non-degenerated IVD, since glucose levels did not fall below the minimum value for cell survival; in degenerated IVDs, we found that increasing frequency and amplitude both resulted in higher cell density, because dynamic compression facilitates the diffusion of nutrients and thus increases the nutrition level around IVD cells. The novel computational model can be used to quantitatively predict both when and where cells start to die within the IVD under various kinds of nutritional and mechanical conditions.


Assuntos
Disco Intervertebral/patologia , Desnutrição/patologia , Modelos Biológicos , Sobrevivência Celular , Cloretos/metabolismo , Análise de Elementos Finitos , Glucose/metabolismo , Humanos , Disco Intervertebral/fisiologia , Ácido Láctico/metabolismo , Desnutrição/metabolismo , Desnutrição/fisiopatologia , Oxigênio/metabolismo , Sódio/metabolismo , Estresse Mecânico
7.
Ann Biomed Eng ; 40(12): 2551-8, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22669503

RESUMO

The avascular intervertebral disc (IVD) receives nutrition via transport from surrounding vasculature; poor nutrition is believed to be a main cause of disc degeneration. In this study, we investigated the effects of mechanical deformation and anisotropy on the transport of two important nutrients--oxygen and glucose--in human annulus fibrosus (AF). The diffusivities of oxygen and glucose were measured under three levels of uniaxial confined compression--0, 10, and 20%--and in three directions--axial, circumferential, and radial. The glucose partition coefficient was also measured at three compression levels. Results for glucose and oxygen diffusivity in AF ranged from 4.46 × 10(-7) to 9.77 × 10(-6) cm(2)/s and were comparable to previous studies; the glucose partition coefficient ranged from 0.71 to 0.82 and was also similar to previous results. Transport properties were found to decrease with increasing deformation, likely caused by fluid exudation during tissue compression and reduction in pore size. Furthermore, diffusivity in the radial direction was lower than in the axial or circumferential directions, indicating that nutrient transport in human AF is anisotropic. This behavior is likely a consequence of the layered structure and unique collagen architecture of AF tissue. These findings are important for better understanding nutritional supply in IVD and related disc degeneration.


Assuntos
Glucose/metabolismo , Disco Intervertebral/metabolismo , Vértebras Lombares/metabolismo , Modelos Biológicos , Oxigênio/metabolismo , Compressão da Medula Espinal/metabolismo , Adulto , Transporte Biológico , Feminino , Humanos , Disco Intervertebral/fisiopatologia , Vértebras Lombares/fisiopatologia , Masculino , Pessoa de Meia-Idade , Compressão da Medula Espinal/fisiopatologia
9.
J Biomech Eng ; 133(9): 091006, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22010741

RESUMO

The intervertebral disc (IVD) receives important nutrients, such as glucose, from surrounding blood vessels. Poor nutritional supply is believed to play a key role in disc degeneration. Several investigators have presented finite element models of the IVD to investigate disc nutrition; however, none has predicted nutrient levels and cell viability in the disc with a realistic 3D geometry and tissue properties coupled to mechanical deformation. Understanding how degeneration and loading affect nutrition and cell viability is necessary for elucidating the mechanisms of disc degeneration and low back pain. The objective of this study was to analyze the effects of disc degeneration and static deformation on glucose distributions and cell viability in the IVD using finite element analysis. A realistic 3D finite element model of the IVD was developed based on mechano-electrochemical mixture theory. In the model, the cellular metabolic activities and viability were related to nutrient concentrations, and transport properties of nutrients were dependent on tissue deformation. The effects of disc degeneration and mechanical compression on glucose concentrations and cell density distributions in the IVD were investigated. To examine effects of disc degeneration, tissue properties were altered to reflect those of degenerated tissue, including reduced water content, fixed charge density, height, and endplate permeability. Two mechanical loading conditions were also investigated: a reference (undeformed) case and a 10% static deformation case. In general, nutrient levels decreased moving away from the nutritional supply at the disc periphery. Minimum glucose levels were at the interface between the nucleus and annulus regions of the disc. Deformation caused a 6.2% decrease in the minimum glucose concentration in the normal IVD, while degeneration resulted in an 80% decrease. Although cell density was not affected in the undeformed normal disc, there was a decrease in cell viability in the degenerated case, in which averaged cell density fell 11% compared with the normal case. This effect was further exacerbated by deformation of the degenerated IVD. Both deformation and disc degeneration altered the glucose distribution in the IVD. For the degenerated case, glucose levels fell below levels necessary for maintaining cell viability, and cell density decreased. This study provides important insight into nutrition-related mechanisms of disc degeneration. Moreover, our model may serve as a powerful tool in the development of new treatments for low back pain.


Assuntos
Análise de Elementos Finitos , Glucose/metabolismo , Degeneração do Disco Intervertebral/metabolismo , Degeneração do Disco Intervertebral/patologia , Disco Intervertebral/metabolismo , Disco Intervertebral/patologia , Fenômenos Mecânicos , Adulto , Calcinose/complicações , Contagem de Células , Sobrevivência Celular , Humanos , Degeneração do Disco Intervertebral/complicações , Masculino , Permeabilidade
10.
Cell Mol Bioeng ; 4(2): 302-310, 2011 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-21625336

RESUMO

Low back pain is associated with intervertebral disc degeneration. One of the main signs of degeneration is the inability to maintain extracellular matrix integrity. Extracellular matrix synthesis is closely related to production of adenosine triphosphate (i.e. energy) of the cells. The intervertebral disc is composed of two major anatomical regions: annulus fibrosus and nucleus pulposus, which are structurally and compositionally different, indicating that their cellular metabolisms may also be distinct. The objective of this study was to investigate energy metabolism of annulus fibrosus and nucleus pulposus cells with and without dynamic compression, and examine differences between the two cell types. Porcine annulus and nucleus tissues were harvested and enzymatically digested. Cells were isolated and embedded into agarose constructs. Dynamically loaded samples were subjected to a sinusoidal displacement at 2 Hz and 15% strain for 4 h. Energy metabolism of cells was analyzed by measuring adenosine triphosphate content and release, glucose consumption, and lactate/nitric oxide production. A comparison of those measurements between annulus and nucleus cells was conducted. Annulus and nucleus cells exhibited different metabolic pathways. Nucleus cells had higher adenosine triphosphate content with and without dynamic loading, while annulus cells had higher lactate production and glucose consumption. Compression increased adenosine triphosphate release from both cell types and increased energy production of annulus cells. Dynamic loading affected energy metabolism of intervertebral disc cells, with the effect being greater in annulus cells.

11.
Comput Methods Biomech Biomed Engin ; 14(2): 195-204, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21337225

RESUMO

The intervertebral disc (IVD) is avascular, receiving nutrition from surrounding vasculature. Theoretical modelling can supplement experimental results to understand nutrition to IVD more clearly. A new, 3D finite element model of the IVD was developed to investigate effects of endplate calcification and mechanical deformation on glucose distributions in IVD. The model included anatomical disc geometry, non-linear coupling of cellular metabolism with pH and oxygen concentration and strain-dependent properties of the extracellular matrix. Calcification was simulated by reducing endplate permeability (∼79%). Mechanical loading was applied based on in vivo disc deformation during the transition from supine to standing positions. Three static strain conditions were considered: supine, standing and weight-bearing standing. Minimum glucose concentrations decreased 45% with endplate calcification, whereas disc deformation led to a 4.8-63% decrease, depending on the endplate condition (i.e. normal vs. calcified). Furthermore, calcification more strongly affected glucose concentrations in the nucleus compared to the annulus fibrous region. This study provides important insight into nutrient distributions in IVD under mechanical deformation.


Assuntos
Calcificação Fisiológica , Glucose/metabolismo , Disco Intervertebral/metabolismo , Análise de Elementos Finitos , Humanos , Imageamento Tridimensional , Modelos Teóricos
12.
Ann Biomed Eng ; 39(1): 53-65, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20686922

RESUMO

Several solutes (e.g., growth factors, cationic solutes, etc.) can reversibly bind to the extracellular matrix (ECM) of biological tissues. Binding interactions have significant implications on transport of such solutes through the ECM. In order to fully delineate transport phenomena in biological tissues, knowledge of binding kinetics is crucial. In this study, a new method for the simultaneous determination of solute anisotropic diffusivity and binding reaction rates was presented. The new technique was solely based on Fourier analysis of fluorescence recovery after photobleaching (FRAP) images. Computer-simulated FRAP tests were used to assess the sensitivity and the robustness of the method to experimental parameters, such as anisotropic solute diffusivity and rates of binding reaction. The new method was applied to the determination of diffusivity and binding rates of 5-dodecanoylaminofluorescein (DAF) in bovine coccygeal annulus fibrosus (AF). Our findings indicate that DAF reversibly binds to the ECM of AF. In addition, it was found that DAF diffusion in AF is anisotropic. The results were in agreement with those reported in previous studies. This study provides a new tool for the simultaneous determination of solute anisotropic diffusion tensor and rates of binding reaction that can be used to investigate diffusive-reactive transport in biological tissues and tissue engineered constructs.


Assuntos
Proteínas da Matriz Extracelular/química , Matriz Extracelular/química , Recuperação de Fluorescência Após Fotodegradação/métodos , Animais , Anisotropia , Bovinos , Difusão , Ligação Proteica , Solubilidade
13.
Ann Biomed Eng ; 37(12): 2566-73, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19757059

RESUMO

A new method for measuring the fixed charge density (FCD) in intervertebral disc (IVD) tissues employing a two-point electrical conductivity approach was developed. In this technique, the tissue is first confined and equilibrated in a potassium chloride (KCl) solution, and the tissue conductivity is then measured. This is then repeated with a second concentration of KCl solution. The FCD can be determined from the conductivity measurements. Using this method, the FCD values of bovine annulus fibrosus (AF) and nucleus pulposus (NP) tissues were determined to be 0.060 +/- 0.027 mEq/g wet tissue and 0.19 +/- 0.039 mEq/g wet tissue, respectively. The FCD of AF was significantly lower than that of NP tissue, similar to results in the literature for human IVD tissues. In order to verify the accuracy of the new method, the glycosaminoglycan (GAG) contents of the tissues were measured and used to estimate the tissue FCD. A strong correlation (R (2) = 0.84-0.87) was found to exist between FCD values measured and those estimated from GAG contents, indicating that the conductivity approach is a reliable technique for measuring the FCD of IVD tissues.


Assuntos
Disco Intervertebral/fisiologia , Vértebras Lombares/fisiologia , Pletismografia de Impedância/instrumentação , Animais , Bovinos , Condutividade Elétrica , Desenho de Equipamento , Análise de Falha de Equipamento , Técnicas In Vitro , Eletricidade Estática
14.
J Orthop Res ; 27(12): 1625-30, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19489044

RESUMO

Poor nutritional supply to the intervertebral disc is believed to be an important factor leading to disc degeneration. However, little is known regarding nutritional transport in human annulus fibrosus (AF) and its relation to tissue morphology. We hypothesized that solute diffusivity in human AF is anisotropic and inhomogeneous, and that transport behaviors are associated with tissue composition and structure. To test these hypotheses, we measured the direction-dependent diffusivity of a fluorescent molecule (fluorescein, 332 Da) in three regions of AF using a fluorescence recovery after photobleaching (FRAP) technique, and associated transport results to the regional variation in water content and collagen architecture in the tissue. Diffusivity in AF was anisotropic, with higher values in the axial direction than in the radial direction for all regions investigated. The values of the diffusion coefficient ranged from 0.38 +/- 0.25 x 10(-6) cm(2)/s (radial diffusivity in outer AF) to 2.68 +/- 0.84 x 10(-6) cm(2)/s (axial diffusivity in inner AF). In both directions, diffusivity decreased moving from inner to outer AF. Tissue structure was investigated using both scanning electron microscopy and environmental scanning electron microscopy. A unique arrangement of microtubes was found in human AF. Furthermore, we also found that the density of these microtubes varied moving from inner to outer AF. A similar trend of regional variation was found for water content, with the highest value also measured in inner AF. Therefore, we concluded that a relationship exists among the anisotropic and inhomogeneous diffusion in human AF and the structure and composition of the tissue.


Assuntos
Disco Intervertebral/metabolismo , Disco Intervertebral/ultraestrutura , Adulto , Animais , Anisotropia , Transporte Biológico Ativo , Bovinos , Colágeno/análise , Colágeno/ultraestrutura , Difusão , Fluoresceína/metabolismo , Recuperação de Fluorescência Após Fotodegradação/métodos , Humanos , Disco Intervertebral/química , Vértebras Lombares , Microscopia Eletrônica de Varredura , Microtúbulos/ultraestrutura , Pessoa de Meia-Idade , Água/análise
15.
J Biomech Eng ; 131(5): 054505, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19388789

RESUMO

The intervertebral disk (IVD), characterized as a charged, hydrated soft tissue, is the largest avascular structure in the body. Mechanical loading to the disk results in electromechanical transduction phenomenon as well as altered transport properties. Electrical conductivity is a material property of tissue depending on ion concentrations and diffusivities, which are in turn functions of tissue composition and structure. The aim of this study was to investigate the effect of mechanical loading on electrical behavior in human IVD tissues. We hypothesized that electrical conductivity in human IVD is strain-dependent, due to change in tissue composition caused by compression, and inhomogeneous, due to tissue structure and composition. We also hypothesized that conductivity in human annulus fibrosus (AF) is anisotropic, due to the layered structure of the tissue. Three lumbar IVDs were harvested from three human spines. From each disk, four AF specimens were prepared in each of the three principal directions (axial, circumferential, and radial), and four axial nucleus pulposus (NP) specimens were prepared. Conductivity was determined using a four-wire sense-current method and a custom-designed apparatus by measuring the resistance across the sample. Resistance measurements were taken at three levels of compression (0%, 10%, and 20%). Scanning electron microscopy (SEM) images of the human AF tissue were obtained in order to correlate tissue structure with conductivity results. Increasing compressive strain significantly decreased conductivity for all groups (p<0.05, analysis of variance (ANOVA)). Additionally, specimen orientation significantly affected electrical conductivity in the AF tissue, with conductivity in the radial direction being significantly lower than that in the axial or circumferential directions at all levels of compressive strain (p<0.05, ANOVA). Finally, conductivity in the NP tissue was significantly higher than that in the AF tissue (p<0.05, ANOVA). SEM images of the AF tissues showed evidence of microtubes orientated in the axial and circumferential directions, but not in the radial direction. This may suggest a relationship between tissue morphology and the anisotropic behavior of conductivity in the AF. The results of this investigation demonstrate that electrical conductivity in human IVD is strain-dependent and inhomogeneous, and that conductivity in the human AF tissue is anisotropic (i.e., direction-dependent). This anisotropic behavior is correlated with tissue structure shown in SEM images. This study provides important information regarding the effects of mechanical loading on solute transport and electrical behavior in IVD tissues.


Assuntos
Condutividade Elétrica , Disco Intervertebral/fisiologia , Anisotropia , Fenômenos Biomecânicos , Água Corporal/química , Força Compressiva/fisiologia , Humanos , Disco Intervertebral/ultraestrutura , Microscopia Eletrônica de Varredura , Resistência à Tração/fisiologia
16.
Ann Biomed Eng ; 37(4): 813-23, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19224367

RESUMO

In this study, a new method for determination of an anisotropic diffusion tensor by a single fluorescence recovery after photobleaching (FRAP) experiment was developed. The method was based on two independent analyses of video-FRAP images: the fast Fourier transform and the Karhunen-Loève transform. Computer-simulated FRAP tests were used to evaluate the sensitivity of the method to experimental parameters, such as the initial size of the bleached spot, the choice of the frequencies used in the Fourier analysis, the orientation of the diffusion tensor, and experimental noise. The new method was also experimentally validated by determining the anisotropic diffusion tensor of fluorescein (332 Da) in bovine annulus fibrosus. The results obtained were in agreement with those reported in a previous study. Finally, the method was used to characterize fluorescein diffusion in bovine meniscus. Our findings indicate that fluorescein diffusion in bovine meniscus is anisotropic. This study provides a new tool for the determination of anisotropic diffusion tensor that could be used to investigate the correlation between the structure of biological tissues and their transport properties.


Assuntos
Cartilagem/metabolismo , Diagnóstico por Imagem/métodos , Recuperação de Fluorescência Após Fotodegradação/métodos , Animais , Anisotropia , Bovinos , Cóccix/citologia , Simulação por Computador , Interpretação Estatística de Dados , Difusão , Fluoresceína/metabolismo , Corantes Fluorescentes/metabolismo , Análise de Fourier , Disco Intervertebral/citologia , Disco Intervertebral/metabolismo , Modelos Biológicos , Modelos Estatísticos , Análise Numérica Assistida por Computador , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Soluções
17.
Cell Mol Bioeng ; 2(2): 264-273, 2009 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-20161070

RESUMO

The objective of this study was to develop and demonstrate the utility of a novel method of evaluating intracellular levels of extracellular matrix (ECM) components in intervertebral disc (IVD) cells using flow cytometry. By using this method, this study discriminated between cell populations in porcine IVD and examined the response of IVD cells to monolayer cultures, a traditional method of cell expansion, by measuring phenotypic attributes of ECM component production. It was found that monolayer cultures affected collagen production of IVD cells while there were differences in collagen type II production between the cells isolated from the annulus fibrosus (AF) and nucleus pulposus (NP) regions of IVD. Size distributions of fresh and cultured cells were also presented while the relationships between cell size and intracellular collagen level revealed heterogeneous cell populations in AF and NP regions. Furthermore, this study showed that the intracellular collagen signals of IVD cells were significantly enhanced by the treatments of Brefeldin-A and ascorbic acid. This suggests that Brefeldin-A and ascorbic acid could be used to increase the sensitivity of flow cytometric analysis on intracellular collagen levels by maximizing collagen accumulation inside cells. Since a unique feature of the flow cytometric screening tool is the ability to discriminate between various cell populations in a single sample, the flow cytometric method developed in this study may have the potential to identify specific collagen-producing cell populations from tissues or cell cultures.

18.
J Biomech ; 41(6): 1184-96, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18374341

RESUMO

The objective of this study was to examine the effects of mechanical compression on metabolism and distributions of oxygen and lactate in the intervertebral disc (IVD) using a new formulation of the triphasic theory. In this study, the cellular metabolic rates of oxygen and lactate were incorporated into the newly developed formulation of the mechano-electrochemical mixture model [Huang, C.-Y., Gu, W.Y., 2007. Effect of tension-compression nonlinearity on solute transport in charged hydrated fibrosus tissues under dynamic unconfined compression. Journal of Biomechanical Engineering 129, 423-429]. The model was used to numerically analyze metabolism and transport of oxygen and lactate in the IVD under static or dynamic compression. The theoretical analyses demonstrated that compressive loading could affect transport and metabolism of nutrients. Dynamic compression increased oxygen concentration, reduced lactate accumulation, and promoted oxygen consumption and lactate production (i.e., energy conversion) within the IVD. Such effects of dynamic loading were dependent on strain level and loading frequency, and more pronounced in the IVD with less permeable endplate. In contrast, static compression exhibited inverse effects on transport and metabolism of oxygen and lactate. The theoretical predictions in this study are in good agreement with those in the literature. This study established a new theoretical model for analyzing cellular metabolism of nutrients in hydrated, fibrous soft tissues under mechanical compression.


Assuntos
Disco Intervertebral/metabolismo , Ácido Láctico/metabolismo , Vértebras Lombares/metabolismo , Modelos Biológicos , Oxigênio/metabolismo , Concentração de Íons de Hidrogênio , Estresse Mecânico
19.
Spine (Phila Pa 1976) ; 32(19): 2063-9, 2007 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-17762806

RESUMO

STUDY DESIGN: Investigation of the effects of low glucose concentrations on the oxygen consumption rates of intervertebral disc cells. OBJECTIVES: To determine the oxygen consumption rate of porcine anulus fibrosus (AF) cells at different glucose concentrations and to examine the differences in the oxygen consumption rate between AF and nucleus pulposus (NP) cells at different glucose levels. SUMMARY OF BACKGROUND DATA: Poor nutrient supply has been suggested as a potential mechanism for degeneration of the intervertebral disc (IVD). Distribution of nutrients in the IVD is strongly dependent on transport properties of the tissue and cellular metabolic rates. Previous studies have shown dependence of oxygen consumption rate of IVD cells on oxygen tension, pH levels, and glucose levels outside the physiologic range. However, the oxygen consumption rate of AF cells at in vivo glucose levels has not been investigated. METHODS: IVD cells were isolated from the outer AF and NP of 4- to 5-month-old porcine lumbar discs. The changes in oxygen tension were recorded when cells were cultured in sealed metabolism chamber. The oxygen consumption rate of cells was determined by theoretical curve fitting using the Michaelis-Menten equation. RESULTS: The outer AF cells cultured in high glucose medium (25 mmol/L) exhibited the lowest oxygen consumption rate, whereas no significant differences in oxygen consumption rates were found among outer AF cells cultured at physiologic glucose levels (i.e., 1 mmol/L, 2.5 mmol/L, 5 mmol/L). The oxygen consumption rate of NP cells was significantly greater than that of outer AF cells. CONCLUSION: Since the oxygen consumption rates determined in this study are comparable to the findings in the literature, this study has developed a new alternative method for determining oxygen consumption rate. The oxygen consumption rates of IVD cells reported in this study will be valuable for theoretically predicting local oxygen concentrations in IVD, which can provide a better understanding of transport of oxygen in the discs.


Assuntos
Glucose/metabolismo , Disco Intervertebral/metabolismo , Consumo de Oxigênio , Oxigênio/metabolismo , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Glucose/farmacologia , Disco Intervertebral/citologia , Disco Intervertebral/efeitos dos fármacos , Vértebras Lombares , Modelos Biológicos , Consumo de Oxigênio/efeitos dos fármacos , Reprodutibilidade dos Testes , Suínos
20.
Ann Biomed Eng ; 35(10): 1739-48, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17605108

RESUMO

The annulus fibrosus (AF) of the intervertebral disc (IVD) exhibits a fiber-organized structure which is responsible for anisotropic and inhomogeneous mechanical and transport properties. Due to its particular morphology, nutrient transport within AF is regulated by complex transport kinetics. This work investigates the diffusive transport of a small solute in the posterior and anterior regions of AF since diffusion is the major transport mechanism for low molecular weight nutrients (e.g., oxygen and glucose) in IVD. Diffusion coefficient (D) of fluorescein (332 Da) in bovine coccygeal AF was measured in the three major (axial, circumferential, and radial) directions of the IVD by means of fluorescence recovery after photobleaching (FRAP) technique. It was found that the diffusion coefficient was anisotropic and inhomogeneous. In both anterior and posterior regions, the diffusion coefficient in the radial direction was found to be the lowest. Circumferential and axial diffusion coefficients were not significantly different in both posterior and anterior regions and their values were about 130% and 150% the value of the radial diffusion coefficient, respectively. The values of diffusion coefficients in the anterior region were in general higher than those of corresponding diffusion coefficients in the posterior region. This study represents the first quantitative analysis of anisotropic diffusion transport in AF by means of FRAP technique and provides additional knowledge on understanding the pathways of nutritional supply into IVD.


Assuntos
Líquidos Corporais/metabolismo , Recuperação de Fluorescência Após Fotodegradação/métodos , Disco Intervertebral/citologia , Disco Intervertebral/fisiologia , Modelos Biológicos , Animais , Anisotropia , Transporte Biológico Ativo , Bovinos , Simulação por Computador , Difusão , Técnicas In Vitro
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