Background The mechanical properties are related with many biological functions of cells. Accurate quantification of the mechanical properties of living cells require the combined use of experimental techniques and th...Background The mechanical properties are related with many biological functions of cells. Accurate quantification of the mechanical properties of living cells require the combined use of experimental techniques and theoretical models. Micropipette aspiration (MPA) is one of common techniques in determining mechanical properties of the living cells. The halfspace model (HSM) is employed in MPA technique. However,in the conditions of linear constitutive relations and small deformations,the HSM is inadequate for characterizing the MPA of a spherical cell in two respects. Firstly,the cell size is fairly finite other than semi-infinite to the inner radius of a micropipette;Secondly,cells are compressible,with a Poisson’s ratioνvarying from 0. 2 to 0. 4 (23-25) instead of incompressible (ν=0. 5). Thus,a more accurate model is necessary.In this study,the viscoelastic expressions were derived from our previous MPA test. Then,a sphere model (SM) employed to analyze mechanical properties of rabbit chondrocytes combined with the experimental data. Differences in mechanical properties estimated by different mechanical models were evaluated.Methods A sphere model (SM) was employed. The relative dimension of cell to micropipette and the compressibility of the cell were taken into account,as shown in Fig. 1a.■Fig.1 Sphere model of the MPA of a single cell employing different constitutive relationships The approximate expression for the aspirated length was obtained from our previous study as follows:■Furthermore,assuming that the cell behaves as a homogeneous and isotropic standard linear solid (Fig. 1b),two viscoelastic creep expressions of the aspirated length for incompressible sphere model (ICSM) and for compressible sphere model (CSM) were derived by elastic-viscoelastic correspondence principle and integral transformation as Eqs.(2) and (3)respectively.■Results(1) Comparisons of models The elastic modulus from the ICSM was 47. 4%higher than that of the half-space model (HSM)(P<0. 001). For the CSM,the percentage increase in E over the value for the HSM was 87. 7%,78. 9%,and 64. 9%when the Poisson’s ratio was set to 0. 2,0. 3,and 0. 4,respectively.For the viscoelasticity,the parameters for the ICSM and CSM were significantly larger than those of the HSM (P <0. 001). The k1,k2,andμfor the ICSM were 37. 8%,37. 9%,and 39. 0%higher,respectively,than those of the HSM. For the CSM,the viscoelastic parameters decreased with the increase ofν. Whenν=0. 3,k1,k2,andμincreased by 71. 0%,200%,and 157%,respectively,compared to those of the ICSM (P<0. 001);For the cases ofν=0. 2 andν=0. 4,the above parameters were respectively 102%,243%,and 209%and 35. 3%,97. 5%,and 79%higher than those of the ICSM.(2) Predictions for the relative errors of mechanical parameters caused by HSM e is defined as the relative change of elastic moduli (or relative error) between the HSM and SM. As shown in Fig. 2,when Poisson’s ratioνis 0. 3,in order to let the e less than 30%,relative dimension between the cell and the micropipetteξneeds to be at least 5. 0. Whenνequals 0. 5 (ICSM),ξis about 3. 3 to make the e reach 20%. However,ξis rarely larger than 5. 0 in general MPA experiments,thus the relative error of modulus will exceed 30%. The above results are independent of cell types,thus they are applicable to other spherical solid-like cells.■Fig.2 Thresholds ofξvarying withνwhen e was 10%,20%,and 30%,respectively Another parameter VR was introduced to represent the relative errors of viscoelastic parameters between HSM and SM.With regard to ICSM (Fig. 3a),whenξis 3,VRis nearly 22%. If theξis larger than 8. 0,the relative error will be reduced to less than 10%. For the CSM,the viscoelastic parameters of a typical chondrocyte varying withξandνwere obtained,as shown from Figs. 3b to 3d. Whenνtends to 0. 5,the parameters tend to those of ICSM. When theξexceeds 10,each parameter changes very little. For a certain Poisson’s ratio (ν=0. 3),whenξis 3,the VR of k1,k2,andμare 47. 1%,70. 8%,and 68. 2%,respectively. Whenξequals 5 and 10,the above values are 42. 3%,68. 8%,65%,and 38. 4%,66. 0%,63. 2%,respectively. For a givenξ(ξ=3),whenνis 0. 2,the VR of k1,k2,andμare 53. 6%,73. 3%,and 75. 0%,respectively.Whenνis taken as 0. 3 and 0. 4,the above errors are 47. 7%,71. 1%,68. 2%,and 38. 4%,58. 8%,54. 8%,respectively.Thus,the VR also decreases with the increase ofξandν.Conclusions The effects of the relative dimension between the cell,and micropipette and the Poisson’s ratio of cell were remarkable and should be taken into consideration in the pursuit of more accurate mechanical parameters of cells.展开更多
Objective:In recent years,the incidence and detection rate of pancreatic cystic lesions(PCLs)have increased significantly.Endoscopic ultrasound(EUS)plays an indispensable role in the diagnosis and differential diagnos...Objective:In recent years,the incidence and detection rate of pancreatic cystic lesions(PCLs)have increased significantly.Endoscopic ultrasound(EUS)plays an indispensable role in the diagnosis and differential diagnosis of PCLs.However,evidence comparing the diagnostic performance of EUS-guided fine-needle aspiration(EUS-FNA)and fine-needle biopsy(FNB)remains limited.This study aims to compare the diagnostic yield,adequacy of tissue acquisition,and safety between EUS-FNA and EUS-FNB in evaluating PCLs to inform clinical practice.Methods:A retrospective review was conducted on patients with PCLs who underwent either EUS-FNA or EUS-FNB between January 2014 and August 2021.The diagnostic yield,tissue acquisition adequacy,and incidence of adverse events were compared between the 2 groups.Results:A total of 90 patients with PCLs were included(52 in the FNA group and 38 in the FNB group).The diagnostic yield was similar between the FNA and FNB groups(94.2%vs 94.7%,P>0.05).The adequacy of tissue acquisition was 71.2%in the FNA group and 81.6%in the FNB group(P>0.05).No statistically significant difference was observed in the incidence of adverse events between the 2 groups(P>0.05).Conclusion:Both EUS-FNA and EUS-FNB demonstrate equally high diagnostic yields and tissue adequacy in PCLs,with excellent safety profiles.Both methods are safe and effective diagnostic tools for evaluating PCLs.展开更多
Transbronchial needle aspiration(TBNA)is able to provide definitive answers for a wide variety of pulmonary benign and malignant diseases including infectious diseases,cystic lesions,granulomatous diseases,pulmonary a...Transbronchial needle aspiration(TBNA)is able to provide definitive answers for a wide variety of pulmonary benign and malignant diseases including infectious diseases,cystic lesions,granulomatous diseases,pulmonary and mediastinal mass,etc.It’s proved particularly revolutionary to stage bronchogenic carcinoma during routine flexible bronchoscopy.What’s more,TBNA is an extremely safe procedure with no reported major complications.This review introduces the tech-niques about identifying the target,obtaining the specimen and preparing and interpreting the specimen when conducting TB-NA.The complications,a through unusual,and major limitations are also touched in this review.展开更多
文摘Background The mechanical properties are related with many biological functions of cells. Accurate quantification of the mechanical properties of living cells require the combined use of experimental techniques and theoretical models. Micropipette aspiration (MPA) is one of common techniques in determining mechanical properties of the living cells. The halfspace model (HSM) is employed in MPA technique. However,in the conditions of linear constitutive relations and small deformations,the HSM is inadequate for characterizing the MPA of a spherical cell in two respects. Firstly,the cell size is fairly finite other than semi-infinite to the inner radius of a micropipette;Secondly,cells are compressible,with a Poisson’s ratioνvarying from 0. 2 to 0. 4 (23-25) instead of incompressible (ν=0. 5). Thus,a more accurate model is necessary.In this study,the viscoelastic expressions were derived from our previous MPA test. Then,a sphere model (SM) employed to analyze mechanical properties of rabbit chondrocytes combined with the experimental data. Differences in mechanical properties estimated by different mechanical models were evaluated.Methods A sphere model (SM) was employed. The relative dimension of cell to micropipette and the compressibility of the cell were taken into account,as shown in Fig. 1a.■Fig.1 Sphere model of the MPA of a single cell employing different constitutive relationships The approximate expression for the aspirated length was obtained from our previous study as follows:■Furthermore,assuming that the cell behaves as a homogeneous and isotropic standard linear solid (Fig. 1b),two viscoelastic creep expressions of the aspirated length for incompressible sphere model (ICSM) and for compressible sphere model (CSM) were derived by elastic-viscoelastic correspondence principle and integral transformation as Eqs.(2) and (3)respectively.■Results(1) Comparisons of models The elastic modulus from the ICSM was 47. 4%higher than that of the half-space model (HSM)(P<0. 001). For the CSM,the percentage increase in E over the value for the HSM was 87. 7%,78. 9%,and 64. 9%when the Poisson’s ratio was set to 0. 2,0. 3,and 0. 4,respectively.For the viscoelasticity,the parameters for the ICSM and CSM were significantly larger than those of the HSM (P <0. 001). The k1,k2,andμfor the ICSM were 37. 8%,37. 9%,and 39. 0%higher,respectively,than those of the HSM. For the CSM,the viscoelastic parameters decreased with the increase ofν. Whenν=0. 3,k1,k2,andμincreased by 71. 0%,200%,and 157%,respectively,compared to those of the ICSM (P<0. 001);For the cases ofν=0. 2 andν=0. 4,the above parameters were respectively 102%,243%,and 209%and 35. 3%,97. 5%,and 79%higher than those of the ICSM.(2) Predictions for the relative errors of mechanical parameters caused by HSM e is defined as the relative change of elastic moduli (or relative error) between the HSM and SM. As shown in Fig. 2,when Poisson’s ratioνis 0. 3,in order to let the e less than 30%,relative dimension between the cell and the micropipetteξneeds to be at least 5. 0. Whenνequals 0. 5 (ICSM),ξis about 3. 3 to make the e reach 20%. However,ξis rarely larger than 5. 0 in general MPA experiments,thus the relative error of modulus will exceed 30%. The above results are independent of cell types,thus they are applicable to other spherical solid-like cells.■Fig.2 Thresholds ofξvarying withνwhen e was 10%,20%,and 30%,respectively Another parameter VR was introduced to represent the relative errors of viscoelastic parameters between HSM and SM.With regard to ICSM (Fig. 3a),whenξis 3,VRis nearly 22%. If theξis larger than 8. 0,the relative error will be reduced to less than 10%. For the CSM,the viscoelastic parameters of a typical chondrocyte varying withξandνwere obtained,as shown from Figs. 3b to 3d. Whenνtends to 0. 5,the parameters tend to those of ICSM. When theξexceeds 10,each parameter changes very little. For a certain Poisson’s ratio (ν=0. 3),whenξis 3,the VR of k1,k2,andμare 47. 1%,70. 8%,and 68. 2%,respectively. Whenξequals 5 and 10,the above values are 42. 3%,68. 8%,65%,and 38. 4%,66. 0%,63. 2%,respectively. For a givenξ(ξ=3),whenνis 0. 2,the VR of k1,k2,andμare 53. 6%,73. 3%,and 75. 0%,respectively.Whenνis taken as 0. 3 and 0. 4,the above errors are 47. 7%,71. 1%,68. 2%,and 38. 4%,58. 8%,54. 8%,respectively.Thus,the VR also decreases with the increase ofξandν.Conclusions The effects of the relative dimension between the cell,and micropipette and the Poisson’s ratio of cell were remarkable and should be taken into consideration in the pursuit of more accurate mechanical parameters of cells.
基金supported by the Special Project for the Construction of Innovative Provinces in Hunan Province,China(2020SK2013)。
文摘Objective:In recent years,the incidence and detection rate of pancreatic cystic lesions(PCLs)have increased significantly.Endoscopic ultrasound(EUS)plays an indispensable role in the diagnosis and differential diagnosis of PCLs.However,evidence comparing the diagnostic performance of EUS-guided fine-needle aspiration(EUS-FNA)and fine-needle biopsy(FNB)remains limited.This study aims to compare the diagnostic yield,adequacy of tissue acquisition,and safety between EUS-FNA and EUS-FNB in evaluating PCLs to inform clinical practice.Methods:A retrospective review was conducted on patients with PCLs who underwent either EUS-FNA or EUS-FNB between January 2014 and August 2021.The diagnostic yield,tissue acquisition adequacy,and incidence of adverse events were compared between the 2 groups.Results:A total of 90 patients with PCLs were included(52 in the FNA group and 38 in the FNB group).The diagnostic yield was similar between the FNA and FNB groups(94.2%vs 94.7%,P>0.05).The adequacy of tissue acquisition was 71.2%in the FNA group and 81.6%in the FNB group(P>0.05).No statistically significant difference was observed in the incidence of adverse events between the 2 groups(P>0.05).Conclusion:Both EUS-FNA and EUS-FNB demonstrate equally high diagnostic yields and tissue adequacy in PCLs,with excellent safety profiles.Both methods are safe and effective diagnostic tools for evaluating PCLs.
文摘Transbronchial needle aspiration(TBNA)is able to provide definitive answers for a wide variety of pulmonary benign and malignant diseases including infectious diseases,cystic lesions,granulomatous diseases,pulmonary and mediastinal mass,etc.It’s proved particularly revolutionary to stage bronchogenic carcinoma during routine flexible bronchoscopy.What’s more,TBNA is an extremely safe procedure with no reported major complications.This review introduces the tech-niques about identifying the target,obtaining the specimen and preparing and interpreting the specimen when conducting TB-NA.The complications,a through unusual,and major limitations are also touched in this review.
