Reemergence of JAK2 V617F clone heralds extramedullary leukemia relapse after BMT for transformed essential thrombocytosis.
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Bone Marrow Transplantation↗
Biomedical subjects
K Y Lam
Publications and source records attributed to K Y Lam.
Transformed essential thrombocytosis with a JAK2 V617F mutation relapsing as JAK2 mutation-negative leukaemia after allogeneic stem cell transplantation.
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Cell Transformation, Neoplastic↗
Transient simulation of kinetics of electric-sensitive hydrogels.
Kinetics of the hydrogels responsive to electric stimulus due to an externally applied electric field is modeled for the first time through transient simulation. The mathematical model employed is called the multi-effect-coupling electric-stimulus (MECe) model, which is developed with consideration of multi-phases and multi-physics. Transient simulation by the MECe model is examined with available experimental data and good agreement is achieved. The kinetics of ionic concentration of diffusive species is simulated. The simulation also predicts the influences of several important parameters on the hydrogel deformation, including the externally applied electric voltage, initially fixed charge density and surrounding bath solution concentration.
Biosensing Techniques↗
Modeling and simulation of deformation of hydrogels responding to electric stimulus.
A model for simulation of pH-sensitive hydrogels is refined in this paper to extend its application to electric-sensitive hydrogels, termed the refined multi-effect-coupling electric-stimulus (rMECe) model. By reformulation of the fixed-charge density and consideration of finite deformation, the rMECe model is able to predict the responsive deformations of the hydrogels when they are immersed in a bath solution subject to externally applied electric field. The rMECe model consists of nonlinear partial differential governing equations with chemo-electro-mechanical coupling effects and the fixed-charge density with electric-field effect. By comparison between simulation and experiment extracted from literature, the model is verified to be accurate and stable. The rMECe model performs quantitatively for deformation analysis of the electric-sensitive hydrogels. The influences of several physical parameters, including the externally applied electric voltage, initial fixed-charge density, hydrogel strip thickness, ionic strength and valence of surrounding solution, are discussed in detail on the displacement and average curvature of the hydrogels.
Computer Simulation↗
A transient simulation to predict the kinetic behavior of hydrogels responsive to electric stimulus.
A kinetic analysis of the response of electric-sensitive hydrogels to an externally applied electric field is conducted for the first time through modeling and transient simulation. This model, called the multieffect coupling electric stimulus (MECe), considers the effects of multiphases and multiphysics. Its extended application to transient simulation is validated against available experimental data, and good agreement is achieved. The concentration kinetics of ionic species is simulated. The simulation predicts the kinetic behavior of the hydrogels with consideration of the influences of important parameters such as the electric potential, fixed-charge density, bath solution concentration, and hydrogel average curvature.
Computer Simulation↗
Multiphysics modelling of volume phase transition of ionic hydrogels responsive to thermal stimulus.
This paper presents the analysis of the volume phase transition of ionic thermo-sensitive hydrogels to thermal stimulus through mathematical modelling. The model is termed the multi-effect-coupling thermal-stimulus (MECtherm) model and it considers the effects of multi-phases and multi-physics. Its application to steady-state analysis of the hydrogels in swelling equilibrium is validated against available experimental data for the relation between volume swelling ratio and temperature, in which very good agreement is achieved. The phenomenon of volume phase transition is studied for the thermal-stimulus responsive hydrogel. The numerical studies predict well the influences of initially fixed charge density and initial volume fraction of polymeric network on the swelling equilibrium of the hydrogels.
Algorithms↗
Simulation of the influences of bathing solution and crosslink density on the swelling equilibrium of ionic thermo-sensitive hydrogels.
The influences of the bathing solution and crosslink density on the swelling equilibrium of ionic thermo-sensitive hydrogels due to temperature stimulus are studied by mathematical modeling. The model used is termed the multi-effect-coupling thermal-stimulus (MECtherm) model with consideration of multiphases and multiphysics. It is used for the steady-state numerical simulation of the hydrogels in swelling equilibrium after it is verified well by comparison with available experimental data concerning the variation of volume swelling ratio with temperature. The phenomenon of volume phase transition is simulated for the thermal-stimulus responsive hydrogel. Simulations predict well the influences of the bathing solution concentration and crosslink density of polymeric network on the swelling equilibrium of the hydrogels.
Chemical Phenomena↗
Model development and numerical simulation of electric-stimulus-responsive hydrogels subject to an externally applied electric field.
Based on a multi-phasic mixture theory with consideration of ionic diffusion and convection, a multi-physic model, called the multi-effect-coupling electric-stimulus (MECe) model, is developed for simulation of responsive behavior of the electric-sensitive hydrogels when they are immersed into a bathing solution subject to an externally applied electric field. In the developed model, with chemo-electro-mechanical coupling effects, the convection-diffusion equations for concentration distribution of diffusive ions incorporate the influence of electric potential. The electroneutrality condition is replaced by the Poisson equation for distribution of electric potential. The steady and transient analyses of hydrogel deformation are easily carried out by the continuity and momentum equations of the mixture phase. Further, the computational domain of the present model covers both the hydrogel and the surrounding solution. In order to solve the present mathematical model consisting of multi-field coupled nonlinear partial differential governing equations, a hierarchical iteration technique is proposed and a meshless Hermite-Cloud method (HCM) is employed. The steady-state simulation of the electric-stimulus responsive hydrogel is numerically conducted when it is subjected to an externally applied electric field. The hydrogel deformation and the ionic concentrations as well as electric potentials of both the hydrogel and external solution are investigated. The parameter influences on the swelling behaviors of the hydrogel are also discussed in detail. The simulating results are in good agreement with the experimental data and they validate the presently developed model.
Biosensing Techniques↗
Tissue transglutaminase catalyzes the formation of alpha-synuclein crosslinks in Parkinson's disease.
In Parkinson's disease (PD), conformational changes in the alpha-synuclein monomer precede the formation of Lewy bodies. We examined postmortem PD and undiseased (control) substantia nigra for evidence of pathological crosslinking of alpha-synuclein by tissue transglutaminase (tTG) using immunohistochemistry, immunoprecipitation, and Western blot. Consistent with previous reports, we found that both tTG and its substrate-characteristic N(epsilon)-(gamma-glutamyl)-lysine crosslink are increased in PD nigral dopamine neurons. Furthermore, both the tTG protein and its substrate crosslink coprecipitated with alpha-synuclein in extracts of PD substantia nigra. Unexpectedly, the isodipeptide crosslink was detected in the alpha-synuclein monomer as well as in higher molecular mass oligomers of alpha-synuclein. Although the intramolecularly crosslinked alpha-synuclein monomer was present in control tissue, it was highly enriched in PD substantia nigra. Conversely, significantly less uncrosslinked alpha-synuclein remained in the postimmunoprecipitate lysate of PD tissue than in control. Crosslinked alpha-synuclein, formed at the expense of the total alpha-synuclein monomer, correlated with disease progression. These results demonstrate that much of the alpha-synuclein monomer in PD nigra is crosslinked by tTG and thus may be functionally impaired. This modification appears to be an early step in PD pathogenesis, preceding the aggregation of alpha-synuclein in Lewy bodies.
Adult↗
Inflammatory fibroid polyp of the caecum in a patient with neurofibromatosis.
INTRODUCTION: Inflammatory fibroid polyp of the large intestine is uncommon. To our knowledge, this condition has not been reported in a patient with neurofibromatosis. CLINICAL PICTURE: In this report, a 66-year-old woman with neurofibromatosis was found to have a large polyp in the caecum. TREATMENT: Right hemicolectomy was performed because of the size of the polyp. OUTCOME: Pathological examination showed that the polyp was an inflammatory fibroid polyp. CONCLUSION: Clinicians should be aware that inflammatory fibroid polyps could be one of the many manifestations of neurofibromatosis in the gastrointestinal tract.
Aged↗
Image analysis system for assessment of immunohistochemically stained proliferative marker (MIB-1) in oesophageal squamous cell carcinoma.
The prognosis of oesophageal cancer patients is related to the portion of MIB-1 positively stained tumour nuclei. In this study, an image analysis system was developed based on LEICA Image Processing and Analysis System to reduce the subjective, tedious and inaccurate manual counting of nuclei staining. Representative oesophageal cancer tissues were collected and immunohistochemical preparations of MIB-1 were made. The MIB-1 positive nuclei in these tumours were assessed by quantitative counting, semi-quantitative counting, and three computer assessment methods using LEICA QWIN PRO. Our results showed that computer assessment methods were reliable and consistent. The procedure using the system could be accomplished within 15 min. Overlapped or missed counting of nuclei by the observer were eliminated. The image analysis system can really assist experts in obtaining reliable data for the prognosis of oesophageal cancer patients quickly.
Biomarkers↗
Constitutive model development and micro-structural topology optimisation for nafion hydrogel membranes with ionic clustering.
The deployment of electroactive ionic polymer hydrogel-metal composites in artificial muscle and BioMEMS applications has recently been intensively investigated. In order to analyse their electromechanical responses to externally applied electrical fields, it is critical to develop a constitutive model linking the macro-mechanical moduli with the micro-mechanical characteristics, and to determine the geometric size and shape of the micro-structural cluster and investigate the effect of cluster morphology on the effective electro-elastic moduli of the polymer hydrogels. As a typical ionic polymer-based hydrogel, the Nafion membrane is studied in this work. Based on the Biot poroelasticity theory, a multi-scale constitutive model which includes both macro and micro characteristics is developed using an asymptotic homogenisation method. The effect of water-volume fraction on the effective elastic moduli of the hydrogel membrane is examined for different equivalent weights. Numerical investigations show that the simulated effective constitutive moduli agree well with experimental data. The presently developed constitutive model is thus validated. In order to determine the micro-structural shape of the polymer skeleton subject to fluid pressure, a representative volume element (RVE) is designed by topology optimisation of the periodic microstructures of the Nafion hydrogels, through the minimisation of the electro-elastic interaction energy between the polymer-based fluorocarbon matrix and the surrounding fluid. This optimal RVE correctly predicts the geometric shapes of the clusters.
Compressive Strength↗
Biodynamic response of shipboard sitting subject to ship shock motion.
Underwater shock can produce very high accelerations, resulting in severe human injuries. In this paper, a shock-structure-human interaction model is proposed to study the biodynamic response of a shipboard sitting subject to ship motion induced by underwater shock (ship shock motion) wherein, the human body is modeled using a lumped parameter system with the parameters obtained from dynamic tensile tests. The results obtained from the human model used in this paper and living human drop test are also compared. Numerical results have revealed the characteristics of human response to ship shock motion. The part in direct contact with the structure (like the pelvis) is much more vulnerable than other parts (like the head). The influences of structural damping and stiffness on the peak loads acting on the human body are investigated. Both damping and stiffness have important influences on the pelvis, but have much less influences on other parts. Injury criteria in the literature are also summarized to facilitate injury assessment.
Biomechanical Phenomena↗
Clinicopathologic significance of bcl-2 expression in the surgical treatment of oral tongue carcinoma.
AIM: There is still controversy on the incidence of positive expression of bcl-2 and its prognostic significance for oral tongue carcinoma patients who are treated by surgery. The present study aims at resolving the controversy on the clinicopathologic significance of bcl-2 in a well selected group of patients who satisfy the recruitment criteria: (1) oral tongue carcinoma, (2) squamous cell carcinoma, (3) primary surgical treatment. METHOD: Bcl-2 expression was studied by immunohistochemistry on glossectomy specimens of 73 patients. The expression of bcl-2 was correlated with clinicopathologic data. RESULTS: Of the 73 tumours, 11% had positive expression of bcl-2. Bcl-2 expression was not significantly correlated with tumour grade, stage, nodal metastasis and survival. CONCLUSION: Bcl-2 expression played a minor role in oral tongue carcinoma. It had no significant correlation with tumour grade, stage and nodal metastasis. It also had no prognostic value on survival for patients who were treated by primary surgery.
Adolescent↗
E-cadherin expression is commonly downregulated by CpG island hypermethylation in esophageal carcinoma cells.
E-cadherin, a cell adhesion molecule, is regarded as an invasion-suppressor molecule and a prognostic marker in many types of human cancers. Downregulation of E-cadherin is common in esophageal carcinoma and is associated with an increase in invasive and metastatic potential. To study the mechanisms responsible for inactivation of this gene in esophageal squamous cell carcinoma (ESCC), we investigated the methylation status around the 5' promoter region of E-cadherin gene of six ESCC cell lines by methylation-specific polymerase chain reaction, and compared it with E-cadherin protein and mRNA expression. We also studied the methylation status of 20 ESCC clinical specimens. Methylation was noted in four of the six cell lines (one fully methylated and three partially methylated). The completely methylated cell line lacked E-cadherin protein expression and mRNA transcription. E-cadherin expression and transcription were reduced in a partially methylated cell line but preserved in the other partially methylated cell lines. Treatment of E-cadherin-negative carcinoma cells with the demethylating agent, 5-aza-2'-deoxycytidine, induced re-expression of the gene. A high frequency of methylation (16/20, 80%) was also noted in the 20 ESCC clinical samples. Our results indicate that 5' CpG island methylation is common in esophageal carcinoma and may play an important role in downregulation of E-cadherin.
Azacitidine↗
Cushing's syndrome secondary to adrenal adenoma during pregnancy.
Cushing's syndrome during pregnancy is rare because of the suppressive effect of excessive glucocorticoid on the female reproductive system. Adrenal adenoma is the most common cause of Cushing's syndrome during pregnancy. Surgical treatment by unilateral adrenalectomy was preferred during pregnancy before the advent of laparoscopic adrenalectomy. We describe two patients with Cushing's syndrome secondary to adrenal adenoma diagnosed during the first and second trimester, respectively, and successfully managed by different approaches of laparoscopic adrenalectomy--one patient upon diagnosis and one after pregnancy.
Adenoma↗
Digital gangrene and a mass in the heart.
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Endocarditis↗
Establishment and characterization of a new xenograft-derived human esophageal squamous cell carcinoma cell line SLMT-1 of Chinese origin.
A new human esophageal cancer cell line, named SLMT-1, was established from a nude-mouse xenograft of a well-differentiated esophageal squamous cell carcinoma (ESCC) of the lower esophagus from a male Hong Kong Chinese patient. SLMT-1, passaged over 34 times and with a doubling time of 31 hours, has the microscopic features of epithelial cells with adherent growth as a monolayer. The general biologic properties of SLMT-1 cells were characterized by (1) a positive test of tumorigenicity obtained by injecting cells subcutaneously into athymic nude mice and observing their development into well-differentiated squamous cell carcinoma; (2) immunohistochemical staining using antibodies (AE1/AE3, CAM5.2 and MAK 6) which show the presence of cytokeratin intermediate filaments; and (3) electron microscopy demonstrating the morphologic features of epithelial cells with the presence of desmosomes. The cytogenetic abnormalities found in both the primary culture and SLMT-1 included der(1;14)(q10;q10), add(1)(p1?), +1, +2, del(3)(q11), +6, +7, i(8)(q10), +8, +10, +11, -13, -15, +16, +17, -18, -19, -Y and marker chromosomes. Additional changes observed in the 34th passage included gains as well as losses of both numerical and structural abnormalities. Comparative genomic hybridization (CGH) indicated copy number gains on chromosomal regions 3q32-qter, 5p, 8p12-p11.2, 11q13-q22 and 13q22-qter, and loss of the Y. The gains of 8p12-p11.2 in SLMT-1 cells are novel to ESCC. Based on its distinct and common characteristics, the SLMT-1 cell line serves as a useful tool for studying the molecular and genetic basis of the pathogenesis of ESCC.
Animals↗