ABSTRACT
Inverse kinematics (IK) of concentric tube continuum robots (CTRs) is associated with two main problems. First, the robot model (e.g., the relationship between the configuration space parameters and the robot end-effector) is not linear. Second, multiple solutions for the IK are available. This paper presents a general approach to solve the IK of CTRs in the presence of constrained environments. It is assumed that the distal tube of the CTR is inserted into a cavity while its proximal end is placed inside a tube resembling the vessel enabling the entry to the organ cavity. The robot-tissue interaction at the beginning of the organ-cavity imposed displacement and force constraints to the IK problem to secure a safe interaction between the robot and tissue. The IK in CTRs has been carried out by treating the problem as an optimization problem. To find the optimized IK of the CTR, the cost function is defined to be the minimization of input force into the body cavity and the occupied area by the robot shaft body. The optimization results show that CTRs can keep the safe force range in interaction with tissue for the specified trajectories of the distal tube. Various simulation scenarios are conducted to validate the approach. Using the IK obtained from the presented approach, the tracking accuracy is achieved as 0.01 mm which is acceptable for the application.
ABSTRACT
Background: Bone marrow hypoxia can promote leukemia progression in human cases of acute myeloid leukemia (AML). In addition, low oxygen tension is able to regulate the expression of different genes involved in malignancy. In this study, we hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF-A) genes were assessed as principal regulators of hypoxia in do novo AML patients. Methods: Peripheral blood and bone marrow samples were collected from 57 AML patients and 17 normal control subjects with informed consent. Expression of HIF1α and VEGF-A was then evaluated using quantitative real-time PCR (Q-Real time PCR) and data were analyzed with SPSS 16. Result: HIF1α and VEGF-A showed overexpression in AML patients compared to normal controls (P <0.0001 and P<0.005, respectively). The expression level of HIF1α was significantly higher in AML-M3 cases versus AML-non M3 cases. Furthermore, there was a positive correlation between HIF1α and VEGF-A ( P <0.0001 and r = 0.497). Conclusion: Adding to the many studies on the role of hypoxia in solid tumors, our data indicate that HIF1a and VEGF-A overexpression also occurs in AML patients. We consider that this is possibly involved in leukemic cell growth and therefore could be a promising target for clinical control.
Subject(s)
Biomarkers, Tumor/metabolism , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Leukemia, Myeloid, Acute/metabolism , Vascular Endothelial Growth Factor A/metabolism , Adolescent , Adult , Aged , Aged, 80 and over , Biomarkers, Tumor/genetics , Case-Control Studies , Child , Child, Preschool , Female , Follow-Up Studies , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Infant , Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/pathology , Male , Middle Aged , Prognosis , Vascular Endothelial Growth Factor A/genetics , Young AdultABSTRACT
INTRODUCTION: Relapsing-remitting multiple sclerosis is a debilitating neurological disease accompanied with adverse consequences for quality of life. The purpose of this study was to investigate the role of relapsing-remitting multiple sclerosis on psychological, disease-related, socioeconomic, and demographic determinants of health-related quality of life of patients. METHODS: In this cross-sectional descriptive study, 193 patients with relapsing-remitting multiple sclerosis were selected by compliance sampling method among the patients who attended the Iranian Multiple Sclerosis Association in Tehran from March 2014 to July 2014; and they completed the Multiple Sclerosis Quality of Life Questionnaire, the Depression Anxiety and Stress Scales, and the Socio-demographical Questionnaire. Then, a hierarchical multiple regression analysis with the stepwise method is used for data analysis by the PASW-18. RESULTS: According to the findings, in model 1, low socioeconomic status (SES) had a negative coefficient (beta=-0.30, p<0.01), and treatment history had a positive coefficient (beta=0.22, p<0.01). In model 2, while all variables of model 1 were controlled, depression had a negative coefficient (beta=-0.26, p<0.05), while disorder severity of multiple sclerosis had positive coefficients in lower level (beta=0.35, p<0.001), moderate level (beta=0.23, p<0.01), and severe level (beta=0.22, p<0.01). Other studied variables in model 1, and stress and anxiety in model 2 were not predicted in terms of the quality of life (p>0.05). CONCLUSION: Unfavorable SES, lack of effective treatment history, higher depression, and signs and symptoms severity of multiple sclerosis significantly predict decreased health-related quality of life in patients with relapsing-remitting multiple sclerosis. Thus, it is consequential to emphasize the value of tailored intervention for attending to these factors in the treatment and rehabilitation agendas for improvement of health-related quality of life in relapsing-remitting multiple sclerosis.
